production, modification, and characterization of …

PRODUCTION, MODIFICATION, AND CHARACTERIZATION OF NATURAL BAMBOO

FIBER

by

AMK BAHRUM PRANG ROCKY

AMANDA J. THOMPSON, COMMITTEE CHAIR

MARK E. BARKEY

SELVUM PILLAY

KEVIN H. SHAUGHNESSY

RYAN M. SUMMERS

A DISSERTATION

Submitted in partial fulfillment of the requirements

for the degree of interdisciplinary Doctor of Philosophy

in the Department of Metallurgical and Materials Engineering

in the graduate school of

The University of Alabama

TUSCALOOSA, ALABAMA

2019

Copyright AMK Bahrum Prang Rocky 2019

ALL RIGHTS RESERVED

ii

ABSTRACT

In an effort to extract natural bamboo fiber (NBF) from bamboo for textiles and other uses, four

bamboo species Bissetii, Giant Gray, Moso, and Red Margin were chosen for investigation.

Conventional fibers such as cotton, polyester, regular rayon, and 12 commercial bamboo viscose

were included for comparative study. By using different chemicals and routes, 144 types of

NBFs were produced. Assessments on fiber yield percentages (40-77%), average lengths (1.50-

37.10 cm), fineness (9.68—93.3 Tex), and overall qualities, determined at least 47 sets were

prospective for commercial use. Hand-spinning was executed on three sets of NBFs after

blending with cotton fibers. Investigation on moisture regain (𝑀𝑅) and moisture content (𝑀𝐶),

revealed that bamboo plants and NBFs had 𝑀𝑅 = 8.0% and 𝑀𝑅 = 7.5% which was lower than

rayon and bamboo viscose fiber (~11% and ~10%) but higher than raw cotton fibers (~5.7% and

5.4%). Among tensile properties, breaking tenacity of longer NBFs (33-37 cm) was 64-140

N/Tex and elongation at break was 2.0-2.5%; these values were 1.50-2.50 N/Tex and 8.0-11.0%

respectively for blended yarns.

Elemental, chemical, and crystallographic investigations were accomplished by energy-

dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), ATR-FTIR

(Attenuated Total Reflectance Fourier Transform Infra-Red), Raman spectroscopy (RS) and

X-ray diffraction (XRD) techniques. Bamboo plants were estimated to be 70-78% carbon (C)

and 20-30% oxygen (O) atoms, and O/C ratio of 0.26-0.33. The NBFs had a higher O/C ratio of

0.58-0.70. Comparisons of the spectra revealed the differences between bamboo-NBF and other

fibers. Some distinct lignocellulosic peaks were in NBFs that could be responsible for unique

iii

properties. The crystallinity index (CI) of bamboo plants was 63-67% but CI of NBFs was higher

69-73% with crystallite sizes of 35-39 Å (3.5-3.9 nm). Four reflection planes and other

properties are also documented.

A suitable antibacterial test method was modified for quantitative estimation of bacterial

reduction. Results suggest that though 11 out of 12 bamboo viscose products failed to exhibit

inhibition against the bacteria, most of the bamboo and NBF specimens successfully showed a

bacterial reduction of 8-95% against Klebsiella pneumoniae and 3-50% against Staphylococcus

aureus.

iv

DEDICATION

I would like to dedicate this dissertation —

To my mother who used to say “if you fail and stop, that means you are unfit on earth” and

encourage me to work hard for fulfilling my own dreams. She was my heaven and the loveliest

person in my life. I miss her every moment.

To my father who sacrificed the last penny for me and my siblings hiding his own sickness and

sufferings for years and never complained to anybody. I learned how to work hard and sacrifice

own happiness for others. He used to encourage me, “always try to do good for humanity even if

it is very insignificant to make the world safe and peaceful for all people, it will at least

encourage other people to do good things. You can never be really happy seeing your neighbors

unhappy.”

To my siblings, and family who are the source of my energy and inspiration.

To my advisor, Dr. Amanda Thompson, who has always been more than an advisor. She has

been a guardian, a guide, a patron, a well-wisher and a best teacher throughout my MS and Ph.D.

studies and research activities.

To all homeless and destitute people who make me feel how lucky I am with so many privileges

and benefits. I could be one of them. This feeling always reenergizes me in my tiredness and

failures.

To all people who think about and work for all mankind.

v

LIST OF ABBREVIATIONS AND SYMBOLS

NBF Natural bamboo fiber

w/w Weight to Weight concentration

torr A unit of pressure; 1 torr = 133.32 Pascals

CH3COOH Acetic acid

AG ACS grade

AATCC American Association of Textile Chemists and Colorists

ACS American Chemical Society

ASTM American Society for Testing and Materials

ATCC American Type Culture Collection

Å Angstrom; 1 Å = 10−10 m

AR Ash & Rose

At% Atomic percentage

ATR Attenuated total reflectance

BV Bamboo viscose

BVC Bamboo viscose and cotton blend

BVS Bamboo viscose and spandex blend

BSA Bamboosa® LLC

BB Bambu Batu

BBB Big Boy Bamboo

B or BS Bissetii bamboo

vi

BCF Bleached cotton fiber

BCF Bleached cotton fibers

BVCS Blend of bamboo viscose, cotton, and spandex

Ca Calcium

C Carbon

Cari Cariloha® Bamboo

cm Centimeter

Co Cobalt

COD Coefficient of determination

CFU Colony-forming unit

Co. Company

Ne Cotton count/Number in English system

CI Crystallinity index

Cu Cuprum, copper

dtex Decitex

°C Degree Celsius

°F Degree Fahrenheit

DSC Differential scanning calorimetry

DP Double-ply

eV Electron volt, a unit of energy; 1 eV = 1.602 177×10-19 Joules

EDS Energy-dispersive X-ray spectroscopy

E. coli Escherichia coli

et al. et alia, and others

vii

FD Faerie's Dance

FE-SEM Field Emission Scanning Electron Microscope

FTIR Fourier Transform Infra-Red spectroscopy

FF Free Fly Apparel®

FWHM Full-width half maximum

VWR George Van Waters and Nat Rogers company

G or GG Giant Gray bamboo

g Gram

Tex Gram weight per 1000 m, Tex count

GA Green Apple Active

HiVac High vacuum

h Hour

H2O2 Hydrogen peroxide

Inc. Incorporated

IR Infrared

ISO International Standards Organization

K. pneumoniae/KP Klebsiella pneumoniae

lb Libra, pound-mass

LLC Limited liability company

LR Liquor ratio

L Liter

M:L Material : liquor

μg Microgram

viii

μL Microliter

μm Micrometer

mL Milliliter

mm Millimeter

Min. Minute

𝑀𝐶 Moisture content

𝑀𝑅 Moisture regain

M or MS Moso bamboo

nm Nanometer

Na Natrium, sodium

NCC Natural Clothing Company

B-16 NBF from Bissetii bamboo through route-16






G-10 NBF from Giant Gray bamboo through route-10






ix




M-14 NBF from Moso bamboo through route-14







R-1 NBF from Red Margin bamboo through route-1













x














NY New York

N Nitrogen

NMR Nuclear magnetic resonance

No. Number

OD Optical density

O Oxygen

O/C Oxygen to carbon ratio

% C Percentage of cotton

% P Percentage of polyester

% S Percentage of spandex

xi

%R Percentage reduction

Piko Piko Clothing

pH Power/potential of hydrogen, measure of acidity or alkalinity

RS Raman spectroscopy

RCF Raw cotton fiber

RCF Raw cotton fibers

RG Reagent grade

R or RM Red Margin bamboo

RR/RT/CR Regular rayon/rayon twill/conventional rayon

RSF Relative Sensitivity Factor

RT Room temperature

SEM Scanning electron microscope

s Second

Si Silicon

SP Single-ply

NaHCO3 Sodium bicarbonate

NaOH Sodium hydroxide

Na2SiO3 Sodium silicate

Na2SO3 Sodium sulfite

Na5P3O10 Sodium triphosphate

S. aureus/SA Staphylococcus aureus

H2SO4 Sulfuric acid

TAPPI Technical Association of the Pulp and Paper Industry

xii

TG Technical grade

TM Test method

hν The energy of light

3D Three dimensional

TSA Tryptic soy agar

TSB Tryptic soy broth

UV Ultra-violet

UCF Unbleached cotton fabric

N Unit of force, Newton

USA United States of America

UCF Untreated cotton fabrics

H2O Water

λ Wavelength

Wt% Weight percentage

WAXD Wide-angle X-ray diffraction

XRD X-ray diffraction

XPS X-ray photoelectron spectroscopy

Yala Yala Designs

Zn(NO3)2 Zinc nitrate

xiii

ACKNOWLEDGMENTS

Though this dissertation is designated to my name as the author, this was far more than a sole

endeavor. My biggest thank and credit goes to my advisor Dr. Amanda J. Thompson. Thank you

for instructions, guides, supports, ideas, and collaborations all the times, training me and keeping

me on track throughout my dissertation. I would like to acknowledge financial (graduate council

fellowships and scholarships) and all other supports and facilities provided by the graduate

school, The University of Alabama (UA). I would also like to acknowledge financial support, lab

facilities, and different academic assistance from the Department of Clothing, Textiles and

Interior Design (CTID) in College of Human Environmental Science and Department of

Metallurgical and Materials Engineering (MTE) in College of Engineering, The University of

Alabama. I thank all of the faculty and officials of the departments.

I am thankful to Dr. Gregory B. Thompson (Professor, Departmental Graduate Program

Director, MTE, UA) for your supports in funding and lab facilities. Thank you for providing

training and expenses for X-ray diffraction (XRD), scanning electron microscopes (SEM) and

energy-dispersive spectroscopy (EDS) in FEI Quanta, EDAX, JEOL 7000F, Apreo S and X-ray

photoelectron spectroscopy experiments. Your instructions and advice in crystallography helped

me a lot in my dissertation.

I am grateful to each of the member in my dissertation committee. Thank you, Dr. Mark

E. Barkey (Professor, Interim Department Head of Aerospace Engineering and Mechanics, UA)

for instruction in finite element analysis and theory of elasticity courses, training, guiding and

providing me lab facilities with tensile tests. Thank Dr. Kevin H Shaughnessy (Professor,

xiv

Department of Chemistry and Biochemistry, UA) for your instructions in organic chemistry and

guiding me in chemical characterization, processing, and tests. Thanks for your advice,

discussions, ideas and connecting me with different labs and experts. I am pleased to Dr. Selvum

Pillay (Chair and Professor, Department of Materials Science and Engineering, School of

Engineering, The University of Alabama at Birmingham, UAB) for serving in the committee and

for your advice and suggestions. I would like to thank Dr. Ryan Summers (Assistant Professor

Department of Chemical and Biological Engineering, UA) for your instructions in bioprocessing

engineering, discussions, guides and advice about working with bacteria and the antibacterial

tests.

I would like to express my gratitude to Ms. Patricia McCaffrey (MBY Lab Supervisor)

and Elizabeth Kitchens (Culture Curator) in the Department of Biological Sciences, UA for their

supports, guides, instructions, and advice for antibacterial tests.

My special thanks go to Mr. Rob Holler (Instrumentation Specialist, Central Analytical

Facility, CAF, UA) for training, instructions, assistances with XPS, XRD, EDS, and SEM

instruments. I will never forget your cordiality in teaching me all the instruments and working

with their data. I would also like to thank Mr. Johnny Goodwin (Instrumentation Specialist,

CAF, UA) and Mr. Richard Martens (Manager, CAF, UA) for their supports and assistances with

SEM instruments.

I am thankful to Dr. Kenneth Belmore (Nuclear Magnetic Resonance Facility Manager,

Department of Chemistry and Biochemistry, UA) for your advice, instructions, and training with

FTIR. I would also like to express my gratefulness to Dr. Jair Lizarazo-Adarme (Research

Engineer, Adjunct Faculty, Department of Chemical and Biological Engineering, UA) for

training me with Raman spectroscopy and Freeze dryer and giving me access to the labs. My

xv

special thanks go to Catherine Scott, hand spinner and fiber artist, for her support in the spinning

of bamboo and cotton fiber blends. I would like to thank all the faculty, fellow students, friends,

family and everyone for guiding and encouraging me throughout the course of my dissertation.

xvi

CONTENTS

ABSTRACT .................................................................................................................................... ii

DEDICATION ............................................................................................................................... iv

LIST OF ABBREVIATIONS AND SYMBOLS ........................................................................... v

ACKNOWLEDGMENTS ........................................................................................................... xiii

LIST OF TABLES ........................................................................................................................ xx

LIST OF FIGURES .................................................................................................................... xxii

CHAPTER 1. INTRODUCTION ............................................................................................. 1

1.1 Production of Natural Bamboo Fibers ............................................................................. 4

1.2 Characterization of Different Properties of Bamboo and NBF ........................................ 6

1.3 Antibacterial Investigation and Comparison .................................................................. 10

CHAPTER 2. PRODUCTION AND MODIFICATION OF NATURAL BAMBOO FIBERS

FROM FOUR BAMBOO SPECIES, AND THEIR PROSPECTS IN TEXTILE

MANUFACTURING ................................................................................................................... 12

2.1 Abstract .......................................................................................................................... 12

2.2 Introduction .................................................................................................................... 13

2.3 Methodology .................................................................................................................. 16

2.3.1 Materials ................................................................................................................. 16

2.3.2 Apparatus ................................................................................................................ 17

2.3.3 Initial Treatments .................................................................................................... 17

2.3.4 Delignification ........................................................................................................ 18

2.3.5 Modification ............................................................................................................ 20

2.3.6 Final Treatments ..................................................................................................... 22

xvii

2.3.7 Spinning .................................................................................................................. 22

2.3.8 Tests and Assessments ............................................................................................ 22

2.4 Results and Discussions ................................................................................................. 25

2.4.1 Discussions on Natural Bamboo Fibers Extraction ................................................ 25

2.5 Moisture Regain and Content ......................................................................................... 27

2.6 Incineration Behavior (Burning Test) ............................................................................ 28

2.7 The Solubility of Bamboo and NBF .............................................................................. 29

2.8 Microscopic Analyses .................................................................................................... 30

2.8.1 The diameter of the Single Natural Bamboo Fibers ............................................... 30

2.8.2 Morphology............................................................................................................. 30

2.9 Fiber Length and Yield Percentage ................................................................................ 32

2.10 Fiber Fineness ............................................................................................................. 35

2.11 Tensile Properties ....................................................................................................... 36

2.12 Conclusions ................................................................................................................ 37

2.13 References .................................................................................................................. 38

CHAPTER 3. CHARACTERIZATION OF THE CRYSTALLOGRAPHIC PROPERTIES

OF BAMBOO PLANTS, NATURAL AND VISCOSE FIBERS BY X-RAY DIFFRACTION

METHOD 44

3.1 Abstract .......................................................................................................................... 44

3.2 Introduction .................................................................................................................... 45

3.3 Methodology .................................................................................................................. 47

3.3.1 Materials and machines........................................................................................... 47

3.3.2 Extraction of Natural Bamboo Fibers (NBFs) ........................................................ 47

3.3.3 Crystallographic Analyses by XRD ........................................................................ 49

3.4 Results and Discussion ................................................................................................... 53

3.5 Crystallographic Analyses.............................................................................................. 53

xviii

3.5.1 Crystallinity Indexes (CIs), Diffraction Angles, and Lattice Planes ...................... 53

3.5.2 Crystallite Dimensions and Interplanar Spacings ................................................... 60

3.6 Conclusions .................................................................................................................... 60

3.7 References ...................................................................................................................... 61

CHAPTER 4. ANALYSES OF THE CHEMICAL COMPOSITIONS AND STRUCTURES

OF FOUR BAMBOO SPECIES AND THEIR NATURAL FIBERS BY INFRARED, LASER

AND X-RAY SPECTROSCOPIES .............................................................................................. 66

Abstract ..................................................................................................................................... 66

4.1 Introduction .................................................................................................................... 67

4.2 Methodology .................................................................................................................. 70

4.2.1 Materials and machines........................................................................................... 70

4.2.2 Extraction of Natural Bamboo Fibers (NBFs) ........................................................ 71

4.2.3 Elemental analyses by XPS & EDS ........................................................................ 71

4.2.4 FTIR and Raman: Analyses of Chemical Groups................................................... 72

4.3 Results and Discussion ................................................................................................... 73

4.3.1 Elemental analyses .................................................................................................. 73

4.3.2 X-ray Photoelectron Spectroscopy (XPS) .............................................................. 75

4.4 FTIR and Raman: Identifying Chemical Groups ........................................................... 80

4.5 Conclusions .................................................................................................................... 91

4.6 References ...................................................................................................................... 92

CHAPTER 5. INVESTIGATION AND COMPARISON OF ANTIBACTERIAL

PROPERTY OF BAMBOO PLANTS, NATURAL BAMBOO FIBERS AND COMMERCIAL

BAMBOO VISCOSE TEXTILES ................................................................................................ 97

5.1 Abstract .......................................................................................................................... 97

5.2 Introduction .................................................................................................................... 98

5.2.1 Methods for Antibacterial Activity Assessment ................................................... 100

5.3 Methodology ................................................................................................................ 103

xix

5.3.1 Materials ............................................................................................................... 103

5.3.2 Equipment ............................................................................................................. 104

5.3.3 Extractions of Natural Bamboo Fibers ................................................................. 104

5.3.4 Sample Preparation for antibacterial tests............................................................. 106

5.3.5 Antibacterial Tests and Assessments .................................................................... 106

5.4 Results and Discussions ............................................................................................... 109

5.4.1 Assessment by Spectrophotometric technique...................................................... 109

5.4.2 Assessment by Viable Plate Counting Technique ................................................ 110

5.4.3 Antibacterial Property of Bamboo, NBF and Bamboo Viscose ........................... 113

5.5 Conclusions .................................................................................................................. 118

5.6 References .................................................................................................................... 119

CHAPTER 6. CONCLUSIONS ........................................................................................... 125

REFERENCES ........................................................................................................................... 129

xx

LIST OF TABLES

Table 1. Properties of the natural bamboo fibers from different studies ........................................ 7

Table 2. List of all recipes used in different processes of natural bamboo fiber (NBF)

extraction........................................................................................................................... 18

Table 3. Processing routes of the selected natural bamboo fiber (NBF) samples for different tests

and use of NaOH in each route ......................................................................................... 21

Table 4. Moisture/water content (%) of culms from four fresh bamboo plants ........................... 25

Table 5. Burning tests and observations of different conventional fibers, raw bamboo, and natural

bamboo fiber (NBF) samples ............................................................................................ 28

Table 6. Solubility test of different conventional fibers, raw bamboo and natural bamboo fiber

(NBF) samples in sulfuric acid ......................................................................................... 29

Table 7. Lengths and yield percentages of natural bamboo fibers (NBFs) of four bamboo species

extracted through different techniques and routes ............................................................ 33

Table 8. The fineness of the natural bamboo fibers (NBFs) extracted from four bamboo plants 35

Table 9. Breaking tenacity and elongation of natural bamboo fibers and cotton-blended

yarns… ............................................................................................................................. .36

Table 10. Estimated crystallinity indexes (CIs) of different bamboo species, NBFs, bamboo

viscose products, and conventional fibers by using Segal and Deconvolution methods on

X-ray diffraction data ........................................................................................................ 54

Table 11. Size of the crystallites, reflection planes, diffraction angles, and interplanar distances

of four bamboo species and natural bamboo fibers (NBFs) from X-ray (Co Kα source)

diffraction technique ......................................................................................................... 56

Table 12. Recipes, chemicals and processing conditions for NBF extraction .............................. 71

Table 13. Elemental compositions and oxygen-carbon ratios of different bamboo species and

their fibers ......................................................................................................................... 73

Table 14. Concentration, O/C ratios and binding energies of different elements in four bamboo

specimens from XPS investigation ................................................................................... 75

Table 15. Binding energies, atomic percentages of Carbon and Oxygen with their components in

XPS analysis of different bamboo species ........................................................................ 80

xxi

Table 16. Chemical bonds and band characteristics of ATR-FTIR and Raman spectra of four

bamboo species, natural bamboo fibers (NBFs), bamboo viscose, regular rayon, and

cotton fibers ...................................................................................................................... 87

Table 17. Names and compositions of different commercial textile products and relevant

information ...................................................................................................................... 103

Table 18. Different chemicals and conditions applied to different stages of natural bamboo fiber

(NBF) extraction ............................................................................................................. 105

Table 19. Percentage reduction of the optical density (OD) of different sample inoculated

bacterial solutions after incubation of 24 h at 37°C ........................................................ 109

Table 20. Percentage reduction of bacteria by different commercial textile products ............... 113

Table 21. Percentage reduction of bacteria by four bamboo species and their natural fibers .... 115

xxii

LIST OF FIGURES

Figure 1. a general flowchart of natural bamboo fiber (NBF)extraction from four bamboo species

using varying conditions. ...................................................................................................... 19

Figure 2. Photographs of the natural bamboo fibers (NBFs) from four bamboo plants and hand-

carded yarn blended with cotton fiber. ................................................................................. 26

Figure 3. Comparison of moisture regain (%) and moisture content (%) of conventional fibers,

bamboo, and natural fibers. ................................................................................................... 27

Figure 4. The diameter of the single natural bamboo fibers from four bamboo plants. ............... 30

Figure 5. SEM images of four raw bamboo strips and natural bamboo fibers (NBFs) taken by

JEOL 7000 (a—d, h) and Apreo S (e—g, i). ........................................................................ 31

Figure 6. The relationship among fiber lengths, yield percentages and total use of NaOH in

natural bamboo fiber (NBF) extraction. ................................................................................ 34

Figure 7: Bamboo sliced strips prepared for X-ray diffractometry in Bruker AXS. .................... 49

Figure 8. Deconvolution method applied to the X-ray (from Cobalt source, Co K) diffraction

pattern of natural bamboo fiber (NBF) M-25 from Moso bamboo sample by using FitPeak

processing. ............................................................................................................................ 51

Figure 9. X-ray diffraction patterns of four bamboo species showing different peaks for

determining the crystallinity indexes and the crystal sizes. .................................................. 55

Figure 10. Comparison of X-ray (from Co K source) diffraction patterns among four bamboo

species, natural bamboo fibers (NBFs) and cotton. .............................................................. 58

Figure 11. Change in crystallinity indexes as natural bamboo fibers (NBFs) were extracted into

finer forms or count (Ne) through different stages of processing. ........................................ 59

Figure 12. X-ray photoelectron spectroscopic survey spectra of four bamboo species ............... 77

Figure 13. Deconvoluted peaks of the components (C1-C4) of C 1s peak from XPS spectra of 4

bamboo plants: (a) Bissetii, (b) Giant Gray, (c) Moso, and (d) Red Margin bamboo. ......... 78

Figure 14. Deconvoluted peaks of the components (O1 and O2) of O 1s peak from XPS spectra of

4 bamboo plants: (a) Bissetii, (b) Giant Gray, (c) Moso, and (d) Red Margin bamboo. ...... 79

Figure 15. Comparisons of ATR-FTIR and Raman spectra of raw bamboo samples and natural

bamboo fibers (NBFs)........................................................................................................... 81

xxiii

Figure 16. Comparisons of Raman spectra of four bamboo species, natural bamboo fiber (NBF)

and cotton fiber. .................................................................................................................... 82

Figure 17. Comparisons of Raman spectra of Red Margin bamboo, natural bamboo fibers

(NBFs) from four species and bamboo viscose fiber............................................................ 83

Figure 18. Different peaks and their positions in the ATR-FTIR spectrum of Red Margin

bamboo specimen.................................................................................................................. 84

Figure 19. Different peaks and their positions in the Raman spectrum of Red Margin bamboo

specimen. .............................................................................................................................. 85

Figure 20. Unexpected bacterial growth on TSA plates inoculated with raw Bissetii bamboo

(BS) and raw cotton fibers (RCF) when samples were non-sterilized and exposed to the

environment vs. bacterial growth by sterilized samples. .................................................... 111

Figure 21. Sizes of the bacterial colony of S. aureus inoculated with natural bamboo fibers

(NBFs) after 24 h vs 60 h with almost unchanged counts. ................................................. 112

Figure 22. Growth of the bacterial colony on TSA plates inoculated with different samples. .. 114

Figure 23. Growth of bacterial colony on TSA plates inoculated with different natural bamboo

fiber (NBF) samples. ........................................................................................................... 116

Figure 24. Microscopic (SEM) images of natural bamboo fibers (NBFs) from four different

species showing non-fibrous contents responsible for natural properties. ......................... 117

1

CHAPTER 1. INTRODUCTION

Increased demand for eco-friendly and sustainable textiles and clothing is driving textile scholars

to investigate the fiber production and modification from fast-growing bamboo plants. In recent

years, many scholarly works have been published on natural bamboo fiber production and

characterization. The research on this topic is becoming very popular in modern eco-friendly

textile production. Though production of natural bamboo fiber and its application in textile and

clothing is very promising, the lack of successful research on extracting suitable natural bamboo

fiber (NBF) for textiles has inhibited the promotion of its use in industrial textiles production.

Recently, with the advantage of faster growth and a larger cellulosic biomass, bamboo has been

widely used in pulp production for paper and regenerated celluloses (Batalha et al., 2011;

ChaoJun, ShuFang, ChuanShan, & DaiQi, 2014; Correia, Santos, Mármol, Curvelo, &

Savastano, 2014; He, Cui, & Wang, 2008; Junior, Teixeira, & Tonoli, 2018; Ma, Huang, Cao,

Chen, & Chen, 2011; Sugesty, Kardiansyah, & Hardiani, 2015; Xie et al., 2015). Although

bamboo viscose, a regenerated cellulosic fiber that can begin as a pulp product, is being

produced and is commercialized globally, natural bamboo fiber is not as common because of the

complexity of processing and costs. Since bamboo is a native plant in Asia and grows

abundantly, most of the bamboo viscose fiber production facilities are in China. There are very

few companies interested in producing natural bamboo fibers and it is also unclear the numbers

and identities of such companies, if any, of the natural bamboo textiles are in the market

(Steffen, Marin, & Müggler, 2013).

2

Research has begun in recent years on natural bamboo fiber extraction. The interest of

producing natural bamboo fibers comes from its properties which are not common in traditional

textile fibers as a cluster along with the bamboo plant’s green status. The claimed features

include soft hand and comfort, durability, breathability, antibacterial properties, moisture

absorbency, protection against ultraviolet rays, better heat management (heat retention), anti-

itching, antistatic, hypoallergenic, anti-odorous, and ease of dyeability (Afrin, Kanwar, Wang, &

Tsuzuki, 2014; Afrin, Tsuzuki, & Wang, 2009; Bambrotex, 2007; Rocky, 2017; Tanaka et al.,

2014; Zupin & Dimitrovski, 2010). Although these properties are theoretically described, there is

not enough scientific research to support all the claims for all the properties (Hardin, Wilson,

Dhandapani, & Dhende, 2009; McLarren, 2010; Michael, 2008). Moreover, these properties are

also not confirmed by standardization authorities on currently available commercial bamboo

clothing (regenerated bamboo fiber). If the properties are present, some of the features may be

artificially introduced to the viscose fibers by chemical means. While the manufacturers and

sellers are taking advantage of this confusion by making unproven claims about the properties of

their products, most of the research has failed to prove all of these properties as inherently part of

commercial viscose products (Hardin et al., 2009; Nayak & Mishra, 2016; Xi, Qin, An, & Wang,

2013). This incongruity is further stretched when compared to the production processes. An in-

depth study suggests that the currently available literature fails to introduce a successful

methodology that could be applied in the commercial or large-scale production of natural

bamboo fibers. However, the conventional chemical-dependent viscose process is already widely

applied for regenerated bamboo viscose production which is an ecologically hazardous process

and may fail to retain natural properties of bamboo fibers (Nayak & Mishra, 2016). There is no

official classification of bamboo textiles according to the US federal trade commission. Retailers

3

have claimed viscose projects as bamboo clothing and have suffered penalties (13-cv-00002-

TFH, 2013; 15-cv-02130-APM, 2015; FTC, 2010b, 2010a; Hardin et al., 2009; McLarren, 2010).

So it is very crucial to design an effective production process of natural bamboo fibers.

Moreover, investigation and examination of the properties of the fiber will bolster the

understanding of natural bamboo fibers. Thus, research to establish suitable methods of natural

bamboo fiber production and characterizing different properties of that fiber is very timely in the

textile sector.

Since bamboo is a fast-growing plant which is capable of producing a high amount of

lignocellulosic biomass, it has been studied for utilization for multiple purposes. As a

consequence, the viscose process for the production of regenerated cellulosic fibers has taken

advantage of the cellulose content of the bamboo plant. This process was previously applied to

cotton linter and wood pulp (Fu, Li, et al., 2012). In the past few years, scholarly circles have

begun investigating bamboo for naturally produced fiber as opposed to viscose fibers. The main

reasons are- the viscose process requires a huge amount of water, energy and toxic chemicals,

and removes the distinctive properties of bamboo fibers. Since most of the existing textile

processes have a significant impact on environmental pollution and may prove unsustainable for

profitability, researchers and manufacturers are interested in focusing on sustainable production

processes and raw materials to develop the next materials for textiles (Abdul Khalil et al., 2012;

Afrin et al., 2014; Parisi, Fatarella, Spinelli, Pogni, & Basosi, 2015; Rocky, 2017; Steffen et al.,

2013; Waite, 2009). Bamboo provides the possibility to produce eco-friendly and sustainable

textiles products if processed through non-hazardous techniques. Reasonably, a myriad of efforts

has been employed to produce natural bamboo fibers for textiles, clothing, composites and other

products.

4

1.1 Production of Natural Bamboo Fibers

Though the research-interest in natural bamboo fibers is growing, the difficulties of fiber

separation due to strongly bonded lignin has been discouraging. As a result, most researchers

have discontinued their studies on the endeavor. The biggest challenge to NBF production is

delignification which is defined as the process of separating fibers from lignin and other binding

components in bast materials. The amount of lignin and other undesired components in fibers are

different for different bamboo species (Muhammad, Rahman, Hamdan, & Sanaullah, 2019;

Nayak & Mishra, 2016). Almost 1200-1500 bamboo species under 70-91 genera are documented

worldwide (Abdul Khalil et al., 2012; Chaowana, 2013; Correia et al., 2014; Hardin et al., 2009;

Kweon, Hwang, & Sung, 2001; Morton, 2005; Rai, Ghosh, Pal, & Dey, 2011; Rocky, 2017;

Zakikhani, Zahari, Sultan, & Majid, 2014a). However, only around 50 species have been studied

for bamboo natural and viscose fibers production. For the natural bamboo fiber production

studies, some identical initial steps to viscose production such as cutting bamboo culms in-

between nodes, splitting, retting or crushing or braising were employed followed by different

processes.

The enzymatic and the microbial or bacterial processes are considered the eco-friendliest

processes for natural fiber production. However, these processes are extremely slow and not

effective for bamboo fiber extraction for textiles. Moreover, the cost of the equipment,

microbes/bacteria and enzymes are very high, which would not be commercially competitive.

None of the current enzymatic/microbial process research clearly mentioned successful results

on producing bamboo fibers followed by spinning or weaving for textiles (Afrin et al., 2014; Fu,

Li, et al., 2012; Fu, Zhang, Yu, Guebitz, & Cavaco-Paulo, 2012; Hanana et al., 2015; Liu,

Cheng, Huang, & Yu, 2012; Rocky, 2017). Therefore, investigation on extracting the natural

5

bamboo fibers by solely using the enzymatic or bacterial treatment is not a productive idea for

textile production. Enzymes or bacteria are found to be very effective when applied after the

initial extraction of fibers in bundle form. One such study mentioned spinning of 100% natural

bamboo yarn and blended yarn (Steffen et al., 2013). However, successive research or

commercial implementation was not reported perhaps due to the expense of the process.

Some of the mechanical investigations were carried out by applying a steam explosion at

an elevated temperature and pressure, while others were executed at high-temperature boiling.

Although the process is eco-friendlier than the chemical process, except for the use of higher

heat energy, it was reported as unable to separate fibers completely (Biswas, Shahinur, Hasan, &

Ahsan, 2015; Kim, Okubo, Fujii, & Takemura, 2013; Ogawa, Hirogaki, Aoyama, & Imamura,

2008; Okubo, Fujii, & Yamamoto, 2004; Phong, Fujii, Chuong, & Okubo, 2012; Rao & Rao,

2007; Trujillo et al., 2014; Witayakran, Haruthaithanasan, Agthong, & Thinnapatanukul, 2013;

Zakikhani, Zahari, Sultan, & Majid, 2014b; Zakikhani et al., 2014a). Studies, where mechanical

and chemical processes were combined, were focused on fiber production for purposes other

than the textile application. The produced fibers were in bundle forms rather than in individual

form, which was not applicable for spinning purposes. Therefore, no spinning and subsequent

textile production were reported.

The chemical extraction of natural bamboo fibers was reported far more successful than

other processes (Deshpande, Rao, & Rao, 2000; Kim et al., 2013; Phong et al., 2012; Prasad &

Rao, 2011; Rao & Rao, 2007; Rocky, 2017; Zakikhani et al., 2014b). However, most of the

studies involved using a high concentration of alkali, acids or other non-ecofriendly chemicals

which is better than the viscose process but not highly eco-friendly (Liu et al., 2012; Liu, Wang,

Cheng, Qian, & Yu, 2011). Additionally, the excessive use of chemicals can destroy the natural

6

unique properties of bamboo fibers. It is possible to reduce the amount of chemicals if different

mechanical processes are applied before delignification by chemicals (Rocky, 2017).

A review of the biological or enzymatic, the mechanical or steam explosion, the chemical

and the retting processes suggests that a one-way approach would not be successful. However,

approachable guidelines could be deduced from the findings of different investigations and pilot

experiments that the combinations of mechanical, enzymatic or microbial and chemical

processes would be more effective and successful (Liu et al., 2012; Phong et al., 2012; Rocky,

2017; Steffen et al., 2013; Zakikhani et al., 2014a, 2014b). So, different combined approaches

were mainly projected in this study. Based on the information in the articles of the past research,

the most effective and available items were inspected such as different chemicals, raw materials,

machines, equipment and technologies of NBFs extraction.

1.2 Characterization of Different Properties of Bamboo and NBF

The structural, physical, chemical and mechanical properties of natural bamboo fibers produced

through different techniques have been reported in several investigations (Table 1).

Unfortunately, no standard has been formed due to the extreme incongruity of the results.

Different properties of natural bamboo fibers were reported with a wide range of values. Since

no standard method for natural bamboo fiber processing has been established, fibers produced in

different studies were different in length and diameter. In most of the cases, the properties were

determined by testing the fiber bundles rather than the individual fibers. However, some of the

properties are independent of the form (individual or bundle form) if the fibers are extracted with

natural constituents intact. It should be noted the standardized value of the different properties of

viscose (from bamboo) have already been established.

7

Table 1

Properties of the natural bamboo fibers from different studies

Property and unit value Reference

Average length (mm) 2-270 (Afrin et al., 2014; Liu et al., 2011; Rocky, 2017;

Steffen et al., 2013; Zakikhani et al., 2014b)

Average diameter (µm) of

single fiber 4-20

(Afrin et al., 2014; Komuraiah, Kumar, & Prasad,

2014; Rocky, 2017; Steffen et al., 2013)

Linear density (dtex) 2-35 (Liu et al., 2011; Rocky, 2017; Steffen et al., 2013;

Yueping et al., 2010)

Specific density (g/cm3) 0.6-1.4 (Jain, Kumar, & Jindal, 1992; Prasad & Rao, 2011;

Zakikhani et al., 2014b)

Moisture regain (%) Not available -

Water absorbance (%) Not available -

UV absorbance (%) 55.7 (UVA), 24.3 (UVB) (Afrin et al., 2014)

Crystallinity (%) 52~89 (Afrin et al., 2014; He et al., 2008; Yueping et al.,

2010)

Diffraction peaks at

angle (degree) 15-16 and 22

(He et al., 2008; Jiang, Miao, Yu, & Zhang, 2016;

Yueping et al., 2010) Diffraction plane (101), (101̅), (002)

Interplanar distance (nm) -, 5.683, 4.003

Crystal Size (Å) 35.5 (Afrin et al., 2014)

Tenacity (cN/tex) 8-35 (Liu et al., 2011; Steffen et al., 2013; Waite, 2010)

Breaking elongation (%) 1.4-2.9 (Liu et al., 2011; Prasad & Rao, 2011; Steffen et al.,

2013)

Tensile strength (MPa) 440-600 (Prasad & Rao, 2011)

Tensile Modulus (MPa) 35-46 (Prasad & Rao, 2011)

Chemical bonding

Aryl, conjugated and non-

conjugated carbonyl,

hydroxyl, hydrocarbon

(Afrin et al., 2014; Yueping et al., 2010)

The surface morphology of the natural bamboo fibers has been studied in many

investigations (Afrin et al., 2014; Cho, Kim, & Kim, 2013; He et al., 2008; Ogawa et al., 2008;

Phong et al., 2012; Shih, 2007; Tokoro et al., 2008; Y. L. Yu, Huang, & Yu, 2014; Y. Yu, Wang,

& Lu, 2014; Yueping et al., 2010; Zakikhani et al., 2014b; Zou, Jin, Lu, & Li, 2009). The surface

of the fibers has been reported as very smooth. Lignin or other components are sometimes shown

on the surface which are capable of reflecting a higher fraction of incident light. As a result, the

8

fibers look lustrous and can exhibit higher dyeing yield (darker color-shade) at a lower

concentration than that of other fibers. The cross-section of the natural bamboo fibers is circular-

shaped consisting of different layers. From the center to the outermost surface are lumen,

secondary walls, middle lamella, and primary cell walls.

The structural and the chemical composition of natural bamboo fibers are important

factors needed to understand the behavior of the fibers under different conditions. The major

components have been determined as cellulose, hemicellulose, lignin, pectin and other organic

and/or inorganic soluble and insoluble components. Different chemical groups have also been

analyzed by x-ray spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR).

Some of the identified chemical groups associated with the natural bamboo fibers are listed in

Table 1 under Chemical Bonding.

The physical and the crystallographic properties have also been investigated for natural

bamboo fibers of 2-3 bamboo species only, which is not sufficient to establish a standard. So,

further study on different species (as selected in this study) will help standardization. A wide

Gaussian range of the length of 2-270 mm and the diameter of 4-20 µm (Table 1) have been

reported. The linear density (2-35 dtex*) of the fibers have not been determined with fair

accuracy as the fiber-bundles were investigated rather than individual fibers. The specific density

(0.6-1.4 g/cm3) of the fibers has been established independent of the form (single or bundle).

However, the extraction process and the type of species influence the specific density. The

moisture regain or the moisture content percentage in standard atmospheric conditions and the

absorbance of water have not been found to be determined of standardized. The crystallinity,

* Tex is a unit of linear density of fiber or yarn used in textile industries which is the weight of the fiber/yarn in

grams per 1000 m length: 1 𝑡𝑒𝑥 =𝑔𝑟𝑎𝑚𝑠

1000𝑚 and 1 𝑑𝑡𝑒𝑥 =

1

10𝑡𝑒𝑥.

9

size of the crystallites, diffraction planes and the interplanar distances that have been studied so

far are listed in Table 1.

Different mechanical properties such as breaking strength or tenacity, breaking

elongation, tensile strength and tensile modulus have been investigated (Table 1). Since the

natural bamboo fibers were not extracted in individual form, the bundle of fibers was used for

the tests in most of the studies. Thus, the tabulated values (Table 1) might not represent

standardized values for the natural bamboo fibers.

In this study, different structural or morphological properties such as surface contour,

cross-section, average diameter, average length, and other relevant analyses were selected to be

executed by microbalance, scanning electron microscope (SEM), and optical microscopy. Since

most of the previous studies were limited to measuring the length and the diameter of the fiber

bundle, this study was focused on single/individual fiber from four bamboo species for those

measurements. Thus, this study is expected to provide a better understanding of individual

natural bamboo fibers.

Apart from surface morphology and dimensions, a crystallographic study is very

important to understand mechanical properties, coloration behavior and luster of the natural

bamboo fibers. In some studies, the modern x-ray diffractometric (XRD) technique was

employed to determine the degree of amorphousness or crystallinity, and crystal size. So, a

systematic investigation with XRD would establish crystallographic properties of the natural

bamboo fibers. Moreover, incineration behavior, moisture Regain (%) and solubility are

important properties of textiles. So, the standard AATCC (The American Association of Textile

Chemists and Colorists) /ASTM (The American Society for Testing and Materials) test methods

were chosen to measure these properties.

10

The information about the chemical/elemental composition of bamboo and its NBFs

would provide knowledge to scientifically interpret the reasons for the fibers showing unique

properties. The presence of different chemical components or chemical bonding were studied by

X-ray Spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR) (Afrin et al.,

2014; Fuentes et al., 2011; Shih, 2007; Tran, Nguyen, Thuc, & Dang, 2013). So, further studies

on the chemical composition of selected bamboo species would enrich the data and accuracy.

1.3 Antibacterial Investigation and Comparison

One of the biggest controversies about bamboo fiber/textile is the antibacterial activity. This

debate is further muddied by manufacturers and retailers claiming/labeling viscose products as

natural bamboo fibers (Hardin et al., 2009; McLarren, 2010; Rocky, 2017). While several

investigations found traces of antibacterial activity in the bamboo plant or fibers (Afrin et al.,

2014; Afrin, Tsuzuki, Kanwar, & Wang, 2012; Rocky, 2017; Singh et al., 2010; Tanaka, Kim,

Oda, Shimizu, & Kondo, 2011; Tanaka, Shimizu, & Kondo, 2013; Zheng, Song, Wang, & Wang,

2014), others did not (Hardin et al., 2009; Rocky, 2017; Xi et al., 2013). The trends in the

modern markets of textiles and clothing demand the necessity of antibacterial/antimicrobial

activity. Hence, a detailed study on antibacterial activity of the plants, natural bamboo fibers and

comparisons with the bamboo viscose commercial fabrics/products (12 brands), cotton fibers and

fabrics, and other mainstream fibers would help to resolve the debate.

According to the proposal, this study was based on four main focuses relating to NBF in

textiles. In part-1, production and modification of natural bamboo fibers (NBFs) from four

widely-grown bamboo species was expected to be conducted. Through in-depth investigation, it

was projected some accomplishments such as appropriate chemicals and ingredients for

delignification, a series of experiments to design specific routes with a proper sequence that will

11

be able to extract expected NBFs, identifying morphological, physical, and mechanical

properties, financial viability through yield percentages, production costs and other factors. In

part-2 and 3, a detailed investigation on different elemental compositions, chemical bonds and

behaviors, and crystallographic properties was anticipated to characterize bamboo plants and

NBFs along with different conventional and commercial fibers such as bamboo viscose, rayon,

cotton, and polyester. For characterization, modern instruments and techniques were chosen by

using X-ray photoelectron spectroscopy (XPS), Fourier Transform Infra-Red (FTIR)

spectroscopy with Attenuated Total Reflectance (ATR), Raman spectroscopy (RS), and X-ray

diffraction (XRD). In part-4, comprehensive trials and experiments were expected to modify a

suitable method for the antibacterial test of textile materials in any form. Since the current

standard methods are not suitable for all kinds of textile materials, this would help to solve

difficulties related to antibacterial tests of fibers, yarns, fabrics, powders, and materials with

other forms. Another major target of part 4 was to investigate and compare the antibacterial

property of bamboo plants, NBFs, 12 commercial bamboo viscose, and some other conventional

fibers.

This study was mainly focused on natural bamboo fiber extraction in the purpose of using

the fibers in textile production. Thus, all of the investigation, modification, and characterization

were executed to advance the fiber for textiles and comparing results with traditional fibers.

Correspondingly, results were reported and compared that are significant in textile sector.

12

CHAPTER 2. PRODUCTION AND MODIFICATION OF NATURAL BAMBOO

FIBERS FROM FOUR BAMBOO SPECIES, AND THEIR PROSPECTS IN TEXTILE

MANUFACTURING

2.1 Abstract

Four widely grown bamboo species, Bissetii, Giant Gray, Moso, and Red Margin, were studied

for natural bamboo fiber (NBF) extraction using 36 routes with respective fiber yield percentages

where total use of NaOH was less than 24 g/L in any specific processing route. The Red Margin

species was found to have the most potential for NBF extraction. This study provides reports on

moisture regain (average 8.0%) and moisture content (average 7.5%), incineration behavior,

solubility properties, surface morphology, length and diameter of single NBF (10—13 μm), and

fineness of NBFs from four plants and comparative results with conventional fibers. The

spinning of yarns of NBFs blended with cotton and their tensile properties were tested. NBFs

that were longer and coarser in initial stages, with high breaking tenacity of 63.74—138.63

N/Tex and lower elongation of 2.06-2.46% were judged to be good for some textile applications.

Finer and shorter NBFs provide a lower strength to the blended yarns than cotton fibers.

KEYWORDS: Natural Bamboo fibers; Natural fiber extraction; Properties of NBF; Eco-friendly

fibers; Solubility; Incineration behavior; NBF morphology.

13

2.2 Introduction

Due to its growth, sustainability, eco-friendliness, and many other advantages, bamboo has been

studied with the purpose of extracting fibers for apparel manufacturing (Nayak & Mishra, 2016;

Phong, Fujii, Chuong, & Okubo, 2012; Rocky & Thompson, 2018a, 2018c; Waite, 2010) and as

a reinforcing material in composites (Chaowana, 2013; Hebel et al., 2014; Hu & Yu, 2014; K.

Liu, Takagi, Osugi, & Yang, 2012; W. Liu, Xie, Qiu, & Fan, 2015; Phong et al., 2012; Yu,

Wang, & Lu, 2014). Though bamboo viscose is commercially available, there are numerous

efforts to extract the natural fibers from bamboo to maintain natural properties and for

environmental concerns (Nayak & Mishra, 2016). Some studies have been conducted by

applying different techniques such as enzymatic, microbial, chemical and mechanical, for natural

bamboo fiber (NBF) extraction to retain the properties of bamboo. Delignification or

degumming, a process of removing lignin and non-fibrous materials, if done by enzymes or

microbes are very slow processes that take several weeks and still may not be effective for

industrial textile fiber production (J. Fu, Zhang, Yu, Guebitz, & Cavaco-Paulo, 2012). Chemical

and mechanical/steam explosion processes were not found to be effective, as these processes

may weaken the fiber during delignification resulting in weak and rough fibers (J. Fu, Zhang, et

al., 2012; Rao & Rao, 2007; Rocky & Thompson, 2018a; Witayakran, Haruthaithanasan,

Agthong, & Thinnapatanukul, 2013). The combination of multiple techniques has been found to

be more effective in NBF extraction (Hanana et al., 2015; L. Liu, Cheng, Huang, & Yu, 2012;

Rocky & Thompson, 2018a).

Only a very few bamboo species have been studied for natural fiber extraction. Moso

bamboo (Phyllostachys edulis/pubescens/heterocycla) is the most studied bamboo plant (Afrin,

Kanwar, Wang, & Tsuzuki, 2014; Afrin, Tsuzuki, & Wang, 2009; Chaowana, 2013; Erdumlu &

14

Ozipek, 2008; J. J. Fu et al., 2017; J. Fu, Zhang, et al., 2012; Kim, Okubo, Fujii, & Takemura,

2013; K. Liu et al., 2012; W. Liu et al., 2015; Phong et al., 2012; Sharma, Gatóo, & Ramage,

2015; Tokoro et al., 2008; F. Wang, Shao, Keer, Li, & Zhang, 2015; H. Wang et al., 2015; Xu,

Wang, Liu, & Wu, 2013; Yu et al., 2014). Large size, excellent reproducibility, and higher

growth are some of the major factors that place this species as a top choice. Moso is also widely

used in viscose fiber production (Afrin et al., 2014; Erdumlu & Ozipek, 2008). However, most of

the studies have reported only natural fiber extraction, rather than assessing Moso fiber

applicability in the subsequent processes of apparel manufacturing, such as spinning, weaving or

knitting (Rocky & Thompson, 2018a, 2018c; Yueping et al., 2010). Actually, subsequent

processes with different bamboo species are most often unfeasible because of the poor quality of

the natural bamboo fibers (L. Liu et al., 2012). The natural fibers that have been extracted from

different bamboo plants are reported as very coarse and rough and are not easy to spin even after

blending with other fibers. Only a very few investigations reported yarn and fabric production

(Steffen, Marin, & Müggler, 2013) but as the processes were not commercially feasible, they

were not continued.

Though investigations on Moso bamboo for NBF were not considered entirely successful,

other species may offer better potential for fiber extraction as the quantities of the plant

constituents are not the same in all species. The compositions may even vary with geographic

locations (J. Fu, Li, et al., 2012; Komuraiah, Kumar, & Prasad, 2014; Nayak & Mishra, 2016).

Though there are over 1500 bamboo species of 70-91 genera (Abdul Khalil et al., 2012;

Chaowana, 2013; Correia, Santos, Mármol, Curvelo, & Savastano, 2014; Hardin, Wilson,

Dhandapani, & Dhende, 2009; Kweon, Hwang, & Sung, 2001; Morton, 2005; Nayak & Mishra,

2016; Rai, Ghosh, Pal, & Dey, 2011; Rocky & Thompson, 2018b; Waite, 2010), only a few have

15

been studied for NBF extraction. Therefore, an investigation on several bamboo species that are

also easily available and reproducible for the purpose of NBF extraction is advisable.

It was found that most of the studies started with splitting of the culms, rasping/scraping,

pressing-crimping/crushing/pounding followed by soaking and delignification (Ibrahim et al.,

2015; Kim et al., 2013; L. Liu et al., 2012; Murali Mohan Rao, Mohana Rao, & Ratna Prasad,

2010; Nayak & Mishra, 2016; Rocky & Thompson, 2018a; Steffen et al., 2013; Waite, 2009; Xi,

Qin, An, & Wang, 2013). Steffen et al. (2013) extracted NBF fibers (length = 2 mm—150 mm;

diameter = 4 μm—150 μm; fineness = 5.8 dtex) by mechanical splitting and rasping of culms

followed by repeated enzymatic delignification washing where peroxide was used for bleaching.

Liu et al. (2012) experimented with mechanical and chemical pretreatment using H2SO4 and

NaOH following enzymatic treatment using different enzymes (L. Liu et al., 2012). On the other

hand, Xi et al. (2013) applied alkali degumming followed by acid and water rinsing (Xi et al.,

2013). Extensive mechanical and chemical processes were also studied for NBF extraction for

the purpose of composite structures (Deshpande, Rao, & Rao, 2000; Rao & Rao, 2007). Kim et

al. (2013) investigated the steam explosion, alkali, and chemical extraction of NBF using

different conditions with the result that chemical treatment was found to be better for

delignification (Kim et al., 2013). Zakikhani et al. (2014) extracted NBF for bamboo fiber-

reinforced composites by steam explosion, water and chemical retting (Zakikhani, Zahari,

Sultan, & Majid, 2014). It was concluded that steam explosion produces charred fibers rather

than spinnable natural fibers needed for textiles manufacture (Rocky & Thompson, 2018a;

Zakikhani et al., 2014). Chemical retting with NaOH, zinc nitrate [Zn(NO3)2], and hydrogen

peroxide (H2O2) was reported to be very effective for delignification up to a certain degree

(Zakikhani et al., 2014). Liu et al. (2011) conducted pretreatment by acid (H2SO4) soaking and

16

heating, NaOH treatment and then chemical delignification by using variable concentrations of

different chemicals and conditions. They concluded optimum parameters for NBF extraction by

applying NaOH (20 g/L), Na5P3O10 (3 g/L), Na2SO3 (5 g/L, and a penetrating agent (3 g/L) at

100 °C for 2 h in a liquor ratio of 1:10 (L. Liu, Wang, Cheng, Qian, & Yu, 2011). Therefore, it

can be concluded from previous investigations that a combination of different techniques along

with different chemicals in suitable conditions and processing in multiple steps and repetition of

some steps may help to extract NBF that would be useable in textile and apparel applications.

Although many studies have been performed to extract NBF, only a few studies

attempted a comparative study on extracting fibers from different bamboo species. Phyllostachys

edulis/pubescens/heterocycle (Moso bamboo), Bambusa emeiensis, Bambusa stenostachyum,

Bambusa stenostachyum, Bambusa beecheyama and Dendrocalamus latiflorus are among the

different species considered in different studies (Ibrahim et al., 2015; L. Liu et al., 2012; Tran,

Nguyen, Thuc, & Dang, 2013; Waite, 2010; Witayakran et al., 2013). But none of the

experiments compared more than two species in a single study. This study includes a

comparative study on NBF extraction of four widely available bamboo species and assessment of

yarn and fiber properties.

2.3 Methodology

2.3.1 Materials

Four bamboo species of 1—4 years old Bissetii (Phyllostachys Bissetii), Giant Gray

(Phyllostachys nigra 'henon'), Moso (Phyllostachys edulis/ pubescens) and Red Margin

(Phyllostachys rubromarginata) were provided by Lewis Bamboo, Inc., Oakman, Alabama. Raw

cotton fibers directly from the field were provided by Alabama Cooperative Extension System

(Alabama A&M and Auburn Universities). Chemicals collected from Sigma-Aldrich, USA were:

17

sodium hydroxide/NaOH (beads, AG*), sodium bicarbonate/NaHCO3 (AG), sodium

silicate/Na2SiO3 (RG*), sodium triphosphate/Na5P3O10 (85%, TG*), sodium sulfite/Na2SO3 (≥

98%), acetic acid/CH3COOH (≥ 99%, AG), buffer solution/ [CH3COOH+ CH3COONa] (AG, pH

= 4.6), and zinc nitrate hexahydrate/[Zn(NO3)2•6H2O] (98%, RG). Chemicals provided by VWR

International, LLC, USA: hydrogen peroxide/H2O2 (30% w/w, AG), and sulfuric acid/H2SO4

(95-98%, AG). Chemicals and solutions provided by Consos, Inc. USA: textile softener (Consoft

GPS), scouring agent (Consoscour GSRM), wetting/penetrating agent (Consamine JDA), and

bleaching agent (Consobleach CIL). Fabric washing softener was collected from local Publix

Super Market, Inc., USA (Free & Clear Ultra Fabric Softener).

Note: *AG = ACS (American Chemical Society) grade; *RG = reagent grade; *TG = technical grade.

2.3.2 Apparatus

The major apparatuses used in the study were milling machine/rolling mill (Rolling Mill

Division, Stanat Manufacturing Co. Inc., NY, USA), Reactor and reactor controller (Parr

Instrument Company), Launderometer (AATCC Launder-Ometer, Atlas material testing

Technology LLC), micro-analytical balance (Mettler Toledo 0.00001g XP105DR Dual Range

Semi Micro Analytical Balance Scale), Dryer (GCA corporation, Thelco Precision Scientific

Laboratory Oven, Model 18), conditioning cabinet/Temperature and Humidity Environmental

Test Chamber (Associated Environmental Chamber), Motorized Drum Carder (DCM-405,

Strauch Fiber Equipment Co.), tensile tester (MTS Qtest 25), Ion sputter coater (Leica, MCM-

200 Ion Sputter Coater), SEM (Apreo S HiVac, Thermo Fisher Scientific), and EDS/EDX (JEOL

JSM-7000F, Field Emission Scanning Electron Microscope).

2.3.3 Initial Treatments

All of the samples were processed by splitting of the fresh bamboo culms by 1st crushing,

soaking in either water, NaOH or H2SO4 for 3—5 days at room temperature (RT), and 2nd

18

crushing, and combing with steel combs of various teeth density. Acid soaking with 2 mL/L of

H2SO4 (95—98%) at room temperature for 1-5 days proved to have limited potential. Therefore,

the acid step was discarded and alkali soaking (Recipe 0, Table 2) was applied to all the

approaches during initial processes. All four bamboo species samples were treated separately.

Pretreatments include mechanical and chemical processes (Figure 1).

2.3.4 Delignification

Table 2

List of all recipes used in different processes of natural bamboo fiber (NBF) extraction

Re

cip

e

NaO

H (

g/L

)

NaH

CO

₃ (g

/L)

ᵃH₂O

₂ (m

L/L)

Na₅

P₃O

₁₀ (

g/L

)

Na₂

SO₃

(g/L

)

Na₂

SiO

₃ (m

L/L)

Zn(N

O₃)

₂ (%

ow

m)

ᵇSo

ften

er

(mL/

L)

ᶜSco

ur.

age

nt

(mL/

L)

ᵈBle

ach

ing

agen

t

(mL/

L)

ᵉpen

etra

nt

(mL/

L)

Stee

l bal

l (2

/g o

wm

)

M :

L

(M

ater

ial :

Liq

uo

r)

Tem

per

atu

re X

Tim

e

0* 6

1 : 10 —20

RT x 3-5 days

1 6 6 - - - - - - - - - - 90 °C X 2 h

2 20 - - - - - - - - - - - 90 °C X 3 h 3 6 - - 3 5 - - - - - 3 - 1 : 10

90 °C X 2 h 4 - - - - - - 2 - - - - -

1 : 20 5 5 - - 20 20 20 - - - - - -

6 6 - - - - - - - - - 3 - 1 : 15

7 6 6 4-6 - - - - - - - - - 1 : 10

90 °C X 2-3 h 8 4 4 4 - - - - - - - - -

90 °C X 3 h 9 6 - 6 - - - - - - - - -

10 10-20 - - 5-8 8-10 - - - - - - 2

1 : 15

90 °C X 2.5 h 11 6 - - - - - - 6 4 6 4 2

90 °C X 3.5 h 12 - - 6 - - - - - 3 3 4 -

13 3-5 - 4-9 - - - - 10-20 3-4 3-4 4-5 - 90 °C X 3-8 h 14 2-4 - - - - - - 10 3 3 4 - 90 °C X 3.5 h

15 5-6 - - 10-20 10-15 10-20 - - - - - - 90 °C X 6 h 16 6 6 6 - - - - 20 - - - -

1 : 30 90 °C X 3 h 17 4 4 4 - - - - 15 - - - -

18 3 6 6 - - - - - 3 3 4 - 1 : 15 —20

90 °C X 6-7 h

19 5 - - 10 10 10 - 20 4 4 5 - 1 : 15 90 °C X 8 h

20 5 10 - 5 - 10 - - - - - -

21 2 6 4-6 - - - - - - - - - 1 : 15 —40

90 °C X 1-1.5 h

Notes: RT = room temperature (~21 ± 2)°C; h = hour; owm = on the weight of materials; *involves initial processes; ᵃ30% H₂O₂ ; ᵇFor 2-6 mL/L Consoft GPS and for 10-20 mL/L local fabric washing softener; ᶜConscour GSRM; ᵈConsobleach CIL; ᵉConsamine JDA.

19

Twenty-two different recipes were formulated as shown in Table 2. The M : L or material

to solution ratios or liquor ratios (LR) were between 1:10 to 1:40 depending on the process,

shape or volume of the fiber, size of the container, and effectiveness of the particular recipe. The

setting of temperature and time for processing was varied to find out the better conditions. Either

a reactor controller or Launderometer was employed for delignification by heat treatment using

concentration. A list of the routes of selected samples and total use of NaOH for different

formulae (Table 2). Different chemicals were chosen based on the literature review. Sodium

hydroxide (NaOH) was most often used for delignification in identified studies and it was found

Mechanical Pretreatments

Delignification

Fresh Raw bamboo culms

Chemical Pretreatments

Fiber separation

Lap/Sliver preparation

Spinning (hand spinning)Blending

Test & Analysis

Red Margin (Phyllostachys rubromarginata)

Moso (Phyllostachys edulis)

Giant Gray (Phyllostachys nigra henon)

Bissetii (Phyllostachys bissetii)

Chemical: NaOH, Na2SiO3, Na2CO3,

NaHCO3, [Zn(NO3)26H2O], Na5P3O10, Na2SO3, wetting agent, softener, liquor ratio (M:L), heat treatment, combing

Removing residues & waste fibers

Splitting, scraping woody or

noncellulosic parts, and crushing/

pressing

Mixing/blending with cotton with different ratios

Bleaching: H2O2, NaOH, Na2CO3, softener, scouring

agent, wetting agent,

bleaching agent

Biological: water retting (3-7 days)

Soaking and/or heating: H2SO4, NaOH, water, RT,

drying, combing

Modification

Sorting, mixing, carding, combing

Carding, drawing, doubling

Figure 1. a general flowchart of natural bamboo fiber (NBF)extraction from four bamboo species

using varying conditions.

20

to be the most effective for this purpose. The selection of an appropriate concentration was

extremely crucial, and the higher concentration was not always the best choice for NBF

extraction. A higher concentration could have an adverse effect on fiber length and strength.

Proper LR, processing temperature and time, concentration of other chemicals, mechanical

processes and manual techniques were also very important in the decision of NaOH each route is

given in Table 3. It should be noted here that all four bamboo species samples were treated for

each route separately to compare the suitability of NBF extraction and different properties.

Different NBFs produced from four bamboo samples were tracked using the first letter of each

species (R = Red Margin; B = Bissetii; G = Giant Gray; and M = Moso) followed by numbers.

Each bamboo species was processed for 36 different NBFs extractions (say, R-1 to R-36; B-1 to

B-36). Therefore, all conditions were the same for a particular number with each bamboo initial.

For example, B-25, G-25, M-25, and R-25 NBFs were extracted from four bamboo species

through the same route (Table 3). A general flowchart for all the formulae routes is presented in

Figure 1. The weight of each fiber sample was taken at the beginning and at the end of the route.

As shown in Table 3, only 47 samples out of 144 NBFs were chosen for continued assessments.

After each major treatment with a formula, each sample was subjected to water-washing, drying

and discarding non-spinnable fibers (less than 1.5 cm long). Delignification by water retting for

3-7 days did not prove to be effective.

2.3.5 Modification

The commercial bleaching agent used for textile processing (Consobleach CIL) and/or hydrogen

peroxide was included in different recipes and they were applied more than once in some cases.

When the bleaching agent or peroxide was applied more than one time for some routes, the

NBFs are found to be brighter and whiter. It was also observed that delignification was also

21

better in such cases. The modifications include the use of industrial textile softener and fabric

softener to improve the softness of the NBFs. The addition of softener in different processes

improved delignification but the strength of the fibers seemed to decrease as gauged by

subjective assessment. Hand carding/combing was used to separate coarser fibers from their

bundles as needed.

Table 3

Processing routes of the selected natural bamboo fiber (NBF) samples for different tests and use

of NaOH in each route

Fiber Samples Route Total Use of NaOH,

g/L*

R-1 0 6

R-2 0→1→2 23

R-3 0→1→7 14

R-4 0→1→5 17

R-5 0→1→6 16

R-6 0→1→8 13

R-7 0→1→3 16

R-8 0→4→3 12

R-9 0→2 18

R-10, G-10 0→2→6 24

R-11 0→2→6→7→10 38

R-12 0→4→9 10

G-13 0→3 12

R-14, M-14, G-14 0→3→11 18

R-15 0→11→17 20

R-16, M-16, G-16, B-16 0→10 16-26

R-17 0→1 10

R-18 0→12→16 18

R-19 0→13→16 21

R-20 0→14→16 20

R-21, M-21, G-21, B-21 0→15 11

R-22, M-22, G-22, B-22 0→19 11

M-23, G-23, B-23 0→19→18 14

R-24 0→19→18→14 18

R-25, M-25, G-25, B-25 0→19→18→21 16

R-26 0→20→18→14 18

R-27 0→20→18→21 16

M-28, G-28, B-28 0→15→17 19

*The amounts are converted for an M : L of 1 : 15. In the Table “R” represents Red Margin

bamboo; similarly, B = Bissetii; G = Giant Gray; M = Moso bamboo.

22

2.3.6 Final Treatments

For each of the NBF samples, washing with either warm or cold water, neutralizing with 1—2

mL/L of H2SO4 (95—98%) at 60—80 °C for 30 minutes, and drying were carried out. The fibers

were not neutralized until the last step of the NBF production.

2.3.7 Spinning

Since all NBFs from Bissetii, Giant Gray and Moso had a wide variety of length distribution,

only 3 NBFs (R-23, R-25, and R-27) from Red Margin bamboo were chosen for blending with

raw cotton fibers (RCF). These 3 samples were blended with cotton with different ratios 30%,

40%, 50%, and 60%. The samples were mixed by hand and then carding was done twice to mix

and align the fibers uniformly with a motorized carder to form slivers of 11-15 cm (4.4"-6")

width and 91 cm long (36"). Very coarse, dust, short, damaged and rough fibers were cleaned

and discarded during carding. The NBFs were coarser than RCF and volume of the same mass of

NBFs was lower, that is, the density of bamboo fibers was higher than that of cotton. Since

mixing of fibers is not highly uniform, a coarser count and 2-ply yarn/thread was formed after

hand-spinning of single-ply yarns.

2.3.8 Tests and Assessments

Unless mentioned, all the samples were prepared by preconditioning at standard atmosphere

[temperature (20±2) °C/ (68±4) °F; relative humidity = (65±5) %] as instructed in ASTM D1776

using a conditioning cabinet (ASTM D1776/D1776M−15, 2015).

Measuring Moisture Regain and Content (%)

For moisture regain and content percentages measurement, two similar methods, AATCC TM

20A-2017 and ASTM D629−15 were followed (AATCC 20A-2017, 2018; ASTM D629−15,

2015). By measuring conditioned (wet) weight (𝑊𝑤) and oven-dry weight (𝑊𝑑) of the

23

fibers/fabrics/bamboo, moisture regain percentage (𝑀𝑅) and moisture content percentage (𝑀𝐶)

were calculated by using equation (i) and (ii). The process was repeated at least two times to

acquire consistent values.

𝑀𝐶 =𝐴𝑚𝑜𝑢𝑛𝑡 𝑤𝑎𝑡𝑒𝑟

𝑊𝑡. 𝑜𝑓 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙 𝑏𝑒𝑓𝑜𝑟𝑒 𝑜𝑣𝑒𝑛 𝑑𝑟𝑦𝑖𝑛𝑔× 100% =

𝑊𝑤 − 𝑊𝑑

𝑊𝑤

× 100% … … … … (𝑖)

𝑀𝑅 =𝐴𝑚𝑜𝑢𝑛𝑡 𝑤𝑎𝑡𝑒𝑟

𝑊𝑡. 𝑜𝑓 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙 𝑎𝑓𝑡𝑒𝑟 𝑜𝑣𝑒𝑛 𝑑𝑟𝑦𝑖𝑛𝑔× 100% =

𝑊𝑤 − 𝑊𝑑

𝑊𝑑

× 100% … … … … (𝑖𝑖)

Burning test

The incineration behavior of the raw bamboo and NBFs were tested by the burning test as

AATCC TM 20-2013 (AATCC TM 20-2013, 2018). For this test, a small tuft of the sample (0.1-

2.0 g) was moved by tweezers close to the flame for melting or shrinking, moving to flame for

burning with or without flame, removing from flame for continuous burning or afterglow, and

blowing out the flame for burning, smelling, color, odor and ash properties were observed.

Solubility test

For the solubility test, all samples were tested in test-tubes with 59.5% H2SO4 at 20 °C for 20

min and 70 % H2SO4 at 38 °C for 20 min. For the test, 0.1 g fiber sample was first taken into a

test tube and 10 mL of sulfuric acid solution was added. The sample was shaken and allowed to

set 20 min before observations. This test is AATCC method 20-2013 (AATCC TM 20-2013,

2018). Only H2SO4 was chosen as the fibers were mainly cellulose-based. The test was repeated

twice to check the consistency of the measurement.

Microscopy for Morphology and Diameter

The diameter of the single fibers rather than the average diameter of NBF fiber-bundles samples

were observed. An ion sputter coater was used for gold-coating on fiber samples before taking

images and diameter measurement in SEM (Apreo S) and/or EDS (JEOL 7000) by applying 2

24

kV and 5 kV acceleration voltages respectively. The main purpose of the observation was to

identify the diameter of the natural fibers from different bamboo plants. Since all fibers were

circular or nearly circular in cross-section, at least 100 fibers of each type were measured for

average calculation as directed by standard AATCC and ASTM methods (AATCC 20A-2017,

2018; ASTM D629−15, 2015).

Measuring Fiber Length and Fiber Yield (%)

An average length of each fiber sample was measured manually. For this, a small tuft of fiber

was taken after mixing all fibers uniformly of a specimen and at least 100 fibers were chosen to

measure length by using a line gauge. The average length and standard deviation were calculated

for each sample. The fibers with a length smaller than 0.5 cm were discarded (not measured).

Any fiber above 1.5 cm was considered as spinnable.

The yield percentage was defined as the amount of cellulose-rich fibrous materials that

was extracted from raw bamboo samples by measuring oven-dry weight in each of the cases. The

oven-dry weight of raw bamboo or the specimen at the beginning of the step-process (𝑊𝑏) and

the oven-dry weight of the finished fiber at the end of the process (𝑊𝑓) were measured to

calculate the percentage of fiber yield (𝐹𝑌) by using equation (iii).

𝐹𝑌 =𝑊𝑏 − 𝑊𝑓

𝑊𝑏

× 100% … … … … … … … … … … … … . . (𝑖𝑖𝑖)

Measuring Fiber Fineness

A micro-analytical balance was employed to measure microgram (μg) mass of fibers. Since the

balance was not highly sensitive to small masses, several fibers were weighted at a time and total

length of the fibers was used as the length for that particular mass. Then fineness was measured

in terms of Tex (direct count) and Ne (indirect/cotton/English count) where Tex is a gram mass

of fiber/yarn per 1000 m length and Ne is a number of hanks (1 hank = 840 yards) of 1 lb

25

fiber/yarn. The conversion was calculated as mentioned in ASTM D6587 (ASTM D6587−12,

2012).

Testing Tensile Properties

Though ASTM D2256M was employed for measuring tensile properties of selected longer NBF

fibers and yarns by using MTS Qtest tensile tester, there were some changes in the procedure and

parameters (ASTM D2256/D2256M, 2015). A constant rate of elongation was applied with a

crosshead speed of 10-30 cm/min for yarns and 10 mm/min for fibers to maintain minimum

time-to-break no less than 20 seconds. The gauge length or fiber length was measured from grip

to grip point of the tester and the length was 25 cm for yarns and 20 cm for fibers. Different load

cells were chosen for fiber (500 lb) and yarns (5 or 500 lb).

2.4 Results and Discussions

2.4.1 Discussions on Natural Bamboo Fibers Extraction

Bissetii was the smallest bamboo plant among the four species when considering length and

diameter (Table 4). The Red Margin bamboo culms had the greatest length and highest moisture

content. The length and diameter did not have a direct relationship with extraction processes,

however, the fresh culms with higher moisture proved to be easier in splitting, crushing and

Table 4

Moisture/water content (%) of culms from four fresh bamboo plants

Bamboo

plant

Length of culms,

cm

The diameter of

culms, cm

Moisture content

(%)

Dry weight

(%)

Bissetii 16.5—25.4 1.5—2.3 32.16 67.84

Giant Gray 18.4—27.9 4.8—5.1 23.65 76.35

Moso 17.3—30.5 1.8—5.3 30.35 69.65

Red Margin 31.8—43.8 2.5—3.6 37.91 62.09

immediate combing. In this respect, the Giant Gray was inferior among the 4 species in

preprocessing. After splitting, the length of the Giant Gray fibers gradually decreased as it went

26

through different extraction processes. Again, the rate of breakage and shorter fiber production

were higher for the culms with lower moisture content. Therefore, as the extraction processes

Raw Bamboo (Red Margin) B-23 (from Bissetii) G-23 (from Giant Gray

M-23 (from Moso) R-9 (from Red Margin) R-23 (from Red Margin)

R-25 (from Red Margin) lap/sliver NBF/cotton (40/60) Hand spun yarn NBF/cotton (50/50)

Figure 2. Photographs of the natural bamboo fibers (NBFs) from four bamboo plants and hand-

carded yarn blended with cotton fiber.

progressed in a particular route, Bissetii, Giant Gray and Moso produced shorter fibers than that

of Red Margin and the NBFs were also more inconsistent in these 3 species (Figure 2). For

example, though extracted through the same route, the NBFs B-23, G-23, and M-23 were almost

the same (coarser, shorter, rough fibers) but R-23 was finer, longer, softer and had more

consistent fiber (Figure 2). It was also possible to produce long (~33 cm) and flax-like fiber (R-

27

9) from the Red Margin. A shiny, highly uniform, spinnable fiber was also extracted from Red

Margin as shown R-25 in Figure 2.

2.5 Moisture Regain and Content

Figure 3. Comparison of moisture regain (%) and moisture content (%) of conventional fibers,

bamboo, and natural fibers. [Note: BV = bamboo viscose; 70% BVC = 70% BV and 30% cotton;

95% BVS = 95% BV and 5% spandex; 70% BVCS = 70% BV, 25% cotton and 5% spandex;

40% BVCS = 40% BV, 55% cotton and 5% spandex; RF = 100% regular rayon fabric; UCF =

untreated 100% cotton fabric; RCF = 100% raw cotton fiber; R, M, G and B = natural bamboo

fibers from Red Margin, Moso, Giant Gray and Bissetii bamboo plants.]

MR% or MC% affects comfortability and mechanical properties of the fibers. A fabric

with higher MR% is more comfortable. Moreover, a higher MR% decreases the flammability of

the materials and promotes some processes such as scouring, bleaching and dye absorption.

Bamboo fiber had a round shape and there are many void spaces in-between where the fibers are

28

packed together. These voids promote a larger amount of moisture retention showing higher

content. Bamboo viscose and conventional viscose both are reported to be more moisture

absorbent than tencel (Waite, 2010). Figure 3 shows a comparison of moisture regain

percentages (MR%) and content percentages (MC%) of some conventional fibers, bamboo strips,

and NBF fibers. It was found that rayon and bamboo viscose were similar and the highest

average MR% (~11%) and MC% (~10%) among all samples. All four bamboo dried strips and

NBFs showed similar values of MR% and MC% among themselves but higher than raw or

bleached cotton fibers. The raw dried bamboo plants showed an average of about 8% MR%

(8.16%) and of about 7.5 MC% (7.55%). Similarly, the NBFs showed an average of about 8%

MR% (8.02%) and of about 7.5 MC% (7.42%). Though the moisture content of fresh bamboo

plants had different values, dried bamboo plants and NBFs showed similar values.

2.6 Incineration Behavior (Burning Test)

Table 5

Burning tests and observations of different conventional fibers, raw bamboo, and natural

bamboo fiber (NBF) samples

Sample Near Flame in flame removed from flame odor ash/residue

Bamboo viscose

burns the surface,

ignites quickly

burns quickly, yellow flame

continues to burn, afterglow

burning paper

black feathery ash with some white

spots

Rayon Burns quickly,

yellow flame, lots of white smoke

continues to burn, slight afterglow

black feathery ash mottled with grey

Untreated/ Raw cotton

burns quickly, yellow flame

continues to burn, afterglow

light and feathery, grayish, no black

Polyester fuses and

shrinks away melts and burns

slowly burns with difficulty

chemical smell

Hard, black, round bead

Bissetii Raw Burns the surface,

ignites slowly burns quickly, yellow flame

continues to burn for few moments and then

stops, afterglow

burning paper

Gray and slightly black Red Margin Raw

Moso Raw Burns the surface when

very close, ignites slowly

Biomass ash

Black Giant Gray Raw

All NBF fibers

from four

bamboo plants

Burns the surface,

ignites quickly

burns quickly, yellow flame, white smoke

either stops after few moments or continues

to burn, afterglow

burning paper

Dark-grayish to black or grayish to black

29

Incineration behavior of different conventional fibers along with bamboo and NBFs are

summarized in Table 5. Almost all of the fibers ignite quickly near the flame and the surfaces

were burnt gradually with yellow flames. Most of the fibers emitted white smoke during or after

incineration. When removed from the flame, the fibers with coarser forms or a higher non-

fibrous content stopped burning after a shorter period than the fibers with finer forms or with

less non-fibrous content. There was afterglow in almost all cases. The odor of the burnt fibers

smelt like burning paper or burning ashes of biomass. As the non-fibrous contents were lower or

removed in NBFs, the ash/residue was black for coarser fibers to dark grayish and then to

grayish in case of finer fibers. So, a higher amount of non-fibrous content provided a darker

blackish appearance to the ashes. The weight of the ashes was higher for the fibers with a greater

diameter or higher non-fibrous content.

2.7 The Solubility of Bamboo and NBF

The observations on the solubility of bamboo viscose, rayon, cotton, polyester, dried raw

bamboo specimens, and NBFs in sulfuric acid are summarized in Table 6. Though bamboo

Table 6

Solubility test of different conventional fibers, raw bamboo and natural bamboo fiber (NBF)

samples in sulfuric acid

Sample 59.5 % H2SO4×20 °C×20' 70 % H2SO4×38 °C×20'

Bamboo viscose Completely soluble Dissolved completely

Rayon

Cotton Mostly soluble with some small particles Dissolved completely

Polyester Completely insoluble Completely insoluble

Red Margin Raw

Partially dissolved forming darker black/brown solution and

turn the masses into dark black

Partially dissolved, black undissolved mass

and brown solution

Moso Raw

Giant Gray Raw

Bissetii Raw

All NBFs Slightly dissolved and turned the mass into black and

formed black solution

Mostly dissolved but there was a little mass

left undissolved, darker black solution

viscose and rayon dissolved completely in 59.5% and 70% H2SO4 solutions, none of the raw

bamboo specimens or NBFs were completely dissolved. There was always black/dark brown

30

mass left undissolved with a black/dark brown solution for raw bamboo and NBF specimens.

Such behaviors were also unlike raw or bleached cotton and polyester.

2.8 Microscopic Analyses

2.8.1 The diameter of the Single Natural Bamboo Fibers

Mean, maximum and minimum diameters of the single bamboo fibers from four bamboo plants

are represented in Figure 4. Though microscopic images showed some fibers were in bundle

form, diameters of the single fibers were observed to identify standard values for bamboo fibers.

Figure 4. The diameter of the single natural bamboo fibers from four bamboo plants.

It was found that fibers from Moso were larger in diameter than that of other plants. The average

values for Moso were within 10—13 μm. These values were consistent with other observations

of 4-20 μm (Afrin et al., 2014; Komuraiah et al., 2014; Rocky & Thompson, 2018c; Steffen et

al., 2013). Though there was a wide variety in maximum diameters, minimum diameters were

within 4-6 μm. The standard deviation was between 2.00-4.73 μm for all observations.

2.8.2 Morphology

When raw bamboo strips were analyzed as in Figure 5 (a-d), it was found that all four bamboo

species have similar structures where fibers are bonded and covered by lignin

9.5

1

12

.25

5.1

6

10

.41

17

.17

4.5

4

13

.10

21

.55

5.6

7

10

.45

14

.5

4.7

1

11

.42 2

0.7

4.0

4

0

2

4

6

8

10

12

14

16

18

20

22

Mean diameter (μm) Maximum diameter (μm) Minimum diameter (μm)

R-9 R-27 M-22

G-23 B-23

31

(a) Raw Bissetii (1000X) (b) Raw Giant Gray (1000X) (c) Raw Moso (1000X)

(d) Raw Red Margin (1000X) (e) B-23 NBF (2000X) (f) G-23 NBF (1000X)

(g) M-22 NBF (2000X) (h) R-9 NBF (950X) (i) R-25 NBF (2000X)

Figure 5. SEM images of four raw bamboo strips and natural bamboo fibers (NBFs) taken by

JEOL 7000 (a—d, h) and Apreo S (e—g, i).

and other non-fibrous materials. However, investigation of chemical compositions would

confirm if they have similar composition and structures. When fibers were extracted by

removing lignin and other non-fibrous elements as shown in Figure 5 (e-i), NBFs are almost

round or cylindrical in shape. The cross-section of the bamboo fibers were found to be round and

circular solid in shape but some cross-sections had broken lines or cracks resulted from different

32

processes. It is also clear that there was an amount of non-fibrous materials in the NBFs (Figure

5g-5i) that can provide some natural properties of bamboo plants.

2.9 Fiber Length and Yield Percentage

Since 36 different routes were executed for NBFs extraction from four bamboo species, a list of

selected fibers with their respective mean, maximum, minimum length along with fiber yield

percentages are represented in Table 7. Since the different spans of fiber length can be selected

for different purposes, such as spinning type, type of yarn (coarse or fine, based on spinning

processes), composite application, and so on, this list can provide us with information for a

prospective route for NBF extraction. Some NBFs in Table 7 had higher standard deviation

values, meaning that fiber of such type had wide Gaussian distribution and would not be good

for spinning of high-quality yarns. NBFs from Red Margin showed smaller standard deviation

values which indicated that such fibers were more uniform. The longest NBFs produced after the

9th and 10th routes from Red Margin were 33.38±10.08 cm (13.14±3.97 inches) and 37.10±12.22

cm (14.61±4.81 inches) where fiber yield percentages were also very high: 77.08% and 70.14%

respectively. Any use of such fibers would have excellent potential for textile production based

on these measured factors. A moderate delignification process such as enzymatic or microbial

may help to produce more uniform, strong and long NBFs. These fibers became finer in

subsequent processing but lost length, strength, and uniformity along with fiber yield

percentages, for example, R-11 (Table 7). NBFs with a prospect of textile uses had no less than

40% yield. NBFs extracted by routes 23rd and 25th were shorter but within the spinnable limit.

The lengths of NBFs (R-23 and M-23) and yield % (52.69% and 53.24%) were higher for Red

Margin and Moso than that of Giant Gray and Bissetii.

33

Table 7

Lengths and yield percentages of natural bamboo fibers (NBFs) of four bamboo species

extracted through different techniques and routes

Sample Min. length Max. length Avg. Length Total

steps

Fiber Yield,

%

Total NaOH,

g/L cm inch cm inch cm inch

R-1 3.00 1.18 44.00 17.32 27.94±14.8 11±5.83 2 90.21 6

R-4 1.50 0.59 22.50 8.86 12.46±9.07 4.91±3.57 3 - 17

R-5 1.50 0.59 19.50 7.68 4.90±3.56 1.93±1.40 3 - 16

R-6 1.50 0.59 15.00 5.91 4.39±8.23 1.73±3.24 3 69.09 13

R-7 2.50 0.98 26.00 10.24 11.7±7.27 4.61±2.86 3 72.80 16

R-8 2.00 0.79 14.00 5.51 5.82±3.17 2.29±1.25 3 38.33 12

R-9 10.00 3.94 43.00 16.93 33.38±10.08 13.14±3.97 3 77.08 18

R-10 13.50 5.31 50.00 19.69 37.10±12.22 14.61±4.81 4 70.14 24

R-11 2.50 0.98 21.00 8.27 8.08±4.37 3.18±1.72 6 14.74 38

R-12 2.50 0.98 18.00 7.09 7.42±4.75 2.92±1.87 4 70.98 10

R-14 1.50 0.59 9.00 3.54 5.52±2.19 2.17±0.86 4 47.29 18

R-15 2.00 0.79 8.00 3.15 4.01±1.63 1.58±0.64 4 0.00 20

R-16 2.30 0.91 19.00 7.48 14.03±5.04 5.52±1.98 2 57.87 16

R-17 3.50 1.38 21.00 8.27 10.23±5.17 4.03±2.04 3 62.53 10

R-18 1.50 0.59 30.00 11.81 9.20±4.98 3.62±1.96 4 56.46 18

R-19 1.50 0.59 34.00 13.39 6.94±6.62 2.73±2.61 4 24.59 21

R-20 2.50 0.98 18.00 7.09 7.06±3.46 2.78±1.36 4 23.21 20

R-21 1.50 0.59 45.00 17.72 20.33±18.7 8.00±7.36 3 61.04 11

R-22 4.00 1.57 32.00 12.60 11.44±8.16 4.50±3.21 3 59.87 11

R-23 1.50 0.59 22.50 8.86 6.90±5.40 2.72±2.13 4 52.69 14

R-25 2.00 0.79 11.00 4.33 4.41±2.78 1.74±1.09 5 46.54 16

R-26 0.50 0.20 3.50 1.38 1.72±0.92 0.68±0.36 5 20.39 18

R-27 1.50 0.59 21.50 8.46 6.68±6.00 2.63±2.36 5 44.97 16

M-16 1.50 0.59 11.00 4.33 5.27±2.96 2.08±1.17 2 51.60 20

M-21 1.50 0.59 31.30 12.32 7.00±5.40 2.76±2.13 2 68.15 11

M-22 3.00 1.18 20.00 7.87 8.89±4.29 3.5±1.69 2 68.97 11

M-23 1.50 0.59 23.00 9.06 5.05±5.22 1.99±2.06 3 53.24 14

M-25 0.50 0.20 4.00 1.57 1.54±0.86 0.61±0.34 4 45.63 16

M-28 1.50 0.59 8.00 3.15 3.71±1.97 1.46±0.78 3 48.73 19

G-10 2.00 0.79 13.00 5.12 4.68±2.75 1.84±1.08 4 66.29 24

G-13 1.20 0.47 23.80 9.37 7.25±5.56 2.85±2.19 3.00 62.48 12

G-14 Almost all fibers were less than 1.5 cm 4 48.24 18

G-16 1.50 0.59 8.00 3.15 3.40±1.56 1.34±0.61 3 46.36 26

G-21 1.50 0.59 12.00 4.72 3.72±2.77 1.46±1.09 3 62.26 11

G-22 1.90 0.75 14.50 5.71 5.56±3.94 2.19±1.55 3 56.00 11

G-23 1.00 0.39 6.50 2.56 2.83±1.80 1.12±0.71 4 42.67 14

G-25 0.50 0.20 3.50 1.38 1.19±0.68 0.47±0.27 5 37.51 16

G-28 1.00 0.39 5.00 1.97 1.60±0.91 0.63±0.36 4 41.46 19

B-16 1.50 0.59 17.00 6.69 4.22±3.33 1.66±1.31 2 40.82 26

B-21 1.50 0.59 4.50 1.77 2.6±0.83 1.02±0.33 2 60.97 11

B-22 2.50 0.98 21.00 8.27 6.72±4.83 2.65±1.9 2 59.14 11

B-23 1.50 0.59 6.00 2.36 3.57±1.51 1.41±0.59 3 43.06 14

B-25 0.50 0.20 4.00 1.57 1.66±0.87 0.66±0.34 4 35.74 16

B-28 0.50 0.20 3.00 1.18 1.52±0.83 0.6±0.33 3 41.34 19

34

NBFs from Red Margin was overall better in length, uniformity and yield percentages.

Though the finest diameter fibers were extracted by the 25th route for all four bamboo plants, R-

25 from Red Margin was only spinnable with an average length of 4.41±2.78 cm (1.74±1.09

inches) and yield of 46.54%. Though the length of the NBFs was not directly related to the

overall use of NaOH as shown in Figure 6, it was observed that high use of NaOH in a particular

process would either damage the fibers or produce very short but non-uniform fibers. Since

Figure 6. The relationship among fiber lengths, yield percentages and total use of NaOH in

natural bamboo fiber (NBF) extraction.

NaOH was applied in multiple steps and at different stages of the NBFs extraction, the NBFs

treated with less overall NaOH performed better in length, strength, and uniformity, than NBFs

with higher usage of NaOH in some cases. Yield percentages were weakly related to the overall

application of NaOH such as a higher NaOH usage led to a lower yield of final fibers (Figure 6).

35

2.10 Fiber Fineness

Since the fiber fineness (linear density) was measured by manual methods using a microbalance

with some difficulty, the NBF samples that appeared prospective for different uses were selected

for assessments. A summary of fiber fineness of different NBFs in Tex and Ne is presented in

Table 8. Though listed linear densities of NBFs of 9.68—93.3 Tex are higher than cotton fibers

of 0.05—0.20 Tex (Altaş & Kadoǧlu, 2006; Y. Liu, Thibodeaux, & Rodgers, 2014), they can be

used for coarser yarns or can be modified into finer counts by further modifications. Moreover,

Table 8

The fineness of the natural bamboo fibers (NBFs) extracted from four bamboo plants

Sample Fiber count in Ne Fiber count in Tex

Average Maximum Minimum Average Maximum Minimum

R-1 16.82±11.41 34.84 1.02 35.09±23.81 577.68 16.95

R-9 21.75±11.18 38.61 6.65 27.15±13.96 88.74 15.29

R-10 35.48±22.52 92.51 9.58 16.65±10.57 61.62 6.38

R-21 39.29±23.43 91.53 14.36 15.03±8.96 41.11 6.45

R-27 42.55±31.81 110.72 3.13 13.88±10.38 188.78 5.33

M-21 6.33±4.63 15.86 0.32 93.3±68.24 1825.40 37.22

M-22 17.4±16.82 49.21 0.73 33.94±32.81 803.84 12.00

M-25 32.47±25.64 74.56 2.95 18.19±14.36 200.40 7.92

G-21 35.17±25.90 83.65 6.58 16.79±12.37 89.75 7.06

G-23 46.68±34.34 138.40 12.42 12.65±9.31 47.53 4.27

G-25 61.03±45.36 119.29 9.84 9.68±7.19 60.00 4.95

B-16 27.24±25.15 78.15 0.71 21.68±20.02 836.25 7.56

B-23 28.66±24.13 73.81 3.36 20.61±17.35 175.69 8.00

B-25 32.68±17.00 61.33 8.27 18.07±9.40 71.43 9.63

most of the NBFs from Red Margin were longer than cotton fibers. So, they can be further

modified at the expense of losing some length or they can be used as they are for specific

purposes. It should also be mentioned that specialized machines for carding, combing and other

processes were not employed for NBFs extraction. Hence it might be possible to extract even

better fiber for fineness, length, strength, and spinnability with advanced specialized

technologies.

36

2.11 Tensile Properties

The breaking tenacity of NBFs was found to be very high when the maximum length was

retained (22—36 cm) with 28—37 Tex of linear density. For example, breaking tenacity of R-9

and R-10 was 138.63±56.80 N/Tex and 63.74±64.27 N/Tex respectively (Table 9). The NBFs

exhibited a breaking elongation of 2.06—2.46% which is comparable with other studies of 1.4—

2.9% (L. Liu et al., 2011; Prasad & Rao, 2011; Sanjay et al., 2018; Steffen et al., 2013) but lower

than cotton fibers 4—8% (Fiori, Sands, Little, & Grant, 1956; Yang & Gordon, 2016). It should

Table 9

Breaking tenacity and elongation of natural bamboo fibers and cotton-blended yarns

Sample Combination

Composition Fineness Breaking tenacity Breaking

elongation

%/% (M ± σ)

Ne (M ± σ)

Tex (M ± σ) Kg/Tex

(M ± σ) N/Tex

(M ± σ) %

NBF-1 R-9 100 22±11 37±19 141.31±57.90 138.63±56.80 2.46±0.52

NBF-2 R-10 100 36±23 28±19 64.97±65.51 63.74±64.27 2.06±0.76

SP yarn R-23/RCF 50/50 0.69±0.05 428±31 2.51±0.67 2.46±0.65 7.76±1.94

DP yarn 1 R-27/BCF 40/60 0.76±0.06 786±58 2.40±0.62 2.36±0.61 10.24±2.00

DP yarn 2 R-25/BCF 40/60 0.67±0.04 888±55 1.99±0.56 1.95±0.55 9.76±2.26

DP yarn 3 R-27/RCF 50/50 0.55±0.02 1066±43 2.29±0.54 2.24±0.53 10.78±1.44

DP yarn 4 R-23/RCF 50/50 0.69±0.05 855±61 2.13±0.46 2.09±0.45 10.89±2.53

DP yarn 5 R-25/BCF 60/40 0.75±0.04 795±43 1.62±0.33 1.58±0.32 8.51±1.15

DP yarn 6 R-25/BCF 70/30 0.56±0.02 1057±30 1.54±0.45 1.51±0.44 9.29±1.29

Note: R = natural bamboo fiber (NBF) from Red Margin; SP =single-ply; DP = double-ply; RCF/BCF = raw/bleached cotton fiber; M = mean value; σ = standard deviation.

be noted that tensile properties of NBF of the other three species and shorter fibers were not

determined as they were out of available machine capacity. But it was observed that breaking

tenacity and elongation of the yarns decreased when the amount of NBF increased in the blend.

This means that the NBFs shared lower strength in the yarns than that of cotton fibers. Since the

yarns were not produced by industrial techniques that would provide a higher number of twists,

and uniform mixing, the current yarn might not convey all the potential of the fibers in yarn

37

usage. It was noticeable that yarns (7.76—10.89%) showed higher breaking elongations than

NBFs (2.06-2.46%) and double-ply yarns, such as DP yarn 4 with 10.89%, showed higher than

single-ply (SP yarn with 7.76%) for similar blends (Table 9).

2.12 Conclusions

This study provides a list of different routes for natural bamboo fiber (NBF) extraction where

total use of chemicals was within 6-38 g/L on the weight of initial raw bamboo throughout the

particular route. The 25th formula was found to be most effective for extracting spinnable fibers,

especially from Red Margin (R-25). The NBFs of this group were produced using overall 16 g/L

of NaOH and the fibers were uniform, fine and spinnable with cotton blend. However, several

routes were effective to yield of NBFs that were useable for textiles. The selection of the best

route will depend on what kind of NBFs and their properties are required. Some routes were

good for long but coarse fiber, some were good for fine but shorter fiber, some were good for

retaining high strength, and some were only good for overall fiber yield. Different chemicals

were studied where some chemicals were found to be very useful for NBF extraction such as

NaOH, NaHCO3, H2O2, and penetrating agent; some were moderately useful such as Na5P3O10,

Na2SO3, and Na2SiO3; and some were either not useful or used for neutralization such as

CH3COOH, H2SO4, and Zn(NO3)2. Yarns were produced by hand spinning after blending with

cotton at different ratios. Advantages of extraction processes, moisture regain and content,

incineration behavior, solubility, the effect of NaOH, length, diameter fiber yield, fineness,

spinnability, and tensile properties were compared. Moisture regains and contents of the natural

bamboo fibers (NBFs) were not found in the literature. So, this study on four bamboo species

and NBFs provides some much needed information. Moisture regain of the NBFs was found to

be higher than cotton; this is indicative of better comfortability in clothing. Similarly, reports on

38

diameter (10—13 μm), fiber yield for prospective NBFs (40-77%), breaking tenacity and

elongation of NBFs and yarns in this study provide a baseline for future research. The analyses

on the surface morphology of four bamboo species and their NBFs by two microscopic

instruments (SEM and EDS) are also summarized where an explanation is provided why the

NBFs may have natural properties from bamboo plants. Moreover, this study provides a

comparison of some properties such as moisture regain, moisture contents, incineration behavior,

and solubility among bamboo, NBFs, bamboo viscose, cotton, and some conventional fibers.

Future research of more species, different age-group of species, introducing enzymes or

microbes in intermediate steps of extraction, and developing special equipment and technologies

specific to bamboo fiber extraction would be necessary to establish textiles from natural bamboo

fibers.

2.13 References

AATCC 20A-2017. (2018). Fiber Analysis: Quantitative. American Association of Textile

Chemists and Colorists, AATCC. PO Box 12215, Research Triangle Park, N. C. 27709,

USA.

AATCC TM 20-2013. (2018). Fiber Analysis: Qualitative. American Association of Textile

Chemists and Colorists, AATCC. PO Box 12215, Research Triangle Park, N. C. 27709,

USA. https://doi.org/10.1201/9781420038064.ch4

Abdul Khalil, H. P. S., Bhat, I. U. H., Jawaid, M., Zaidon, A., Hermawan, D., Hadi, Y. S., …

Hadi, Y. S. (2012). Bamboo fibre reinforced biocomposites: A review. Materials and

Design, 42, 353–368. https://doi.org/10.1016/j.matdes.2012.06.015

Afrin, T., Kanwar, R. K., Wang, X., & Tsuzuki, T. (2014). Properties of bamboo fibres produced

using an environmentally benign method. Journal of the Textile Institute, 105(12), 1293–

1299. https://doi.org/10.1080/00405000.2014.889872

Afrin, T., Tsuzuki, T., & Wang, X. (2009). Bamboo fibres and their unique properties. In

Natural fibres in Australasia: proceedings of the combined (NZ and AUS) Conference of

The Textile Institute, Dunedin 15-17 April 2009 (pp. 77–82). Dunedin: Textile Institute

(NZ).

Altaş, S., & Kadoǧlu, H. (2006). Determining fibre properties and linear density effect on cotton

yarn hairiness in ring spinning. Fibres and Textiles in Eastern Europe, 14(3(57)), 48–57.

39

ASTM D1776/D1776M−15. (2015). Standard Practice for Conditioning and Testing Textiles.

Annual Book of ASTM Standards. https://doi.org/10.1520/D1776_D1776M-15

ASTM D2256/D2256M. (2015). Standard Test Method for Tensile Properties of Yarns by the

Single-Strand Method. Annual Book of ASTM Standards.

https://doi.org/10.1520/D2256_D2256M-10R15

ASTM D629−15. (2015). Standard Test Methods for Quantitative Analysis of Textiles. Annual

Book of ASTM Standards. https://doi.org/10.1520/D0629-15

ASTM D6587−12. (2012). Standard Test Method for Yarn Number Based on Short-Length

Specimens. Annual Book of ASTM Standards. https://doi.org/10.1520/D6587-12

Chaowana, P. (2013). Bamboo: An Alternative Raw Material for Wood and Wood-Based

Composites. Journal of Materials Science Research, 2(2), 90–102.

https://doi.org/10.5539/jmsr.v2n2p90

Correia, V. D. C., Santos, S. F., Mármol, G., Curvelo, A. A. D. S., & Savastano, H. (2014).

Potential of bamboo organosolv pulp as a reinforcing element in fiber-cement materials.

Construction and Building Materials, 72, 65–71.

https://doi.org/10.1016/j.conbuildmat.2014.09.005

Deshpande, A. P., Rao, M. B., & Rao, C. L. (2000). Extraction of Bamboo Fibers and Their Use

as Reinforcement in Polymeric Composites. Journal of Applied Polymer Science, 76, 83–

92.

Erdumlu, N., & Ozipek, B. (2008). Investigation of Regenerated Bamboo Fibre and Yarn

Characteristics. Fibres & Textiles in Eastern Europe, 16(4), 43–47.

Fiori, L. A., Sands, J. E., Little, H. W., & Grant, J. N. (1956). Effect of Cotton Fiber Bundle

Break Elongation and Other Fiber Properties on the Properties of a Coarse and a Medium

Singles Yarn. Textile Research Journal, 26(7), 553–564.

Fu, J. J., Shen, S., Duan, J. L., Tang, C., Du, X. Y., Wang, H. B., & Gao, W. D. (2017).

Microwave heating: A potential pretreating method for bamboo fiber extraction. Thermal

Science, 21(4), 1695–1699. https://doi.org/10.2298/TSCI160615055F

Fu, J., Li, X., Gao, W., Wang, H., Cavaco-Paulo, A., & Silva, C. (2012). Bio-processing of

bamboo fibres for textile applications: a mini review. Biocatalysis and

Biotransformation, 30(1), 141–153. https://doi.org/10.3109/10242422.2012.650450

Fu, J., Zhang, X., Yu, C., Guebitz, G. M., & Cavaco-Paulo, A. (2012). Bioprocessing of bamboo

materials. Fibres and Textiles in Eastern Europe, 90(90), 13–19.

Hanana, S., Elloumi, A., Placet, V., Tounsi, H., Belghith, H., & Bradai, C. (2015). An efficient

enzymatic-based process for the extraction of high-mechanical properties alfa fibres.

Industrial Crops and Products, 70, 190–200.

https://doi.org/10.1016/j.indcrop.2015.03.018

40

Hardin, I. R., Wilson, S. S., Dhandapani, R., & Dhende, V. (2009). An assessment of the validity

of claims for “bamboo” fiber. AATCC Review, 9(10), 33–36.

Hebel, D. E., Javadian, A., Heisel, F., Schlesier, K., Griebel, D., & Wielopolski, M. (2014).

Process-controlled optimization of the tensile strength of bamboo fiber composites for

structural applications. COMPOSITES PART B, 67(October 2013), 125–131.

https://doi.org/10.1016/j.compositesb.2014.06.032

Hu, Y., & Yu, W. (2014). Effects of Acid Dye on the Performance of Bamboo- based Fiber

Composites. BioResources, 9(4), 6141–6152.

Ibrahim, I. D., Jamiru, T., Sadiku, R. E., Kupolati, W. K., Agwuncha, S. C., & Ekundayo, G.

(2015). The use of polypropylene in bamboo fibre composites and their mechanical

properties– A review. Journal of Reinforced Plastics and Composites, 34(16), 1347–

1356. https://doi.org/10.1177/0731684415591302

Kim, H., Okubo, K., Fujii, T., & Takemura, K. (2013). Influence of fiber extraction and surface

modification on mechanical properties of green composites with bamboo fiber. Journal of

Adhesion Science and Technology, 27(12), 1348–1358.

Komuraiah, A., Kumar, N., & Prasad, B. (2014). Chemical Composition of Natural Fibers and its

Influence on their Mechanical Properties. Mechanics of Composite Materials, 50(3),

359–376.

Kweon, M. H., Hwang, H. J., & Sung, H. C. (2001). Identification and antioxidant activity of

novel chlorogenic acid derivatives from bamboo (Phyllostachys edulis). Journal of

Agricultural and Food Chemistry, 49(10), 4646–4655. https://doi.org/10.1021/jf010514x

Liu, K., Takagi, H., Osugi, R., & Yang, Z. (2012). Effect of physicochemical structure of natural

fiber on transverse thermal conductivity of unidirectional abaca/bamboo fiber

composites. Composites Part A: Applied Science and Manufacturing, 43(8), 1234–1241.

https://doi.org/10.1016/j.compositesa.2012.02.020

Liu, L., Cheng, L., Huang, L., & Yu, J. (2012). Enzymatic treatment of mechanochemical

modified natural bamboo fibers. Fibers and Polymers, 13(5), 600–605.

https://doi.org/10.1007/s12221-012-0600-3

Liu, L., Wang, Q., Cheng, L., Qian, J., & Yu, J. (2011). Modification of natural bamboo fibers

for textile applications. Fibers and Polymers, 12(1), 95–103.

https://doi.org/10.1007/s12221-011-0095-3

Liu, W., Xie, T., Qiu, R., & Fan, M. (2015). N-methylol acrylamide grafting bamboo fibers and

their composites. Composites Science and Technology, 117, 100–106.

https://doi.org/10.1016/j.compscitech.2015.06.005

Liu, Y., Thibodeaux, D., & Rodgers, J. (2014). Preliminary Study of Linear Density, Tenacity,

and Crystallinity of Cotton Fibers. Fibers, 2(3), 211–220.

https://doi.org/10.3390/fib2030211

41

Morton. (2005). Extent and characteristics of bamboo resources. World Bamboo Resources – a

Thematic Study Prepared in the Framework of the Global Forest Resources Assessment

2005, 11–30.

Murali Mohan Rao, K., Mohana Rao, K., & Ratna Prasad, A. V. (2010). Fabrication and testing

of natural fibre composites: Vakka, sisal, bamboo and banana. Materials and Design,

31(1), 508–513. https://doi.org/10.1016/j.matdes.2009.06.023

Nayak, L., & Mishra, S. P. (2016). Prospect of bamboo as a renewable textile fiber, historical

overview, labeling, controversies and regulation. Fashion and Textiles, 3(2), 1–23.

https://doi.org/10.1186/s40691-015-0054-5

Phong, N. T., Fujii, T., Chuong, B., & Okubo, K. (2012). Study on How to Effectively Extract

Bamboo Fibers from Raw Bamboo and Wastewater Treatment. Journal of Materials

Science Research, 1(1), 144–155. https://doi.org/10.5539/jmsr.v1n1p144

Prasad, A. V. R., & Rao, K. M. (2011). Mechanical properties of natural fibre reinforced

polyester composites: Jowar, sisal and bamboo. Materials and Design, 32(8), 4658–4663.

https://doi.org/10.1016/j.matdes.2011.03.015

Rai, V., Ghosh, J. S., Pal, A., & Dey, N. (2011). Identification of genes involved in bamboo fiber

development. Gene, 478(1–2), 19–27. https://doi.org/10.1016/j.gene.2011.01.004

Rao, K. M. M., & Rao, K. M. (2007). Extraction and tensile properties of natural fibers: Vakka,

date and bamboo. Composite Structures, 77(3), 288–295.

https://doi.org/10.1016/j.compstruct.2005.07.023

Rocky, B. P., & Thompson, A. J. (2018a). Production of natural bamboo fibers-1: experimental

approaches to different processes and analyses. The Journal of The Textile Institute,

109(10), 1381–1391. https://doi.org/10.1080/00405000.2018.1482639

Rocky, B. P., & Thompson, A. J. (2018b). Production of natural bamboo fibers-1: experimental

approaches to different processes and analyses. The Journal of The Textile Institute,

109(10), 1381–1391. https://doi.org/10.1080/00405000.2018.1482639

Rocky, B. P., & Thompson, A. J. (2018c). Production of Natural Bamboo Fibers-3: SEM and

EDX Analyses of Structures and Properties. AATCC Journal of Research, 5(6), 27–35.

https://doi.org/10.14504/ajr.5.6.4

Sanjay, M. R., Madhu, P., Jawaid, M., Senthamaraikannan, P., Senthil, S., & Pradeep, S. (2018).

Characterization and properties of natural fiber polymer composites: A comprehensive

review. Journal of Cleaner Production, 172, 566–581.

https://doi.org/10.1016/j.jclepro.2017.10.101

Sharma, B., Gatóo, A., & Ramage, M. H. (2015). Effect of processing methods on the

mechanical properties of engineered bamboo. Construction and Building Materials, 83,

95–101. https://doi.org/10.1016/j.conbuildmat.2015.02.048

42

Steffen, D., Marin, A. W., & Müggler, I. R. (2013). Bamboo: A holistic approach to a renewable

fibre for textile design. 10th European Academy of Design Conference - Crafting the

Future, 1–14.

Tokoro, R., Vu, D. M., Okubo, K., Tanaka, T., Fujii, T., & Fujiura, T. (2008). How to improve

mechanical properties of polylactic acid with bamboo fibers. Journal of Materials

Science, 43(2), 775–787. https://doi.org/10.1007/s10853-007-1994-y

Tran, D. T., Nguyen, D. M., Thuc, C. N. H., & Dang, T. T. (2013). Effect of coupling agents on

the properties of bamboo fiber-reinforced unsaturated polyester resin composites.

Composite Interfaces, 20(5), 343–353.

Waite, M. (2009). Sustainable textiles: The role of bamboo and a comparison of bamboo textile

properties. Journal of Textile and Apparel, Technology and Management, 6(2), 1–21.

Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-

77956939343&partnerID=40&md5=83af74431d5750ecc0e46b016dc62406


properties (Part II). Journal of Textile and Apparel, Technology and Management, 6(3),

1–22. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-


Wang, F., Shao, J., Keer, L. M., Li, L., & Zhang, J. (2015). The effect of elementary fibre

variability on bamboo fibre strength. Materials and Design, 75, 136–142.


Wang, H., Tian, G., Li, W., Ren, D., Zhang, X., & Yu, Y. (2015). Sensitivity of bamboo fiber

longitudinal tensile properties to moisture content variation under the fiber saturation

point. Journal of Wood Science, 61(3), 262–269. https://doi.org/10.1007/s10086-015-

1466-y

Witayakran, S., Haruthaithanasan, M., Agthong, P., & Thinnapatanukul, T. (2013). Green

Production of Natural Bamboo fibers for Textiles. In 2013 International Textiles and

Costume Congress (Vol. 28-29 Octo, pp. 1–6).

Xi, L., Qin, D., An, X., & Wang, G. (2013). Resistance of natural bamboo fiber to

microorganisms, and factors that may affect such resistance. BioResources, 8(4), 6501–

6509.

Xu, G., Wang, L., Liu, J., & Wu, J. (2013). FTIR and XPS analysis of the changes in bamboo

chemical structure decayed by white-rot and brown-rot fungi. Applied Surface Science,

280, 799–805. https://doi.org/10.1016/j.apsusc.2013.05.065

Yang, S., & Gordon, S. (2016). A study on cotton fibre elongation measurement. In 33rd

International Cotton Conference Bremen, March 16 - 18, 2016 (pp. 1–15).

Yu, Y., Wang, H., & Lu, F. (2014). Bamboo fibers for composite applications: a mechanical and

morphological investigation. Journal of Materials Science, 49(15), 2559–2566.

43

https://doi.org/10.1007/s10853-013-7951-z

Yueping, W., Ge, W., Haitao, C., Genlin, T., Zheng, L., Feng, X. Q., … Xushan, G. (2010).

Structures of Bamboo Fiber for Textiles. Textile Research Journal, 80(4), 334–343.

https://doi.org/10.1177/0040517509337633

Zakikhani, P., Zahari, R., Sultan, M. T. H., & Majid, D. L. (2014). Extraction and preparation of

bamboo fibre-reinforced composites. Materials and Design, 63, 820–828.


----------------------۞-----------------------

44

CHAPTER 3. CHARACTERIZATION OF THE CRYSTALLOGRAPHIC PROPERTIES

OF BAMBOO PLANTS, NATURAL AND VISCOSE FIBERS BY X-RAY

DIFFRACTION METHOD

3.1 Abstract

A comprehensive crystallographic investigation was performed by using X-ray (from cobalt

source) diffraction (XRD) technique on different bamboo species, natural bamboo fibers (NBFs),

commercial bamboo viscose products and different conventional fibers. Crystallinity indexes

(CI) were estimated as 61-67% of bamboo plants, 69-73% of NBFs, 35-40% of bamboo viscose

and 77-80% of cotton fibers in this study. Results suggests that CI gradually increased during the

delignification process to create NBFs up to a certain point and then decreased with further

processes. Knowing this behavior informs decisions of the appropriate chemicals or enzymes for

further modification processes and continuing to maintain expected strength of the fiber.

Therefore, delignifying raw bamboo increased the strength of the fibers until the maximum CI

was achieved but further extraction of lignin reduced the strength of the NBF resulting in a

higher number of fiber breakage and short fibers. Red Margin was found to have lower CI that

hinted at easier NBF extraction. With overall crystallite size of 35-39 Å, four crystalline peaks

were detected in all bamboo and NBF specimens as (101), (101̅), (002) and (040) at 17.0-

18.6°, 18.5-19.4°, ~25.5°, and ~40.5° respectively. Moreover, this study provides a list of lattice

planes, interplanar spacings, reflection angles, and crystallite dimensions of the four targeted

bamboo and NBF materials.

45

KEYWORDS: Bamboo Crystallinity; Crystallinity index; Crystal size; X-ray diffraction; Fiber

lattice indices; Crystallinity of Fibers.

3.2 Introduction

Recent research interest in bamboo for fiber production is leading to investigations for

identifying its structures and characteristics that can promote fiber extraction and modification

processes. The major three components of bamboo are cellulose, hemicellulose, and lignin.

Cellulose and hemicellulose are naturally-occurring polymers, namely polysaccharides, of 1,4--

D glucopyranose (glucose) monomers containing crystalline (orderly) and amorphous

(disorderly) regions (Mohamed & Hassabo, 2015; Odian, 2004; Oudiani, Chaabouni, Msahli, &

Sakli, 2011). The presence of crystallinity in polymers determines properties, such as strength,

elasticity, toughness, brittleness, stiffness, rigidity, chemical resistance, absorption, melting

temperature, density, optical and dyeing property (Carraher, 2003; Chen, Yu, Zhang, & Lu,

2011; Hindeleh, 1980; Mohamed & Hassabo, 2015; Stana-Kleinschek, Ribitsch, Kreže, Sfiligoj-

Smole, & Peršin, 2003). Accordingly, knowing the degree of crystallinity or crystallinity index

(CI) of cellulose-based plants provide us with information about whether the material has the

potential for fiber application and how it can be modified for suitable uses.

The CI is a very important distinct property that determines the uniqueness of a polymer

or a fiber. It is a challenging and complex process to determine the CIs of cellulosic polymer

materials (Ju, Bowden, Brown, & Zhang, 2015; Park, Baker, Himmel, Parilla, & Johnson, 2010).

Most of the polymers have a certain degree of crystallinity; only a very few of them have a CI of

100%. The CI of polymers generally ranges from 10-80% (Carraher, 2003; Ju et al., 2015). The

CI of natural fibers were reported between 30-90% (Sanjay et al., 2018). Unlike amorphous

polymers, polymers with a certain CI have a definite melting point and glass transition

temperature, and they display clear X-ray diffraction patterns. The crystallinity can be modified

46

or changed through production processes or by treatments (Carraher, 2003; Odian, 2004). The

polymer structure or orientation and the intermolecular forces are two major factors responsible

for crystal formation in polymers. The greater the secondary attraction forces, the higher the

degree of ordering and therefore the crystallinity of a polymer (Carraher, 2003; Mohamed &

Hassabo, 2015; Odian, 2004).

There are several methods to consider when determining crystallinity of polymers such as

differential scanning calorimetry (DSC), X-ray diffraction (XRD), solid-state nuclear magnetic

resonance NMR, infrared (IR) spectroscopy, Raman spectroscopy, density measurement, and

heat fusion (Carraher, 2003; Ju et al., 2015; Junior, Teixeira, & Tonoli, 2018; Moly, Radusch,

Androsh, Bhagawan, & Thomas, 2005; Odian, 2004; Park et al., 2010; Pe´rez & Mazeau, 2005;

Wada, Heux, & Sugiyama, 2004). Though DSC is most common, XRD, a non-destructive

method, has recently been found to be the most direct, widely used and easier method to

determine CI and crystal size of polymers. But it requires researchers to separate crystalline and

amorphous phases from the diffracted graph in order to use it (Carraher, 2003; French & Cintrón,

2013; Hindeleh, 1980; Moly et al., 2005; Odian, 2004; Park et al., 2010).

The main purpose of this crystallographic study was to determine the degree of

crystallinity (CI) and the crystallite sizes of four abundantly grown bamboo plants by X-ray

diffraction (XRD) technique with Co K as an X-ray source instead of the routinely used Cu

K. Comparisons of the crystallographic properties such as crystal sizes, CIs, reflection planes,

diffraction angles and interplanar distances among different bamboo plants, NBFs, cotton, and

different commercial viscose fibers measured. This study also aimed to investigate Segal (Segal,

Creely, Martin, & Conrad, 1959), a frequently used method and deconvolution (Rotaru et al.,

2018), a more accurate but complex method for determining the CIs.

47

3.3 Methodology

3.3.1 Materials and machines

This study was conducted on four bamboo species of 2-4-year-old plants that are abundantly

available: Red Margin (Phyllostachys rubromarginata), Moso (Phyllostachys edulis/ pubescens),

Giant Gray (Phyllostachys nigra henon), and Bissetii (Phyllostachys Bissetii) were collected

from Lewis Bamboo, Inc., Alabama, USA. Sodium hydroxide (NaOH) beads, sodium

bicarbonate (NaHCO3), sodium silicate (Na2SiO3), sodium triphosphate (85% Na5P3O10), and

sodium sulfite (Na2SO3) were purchased from Sigma-Aldrich, USA. Hydrogen peroxide/H2O2

(30% w/w) was provided by VWR International, LLC, USA. A scouring agent (Consoscour

GSRM), bleaching agent (Consobleach CIL), and penetrating agent (Consamine JDA) were

purchased from Consos, Inc. USA and fabric softener was collected from a local Publix Super

Market, Inc., USA.

The following machines and equipment were employed: Milling machine (Rolling Mill

Division, Stanat Manufacturing Co. Inc, NY.), Launderometer (AATCC Launder-Ometer, Atlas

material testing Technology LLC), Dryer (Model 18, GCA corporation), Conditioning cabinet

(Associated Environmental Chamber), and X-ray diffractometer (D8 Discover, Bruker AXS)

with Vantec 500 2D detector,

3.3.2 Extraction of Natural Bamboo Fibers (NBFs)

The details of the NBF extraction processes were documented in Part-1. A brief description is

included here. Raw fresh/green bamboo culms were subjected to splitting, repeated pressing in a

milling machine, steel-brushing, and removing short non-fibrous particles by washing and drying

successively. Then samples were soaked in a 6 g/L NaOH solution with a material-to-liquor ratio

(M:L) of 1:10-20 at room temperature for 3-5 days. These soaked samples were washed, combed

with a steel brush and dried in a dryer for 1 hour at 100-120 °C followed by conditioning in a

48

conditioning chamber. This yielded the initial fibers (R-1, B-1, G-1, and R-1) from each bamboo

specimen, such as B-1 from Bissetii, G-1 Giant Gray, M-1 from Moso, and R-1 from Red

Margin bamboo.

The NBF R-9 was produced by using a high concentration solution of NaOH (20 g/L)

with a liquor ratio (LR) of 1:10-20 at 90 °C for 3 hours followed by washing and drying. Initial

fibers (R-1, and B-1) were treated with 10-20 g/L NaOH, 5-8 g/L Na5P3O10, and 8-10 g/L

Na2SO3 solution (LR = 1:15) at 90 °C for 2.5 hours followed by washing and drying to yield R-

16 and B-16. Similarly, B-1, G-1, M-1 and R-1 were treated with a 5-6 g/L NaOH, 10-20 g/L

Na5P3O10, 10-15 g/L Na2SO3, and 10-20 mL/L Na2SiO3 solution (LR = 1:15) at 90 °C for 6 h to

yield G-21, M-21 and R-21. B-1, G-1, M-1 and R-1 were also treated with 5 g/L NaOH, 10 g/L

Na5P3O10, 10 g/L Na2SO3, 10 mL/L Na2SiO3, 4 mL/L scouring agent, 4 mL/L bleaching agent,

20 mL/L fabric softener, and 5 mL/L penetrating agent solution (LR = 1:15) at 90 °C for 8 h to

yield B-22, G-22 and M-22. Another treatment of B-22, G-22 and M-22 with a 3 g/L NaOH, 6

g/L NaHCO3, 6 mL/L H2O2, 3 mL/L scouring agent, 3 mL/L bleaching agent, and 4 mL/L

penetrating agent solution (LR = 1:15-20) at 90 °C for 6-7 h yielded B-23, G-23 and M-23.

Further treatment of B-23, G-23, M-23 and R-23 with a 2 g/L NaOH, 6 g/L NaHCO3, and 4-6

mL/L H2O2 solution (LR = 1:15-40) at 90 °C for 60-90 minutes yielded B-25, G-25, M-25 and

R-25. The NBF R-27 was extracted by treating R-1 with a solution of 5 g/L NaOH, 10 g/L

NaHCO3, 10 g/L Na5P3O10, and 10 mL/L Na2SiO3 (LR = 1:15) at 90 °C for 8 h, then final

treatments of R-23 and R-25 were applied respectively. The details of recipes and routes are

mentioned in part 1. All the heat treatments were executed in a Launderometer.

49

3.3.3 Crystallographic Analyses by XRD

Sample Preparation and Conditions

Raw bamboo specimens: A knife and a low-speed abrasive precision cutting machine with a

rotary blade were used to make thin bamboo slices with dimensions of 2~3 cm long ×

1~2 cm wide × 1~3 mm. The exodermis and endodermis were removed to provide smooth

surfaces where the distribution of fibers was uniform as shown in Figure 7. No polishing or

metal-coating was applied to strip samples. Both sides of the bamboo strips were used for

scanning in all analysis. Natural bamboo fiber (NBF) samples were prepared by gold-coating in

an ion sputter coater. All the specimens were stored in a desiccator before using in a

spectrometer.

Figure 7: Bamboo sliced strips prepared for X-ray diffractometry in Bruker AXS.

In XRD, for the raw bamboo samples, the bamboo culms were dried and cut into small

square or rectangular thin strips as mentioned above. Different fabrics were directly used as a

single-layered or a double-layered specimen to scan in the diffractometer. The NBFs and other

fiber samples were cut into very small pieces, ground in a grinder into the powder form as much

as possible, and collected by using a multiple layered micro-sieve containing 80, 120, 170, and

230 phosphor-bronzed meshes. The ground fibers were placed in a specimen holder in the

diffractometer. The X-ray from cobalt source (Co K1 and K2 x-rays) with wavelengths of

50

1.7890 Å was run at a beam voltage of 40 kV and a filament current of 35 mA using wide-angle

X-ray diffraction (WAXD) method. The XRD data collection time was 4-15 minutes with 360-

degree rotation around Z-axis between 4-96° scanning angle (2θ).

Determination of Crystallinity Index (CI)

The CIs of the four bamboo plants were determined by separating the crystalline and amorphous

phases from the diffracted graph (Figure 8). It should be noted that copper is mostly used as an

X-ray source for fibers or polymers that has a lower wavelength (1.5406 Å). Therefore, it is

expected that cobalt X-ray source with a higher wavelength would give bigger reflection angle in

the diffraction patterns. There are two methods that are reported to determine the degree of

crystallinity or crystallinity index (CI): 1) Segal method by using the height of the crystalline and

amorphous peaks, and 2) deconvolution method by calculating the area under crystalline and

amorphous peaks. The Segal method is direct and makes it easier to find CI by using equation

(2).

𝐶𝐼 =𝐼002 − 𝐼𝑎𝑚

𝐼002× 100% … … … … . (2)

Where 𝐼002 = the maximum intensity of the peak on 002 plane, and Iam = the minimum height

of the amorphous phases of the diffracted beam between (002) and (101) planes (Afrin,

Kanwar, Wang, & Tsuzuki, 2014; French & Cintrón, 2013; Ju et al., 2015; Lionetto, Del Sole,

Cannoletta, Vasapollo, & Maffezzoli, 2012; Morais et al., 2013; Nam, French, Condon, &

Concha, 2016; Oudiani et al., 2011; Park et al., 2010; Rambo & Ferreira, 2015; Segal et al.,

1959). The values of 𝐼002 and Iam were measured as shown in Figure 8. The deconvolution

51

Figure 8. Deconvolution method applied to the X-ray (from Cobalt source, Co K) diffraction

pattern of natural bamboo fiber (NBF) M-25 from Moso bamboo sample by using FitPeak

processing.

method is reported as more accurate but requires complex work to fit the peaks to calculate areas

under crystalline and amorphous peaks with careful data processing. Both of these methods can

be used to compare values obtained from each technique. Equation (3) is used to estimate CI in

method 2.

𝐶𝐼 =𝐴𝑐𝑟

𝐴𝑐𝑟 + 𝐴𝑎𝑚× 100% = [1 −

𝑆𝑎𝑚

𝑆𝑐𝑟 + 𝑆𝑎𝑚] × 100% … … … . (3)

Here, 𝐴𝑐𝑟 = the integrated area of the crystalline phase/peak; 𝐴𝑎𝑚 = the integrated area of the

amorphous phase/peak; 𝑆𝑐𝑟 𝑎𝑛𝑑 𝑆𝑎𝑚 are the sum of the area of the crystalline peaks and

52

amorphous regions respectively (French & Cintrón, 2013; Junior et al., 2018; Malenab, Ngo, &

Promentilla, 2017; Park et al., 2010; Rambo & Ferreira, 2015; Rotaru et al., 2018; Segal et al.,

1959).

The Segal method was applied to the raw data and to the data after subtracting the

background. The deconvolution method was used in Origin Pro 2018 64 bit to the XRD data for

CIs estimation. In this method, crystalline and amorphous regions were separated by utilizing

maximum data fitting in the XRD spectrum as mentioned in the literature (Garvey, Parker, &

Simon, 2005; Ju et al., 2015; Junior et al., 2018; Malenab et al., 2017; Park et al., 2010; Polizzi,

Fagherazzi, Benedetti, Battagliarin, & Asano, 1990). Both Gaussian and Pseudo-Voigt 2

functions were applied to the XRD spectrograms and the best shape fitting function was chosen

using least square fitting. The XRD raw data were treated with the maximum number of

iterations to achieve the Coefficient of determination (COD), 𝑅2. The regression predictions

were achieved above 97% (>97%) fit with raw data in all the cases after creating a baseline by

subtracting the background as shown in Figure 8. The amorphous peak was assigned between

24-26° 2θ-angle as it fitted well within that range.

Determination of Crystallite Size (𝑫𝟎𝟎𝟐)

If D002 = grain diameter or crystallite size using diffraction pattern on 002 lattice plane, β002

=

the true peak broadening at full-width half maximum (FWHM) in radian of the peak on the (002)

plane where instrumental broadening may need to be considered, θ = Bragg’s angle or the angle

of the diffracted beam, and λ = wavelength of the X-ray source, then equation (4) can be used to

determine the crystallite size of a polymer.

𝐷002 =𝑘𝜆

𝛽002 𝑐𝑜𝑠𝜃… … … … (4)

53

Where k is a dimensionless number with a value of around unity, also called Scherrer constant. It

depends on crystal shape, FWHM, and crystal orientation. The value of 𝑘 generally varies from

0.8 to 1.0 for polymer and cellulosic materials (Afrin et al., 2014; French & Cintrón, 2013; Hui

& Li, 2016; Kılınç et al., 2018; Langford & Wilson, 1978; Lionetto et al., 2012; Nam et al.,

2016; Tan, Hamid, & Lai, 2015; Yueping et al., 2010). The instrumental broadening was zero in

this experiment. In this study, the values of k = 1 and λ = 1.7890 Å (Co Kα1) were taken for

calculations.

3.4 Results and Discussion

3.5 Crystallographic Analyses

3.5.1 Crystallinity Indexes (CIs), Diffraction Angles, and Lattice Planes

The CIs were estimated as 63-66% and 70-72% in the Segal method and, 61-67% and 69-73% in

deconvolution method for all four bamboo species and NBFs respectively (Table 10). In 4-8

different XRD scans on different samples of a certain species and NBFs, the CIs were very close

providing <2% standard deviations. This was also the same for the two methods. This provides

us with the conclusion that the selected four bamboo plants and NBFs had the CIs between 63-

67% and 69-73% which were consistent with both methods (Table 10). The reported CIs for

bamboo and its natural fiber were reported as 52-89% (Afrin et al., 2014; He, Cui, & Wang,

2008; Junior et al., 2018; Y. Xu, Lu, & Tang, 2007; Yueping et al., 2010). Since a large fraction

of other compounds are grown along with fibers in the bamboo plant and the crystalline

orientation is not freely developed, Yueping et al. (2010) stated that the CI of bamboo fiber

(52.54%) was lower than cotton, ramie, and flax which is in good agreement with this study

(Yueping et al., 2010). Moreover, a higher content of non-crystal lignin compounds reduces the

crystallinity of the cellulosic materials (Wang, Cui, & Zhang, 2012). Summarized in Table 10, is

the investigation of the crystallinity of raw and mildly bleached 100% cotton fiber and fabric

54

(76-79%), several bamboo viscose products (35-40%), conventional rayon (40%),

cotton/bamboo viscose blend (63-66%) and polyester (62-65%). This comparison revealed that

intact bamboo and NBFs have a lower CI than cotton but a higher CI than all kinds of viscose

products. It was also noticed that bamboo viscose and conventional rayon showed similar XRD

patterns with close CI values. Understandably, specimen-BB showed a higher CI than bamboo

viscose but a lower value than cotton as it was a blend of cotton and viscose (Table 10).

Table 10

Estimated crystallinity indexes (CIs) of different bamboo species, NBFs, bamboo viscose

products, and conventional fibers by using Segal and Deconvolution methods on X-ray

diffraction data

Sample Description Segal Method,

CI% Deconvolution Method, CI%

Bissetii Raw Bamboo 66.4 66.67

B-25 NBF: 33 Ne/17.9 Tex 69.54 71.24

Giant Gray Raw Bamboo 62.56 63.51

G-25 NBF: 61 Ne/9.7 Tex 72.2 69.06

Moso Raw Bamboo 62.97 64.3

M-25 NBF: 33 Ne/23.6 Tex 70.79 69.92

Red Margin Raw Bamboo 62.65 60.8

R-25 NBF: 43 Ne/13.7 Tex 72.09 73.2

RCF 100% Raw cotton fiber 78.9 76.51

BCF Mildly bleached cotton (100%) fiber 77.89 75.88

UC Untreated (sized) 100% cotton fabric 78.02 79.16

BV 100% Bamboo viscose 38.67 35.72

Yala Commercial 100% bamboo viscose apparel 40.41 35.33

CR Conventional 100% rayon fabric 39.79 40.15

Piko Commercial (95% bamboo viscose, 5%

spandex) apparel 40 37.91

BB Commercial (70% bamboo viscose, 30%

cotton) apparel 65.73 62.87

Polyester Polyester fiber 61.73 65.47

Three peaks were clearly found in the diffraction graphs of all bamboo and NBF

specimens at 18-20°, ~25.5° and ~40.5° angles as shown in Figure 8 and Figure 9. In literature,

55

the reflection on (101), (101̅), (002)and (040) lattice planes were reported for cellulose-based

materials (Chen et al., 2011; Ju et al., 2015; Malenab et al., 2017; Nam et al., 2016; Oudiani et

al., 2011; Polizzi et al., 1990). Through peak fitting analysis, it was found that the peak at 18-20°

was a combined peak of two peaks of (101), (101̅) planes at around 17.0-18.6° and 18.5-19.4°.

These two peaks were overlapped in most of the scans and they were treated as a single peak to

Figure 9. X-ray diffraction patterns of four bamboo species showing different peaks for

determining the crystallinity indexes and the crystal sizes.

56

Table 11

Size of the crystallites, reflection planes, diffraction angles, and interplanar distances of four

bamboo species and natural bamboo fibers (NBFs) from X-ray (Co K source) diffraction

technique

estimate the crystallinity index. Thus, a thorough analysis of data in this study showed that the

lattice planes (101), (101̅), (002) and (040) were detected at 17.0-18.6°, 18.5-19.4°, ~25.5° and

Sample Lattice plane

(hkl) Diffraction angle,

2θ (°) Interplanar distance (Å)

Crystallite Dimension (Å)

Bissetii

101 17.6 5.85 30.87 101̅ 19.2 5.37 30.49 002 25.6 4.04 36.50 040 40.6 2.58 51.79

B-25 (NFB from Bissetii)

101 17.7 5.80 29.11 101̅ 19.0 5.41 29.19 002 25.6 4.04 37.22 040 40.5 2.58 52.64

Giant Gray

101 17.1 6.01 27.86 101̅ 18.8 5.49 28.00 002 25.7 4.03 34.86 040 40.5 2.58 51.78

G-25 (NFB from Giant gray)

101 17.7 5.81 29.42 101̅ 18.6 5.55 30.69 002 25.7 4.02 36.88 040 40.0 2.61 43.12

Moso

101 17.6 5.84 29.31 101̅ 18.5 5.56 29.73 002 25.5 4.05 34.92 040 40.5 2.59 61.03

M-25 (NFB from Moso)

101 17.5 5.90 32.06 101̅ 19.0 5.41 32.13 002 25.5 4.05 38.64 040 40.5 2.59 56.90

Red Margin

101 17.0 6.06 30.13 101̅ 19.2 5.37 29.37 002 25.7 4.03 37.28 040 40.6 2.58 33.94

R-25 (NFB from Red Margin)

101 18.6 5.53 32.87 101̅ 19.4 5.31 33.01 002 25.5 4.06 38.49 040 40.5 2.58 52.03

Cotton (Untreated 100% cotton fabric)

101 17.3 5.96 44.31 101̅ 19.1 5.38 52.77 002 26.4 3.92 69.72 040 021

39.6 2.64 107.87 24.4 4.24 90.40

57

~40.5° respectively (Table 11). However, the most intense crystalline peak was at ~25.5° on the

(002) lattice plane for all the samples. Most of the reported investigations also found such clear

peaks within different scanning angles (2θ) (Afrin et al., 2014; Lionetto et al., 2012; Yueping et

al., 2010). The peaks on planes (101), (101̅), (002) and (040) are reported at 14-15.5°, 16-17°,

21.7-23° and 34.0-35.1° respectively when Cu K X-ray source with a wavelength, 𝜆 =

1.5406 Å was used (Besbes, Alila, & Boufi, 2011; Chen et al., 2011; Ciolacu, Gorgieva, Tampu,

& Kokol, 2011; French & Cintrón, 2013; Garvey et al., 2005; Hindeleh, 1980; Hu & Hsieh,

1996; Junior et al., 2018; Lionetto et al., 2012; Malenab et al., 2017; Oudiani et al., 2011; Park et

al., 2010; Segal et al., 1959; Tan et al., 2015; Y. Xu et al., 2007; Yueping et al., 2010). So, by

using Bragg’s law, these peaks were expected at 16.3-18.1°, 18.7-19.9°, 25.4-27.0° and 40.5-

41.9° angles for Co K X-ray source with a wavelength, 𝜆 = 1.7890 Å which was observed in

this investigation.

Although the shape and the position of the amorphous regions of different samples were

slightly different, an overlapping of the peak on (101) and (101̅) planes and all other peaks with

their distribution were almost identical (Figure 9). It should be noted that similar patterns were

observed in the X-ray spectra of NBFs specimens (Figure 9, Figure 10). Presented in Figure 10,

the diffraction patterns of Bissetii, Giant Gray, Moso, Red margin, and their respective natural

fibers B-25, G-25, M-25, and R-25 respectively revealed that bamboo and its fibers produced

similar patterns. However, the amorphous area, the position and the height of peaks were

different that produced unequal CIs (Table 11). Though the peak (101) and (101̅) were clear and

in different positions, and a peak at 24.4° on (021) plane was identified in the diffraction pattern

of cotton, this was not the cases for bamboo and NBFs (Figure 10). It was also noticeable in the

diffraction spectra when plotted altogether that the intensity of the Bissetii plant sample,

58

Figure 10. Comparison of X-ray (from Co K source) diffraction patterns among four bamboo

species, natural bamboo fibers (NBFs) and cotton.

compared with its amorphous peak and the greatest CI (66-67%), was greater than the other three

plant samples (Figure 9). Similarly, the CIs were directly related to the intensity of the

corresponding diffraction patterns. A higher CI is indicative of increased brittleness of the fibers

in the plant (Carraher, 2003). This indicates that the Red Margin plant with the lowest CI (61-

63%) would be better for fiber production as it will promote a lower amount of fiber breakage

59

during mechanical and other processes. Such a result agrees with the finding in Part-1 that NBFs

extraction was easier from Red Margin than the other three species. A lower crystallinity may

also come from a younger-aged bamboo plant of the same species.

Figure 11. Change in crystallinity indexes as natural bamboo fibers (NBFs) were extracted into

finer forms or count (Ne) through different stages of processing.

It was noticed that almost in all cases of four bamboo species, crystallinity indexes were

decreased from raw bamboo to NBFs up to a certain stage of delignification in the production

process (Figure 11) which was observed in other studies as well (G. Xu, Wang, Liu, & Wu,

2013). But CIs increased from that point to the final production when fibers were in the finest

form from a sample. Probably, the first few steps of delignification caused the NBFs to become

more disordered but later steps reorganized as non-crystalline lignin and other components were

removed. Thus the CI of the final NBF from each of four bamboo species was the maximum.

60

However, though the range of the CIs of the raw bamboo from four species was 62-66%, the

range of the CIs of their final NBFs in this study was 68-72% (Figure 11).

3.5.2 Crystallite Dimensions and Interplanar Spacings

The size of the crystallites with respect to (002) plane were 36.50, 34.86, 34.92 and 37.28 Å for

the four species Red Margin, Moso, Giant Gray, and Bissetii respectively with very small

standard deviations (Table 11). The results were similar for multiple scans on different samples

from each species. The crystallite sizes were not too different when estimated from raw data or

from background-subtracted data. The sizes of the crystallites of NBFs were equivalent (37-39

Å). So, the techniques were consistent and suitable in multiple repeats to estimate the results.

Therefore, the estimated overall size of the crystals based on the most intense peak on (002)

lattice plane was within the range of 35-39 Å (3.5-3.9 nm) which is almost half of the crystal’s

size (69.72 Å) of experimented cotton fibers (Table 11). These results are supported by other

investigations as 36.5 Å for bamboo raw biomass (Afrin et al., 2014; Thomas et al., 2015).

In Table 11, the interplanar distances of the lattice structures of different crystals obtained

from different bamboo species and NBFs were 5.8-6.0 Å for (101) plane, 5.4-5.6 Å for (101̅)

plane, ~4.0 Å for (002) plane, and 2.6 Å for (040) planes. These value of the spacings were

similar to cotton fibers as observed in this study.

3.6 Conclusions

There are over 1500 fast-growing bamboo species in the world. However, only a few species of

bamboo have been studied for fiber applications and thus its properties. Only very few studies

have been dedicated to the characterization of bamboo and its fibers. Knowing different chemical

and structural properties would promote bamboo's benefits by matching it to different purposes,

especially the production of textiles and apparel by using natural bamboo fiber (NBF) which

could provide some special characteristics.

61

Though the crystallinity is one of the most important factors of fibers, it has not been

studied in terms of crystalline properties of different bamboo species in previous studies. This

investigation focused on four of the most common bamboo species and on extracted natural

bamboo fibers (NBFs) from the plants to determine crystallinity indexes, their respective

crystallite sizes and other crystallographic analyses by X-ray diffraction (XRD) technique using

a Cobalt K (Co K) X-ray source. Four peaks were identified on (101), (101̅), (002) and (040)

lattice planes at 17.0-18.6°, 18.5-19.4°, 25.5°, and 40.5° respectively in all bamboo and NBF

samples where the peak on (002) corresponded to the most intense peak. Both Segal and

deconvolution methods confirmed that the approximate crystallinity indexes (CIs) were 63-67%

for the raw bamboo specimens of four species Red Margin, Moso, Giant Gray, and Bissetii, and

69-73% for NBFs from the plants. The CIs values of NBFs were lower than cotton fibers which

may indicate lower strength of NBF fibers than cotton. Also, a lower CI is related to softer feel

and perceived comfort in the clothing products of the fiber. The sizes of the crystallites as 35-39

Å (3.5-3.9 nm) were almost the same for all four bamboo plants and NBFs considering the most

intense peak only. The crystallographic information of bamboo and NBFs about lattice planes,

interplanar spacings, reflection angles, and crystallite dimensions are also reported. The results

and observations of this study would be useful to advance crystallographic knowledge on

bamboo plants and to guide fiber production and application from certain species.

3.7 References



1299. https://doi.org/10.1080/00405000.2014.889872

Besbes, I., Alila, S., & Boufi, S. (2011). Nanofibrillated cellulose from TEMPO-oxidized

eucalyptus fibres: Effect of the carboxyl content. Carbohydrate Polymers, 84(3), 975–

983. https://doi.org/10.1016/j.carbpol.2010.12.052

62

Carraher, C. E. (2003). Polymer Chemistry. New York: Marcel Dekker, Inc.

https://doi.org/10.1039/c8py01554f

Chen, X., Yu, J., Zhang, Z., & Lu, C. (2011). Study on structure and thermal stability properties

of cellulose fibers from rice straw. Carbohydrate Polymers, 85(1), 245–250.

https://doi.org/10.1016/j.carbpol.2011.02.022

Ciolacu, D., Gorgieva, S., Tampu, D., & Kokol, V. (2011). Enzymatic hydrolysis of different

allomorphic forms of microcrystalline cellulose. Cellulose, 18(6), 1527–1541.

https://doi.org/10.1007/s10570-011-9601-4

French, A. D., & Cintrón, M. S. (2013). Cellulose polymorphy, crystallite size, and the Segal

Crystallinity Index. Cellulose, 20(1), 583–588. https://doi.org/10.1007/s10570-012-9833-

y

Garvey, C. J., Parker, I. H., & Simon, G. P. (2005). On the interpretation of X-ray diffraction

powder patterns in terms of the nanostructure of cellulose I fibres. Macromolecular

Chemistry and Physics. https://doi.org/10.1002/macp.200500008

He, J., Cui, S., & Wang, S. Y. (2008). Preparation and crystalline analysis of high-grade bamboo

dissolving pulp for cellulose acetate. Journal of Applied Polymer Science, 107(2), 1029–

1038. https://doi.org/10.1002/app.27061

Hindeleh, A. M. (1980). X-Ray Characterization of Viscose Rayon and the Significance of

Crystallinity on Tensile Properties. Textile Research Journal, 50(10), 581–589.

https://doi.org/10.1177/004051758005001001

Hu, X. P., & Hsieh, Y. Lo. (1996). Crystalline structure of developing cotton fibers. Journal of

Polymer Science, Part B: Polymer Physics, 34(8), 1451–1459.

Hui, B., & Li, J. (2016). Low-temperature synthesis of hierarchical flower-like hexagonal

molybdenum trioxide films on wood surfaces and their light-driven molecular responses.

Journal of Materials Science, 51(24), 10926–10934. https://doi.org/10.1007/s10853-016-

0304-y

Ju, X., Bowden, M., Brown, E. E., & Zhang, X. (2015). An improved X-ray diffraction method

for cellulose crystallinity measurement. Carbohydrate Polymers, 123, 476–481.


Junior, M. G., Teixeira, F. G., & Tonoli, G. H. D. (2018). Effect of the nano-fibrillation of

bamboo pulp on the thermal, structural, mechanical and physical properties of

nanocomposites based on starch/poly(vinyl alcohol) blend. Cellulose, 25(3), 1823–1849.

https://doi.org/10.1007/s10570-018-1691-9

Kılınç, A. Ç., Köktaş, S., Seki, Y., Atagür, M., Dalmış, R., Erdoğan, Ü. H., … Seydibeyoğlu, M.

Ö. (2018). Extraction and investigation of lightweight and porous natural fiber from

Conium maculatum as a potential reinforcement for composite materials in

transportation. Composites Part B: Engineering, 140(November 2017), 1–8.


63

Langford, J. I., & Wilson, A. J. C. (1978). Scherrer after sixty years: A survey and some new

results in the determination of crystallite size. Journal of Applied Crystallography, 11(2),

102–113. https://doi.org/10.1107/S0021889878012844

Lionetto, F., Del Sole, R., Cannoletta, D., Vasapollo, G., & Maffezzoli, A. (2012). Monitoring

wood degradation during weathering by cellulose crystallinity. Materials, 5(10), 1910–

1922. https://doi.org/10.3390/ma5101910

Malenab, R. A. J., Ngo, J. P. S., & Promentilla, M. A. B. (2017). Chemical treatment of waste

abaca for natural fiber-Reinforced geopolymer composite. Materials, 10(579), 1–19.

https://doi.org/10.3390/ma10060579

Mohamed, A. L., & Hassabo, A. G. (2015). Flame Retardant of Cellulosic Materials and Their

Composites. In P.M. Visakh & Y. Arao (Eds.), Flame Retardants (pp. 247–314).

Springer International Publishing Switzerland. https://doi.org/10.1007/978-3-319-03467-

6_10

Moly, K. A., Radusch, H. J., Androsh, R., Bhagawan, S. S., & Thomas, S. (2005).

Nonisothermal crystallisation, melting behavior and wide angle X-ray scattering

investigations on linear low density polyethylene (LLDPE)/ethylene vinyl acetate (EVA)

blends: Effects of compatibilisation and dynamic crosslinking. European Polymer

Journal, 41(6), 1410–1419. https://doi.org/10.1016/j.eurpolymj.2004.10.016

Morais, J. P. S., Rosa, M. D. F., De Souza Filho, M. D. S. M., Nascimento, L. D., Do

Nascimento, D. M., & Cassales, A. R. (2013). Extraction and characterization of

nanocellulose structures from raw cotton linter. Carbohydrate Polymers, 91(1), 229–235.


Nam, S., French, A. D., Condon, B. D., & Concha, M. (2016). Segal crystallinity index revisited

by the simulation of X-ray diffraction patterns of cotton cellulose Iβ and cellulose II.

Carbohydrate Polymers, 135, 1–9. https://doi.org/10.1016/j.carbpol.2015.08.035

Odian, G. (2004). Principles of Polymerization (4th editio). Hoboken, New Jersey: John Wiley &

Sons, Inc. https://doi.org/10.1017/CBO9780511813535

Oudiani, A. El, Chaabouni, Y., Msahli, S., & Sakli, F. (2011). Crystal transition from cellulose I

to cellulose II in NaOH treated Agave americana L. fibre. Carbohydrate Polymers, 86(3),

1221–1229. https://doi.org/10.1016/j.carbpol.2011.06.037

Park, S., Baker, J. O., Himmel, M. E., Parilla, P. A., & Johnson, D. K. (2010). Cellulose

crystallinity index: Measurement techniques and their impact on interpreting cellulase

performance. Biotechnology for Biofuels, 3(10), 1–10. https://doi.org/10.1186/1754-

6834-3-10

Pe´rez, S., & Mazeau, K. (2005). Conformations, Structures, and Morphologies of Celluloses. In

S. Dumitriu (Ed.), Polysaccharides: Structural Diversity and Functional Versatility (pp.

41–68). Marcel Dekker, Inc., New York. https://doi.org/10.1201/9781420030822.ch2

64

Polizzi, S., Fagherazzi, G., Benedetti, A., Battagliarin, M., & Asano, T. (1990). A fitting method

for the determination of crystallinity by means of X-ray diffraction. Journal of Applied

Crystallography, 23(5), 359–365. https://doi.org/10.1107/S0021889890004939

Rambo, M. K. D., & Ferreira, M. M. C. (2015). Determination of cellulose crystallinity of

banana residues using near infrared spectroscopy and multivariate analysis. Journal of the

Brazilian Chemical Society, 26(7), 1491–1499. https://doi.org/10.5935/0103-

5053.20150118

Rotaru, R., Savin, M., Tudorachi, N., Peptu, C., Samoila, P., Sacarescu, L., & Harabagiu, V.

(2018). Ferromagnetic iron oxide-cellulose nanocomposites prepared by ultrasonication.

Polymer Chemistry, 9(7), 860–868. https://doi.org/10.1039/c7py01587a





Segal, L., Creely, J. J., Martin, A. E., & Conrad, C. M. (1959). An Empirical Method for

Estimating the Degree of Crystallinity of Native Cellulose Using the X-Ray

Diffractometer. Textile Research Journal, 29(10), 786–794.

https://doi.org/10.1177/004051755902901003

Stana-Kleinschek, K., Ribitsch, V., Kreže, T., Sfiligoj-Smole, M., & Peršin, Z. (2003).

Correlation of regenerated cellulose fibres morphology and surface free energy

components. Lenzinger Berichte, 82, 83–95. Retrieved from

https://www.lenzing.com/fileadmin/template/pdf/konzern/lenzinger_berichte/ausgabe_82

_2003/LB_2003_Stana_14_ev.pdf

Tan, X. Y., Hamid, S. B. A., & Lai, C. W. (2015). Preparation of high crystallinity cellulose

nanocrystals (CNCs) by ionic liquid solvolysis. Biomass and Bioenergy, 81, 584–591.

https://doi.org/10.1016/j.biombioe.2015.08.016

Thomas, L. H., Forsyth, V. T., Martel, A., Grillo, I., Altaner, C. M., & Jarvis, M. C. (2015).

Diffraction evidence for the structure of cellulose microfibrils in bamboo, a model for

grass and cereal celluloses. BMC Plant Biology, 15(1), 1–7.

https://doi.org/10.1186/s12870-015-0538-x

Wada, M., Heux, L., & Sugiyama, J. (2004). Polymorphism of cellulose I family:

Reinvestigation of cellulose IVl. Biomacromolecules, 5(4), 1385–1391.

https://doi.org/10.1021/bm0345357

Wang, X., Cui, X., & Zhang, L. (2012). Preparation and Characterization of Lignin-containing

Nanofibrillar Cellulose. Procedia Environmental Sciences, 16, 125–130.

https://doi.org/10.1016/j.proenv.2012.10.017



65


Xu, Y., Lu, Z., & Tang, R. (2007). Structure and thermal properties of bamboo viscose, Tencel

and conventional viscose fiber. Journal of Thermal Analysis and Calorimetry, 89(1),

197–201. https://doi.org/10.1007/s10973-005-7539-1



https://doi.org/10.1177/0040517509337633

----------------------۞-----------------------

66

CHAPTER 4. ANALYSES OF THE CHEMICAL COMPOSITIONS AND STRUCTURES

OF FOUR BAMBOO SPECIES AND THEIR NATURAL FIBERS BY INFRARED,

LASER AND X-RAY SPECTROSCOPIES

Abstract

Four bamboo species, natural bamboo fibers (NBF) from each species, commercial bamboo

viscose, and other conventional fibers were investigated in this study to determine and compare

elemental compositions, chemical bonds and behaviors. Elemental analyses with energy-

dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were

executed to identify elemental compositions in terms of atomic and weight/mass concentration,

O/C ratios of raw bamboo (0.26-0.42) and NBFs (0.44-0.70), binding energies, and components

of C 1s and O 1s peaks and corresponding chemical bonds: C-C, C-H, C-O, C=O, O-C-O, and

O-C=O. It was revealed that the O/C ratio increased with the fineness of NBFs which is an

indication of higher moisture regain or content. Since some chemical groups are not detected by

Fourier Transform Infra-Red (FTIR) spectroscopy and others are not detected by Raman

spectroscopy (RS), the importance of an investigation using both methods for identifying

chemical groups, bonds, and characteristics was verified in this study. FTIR with Attenuated

Total Reflectance (ATR) and Raman spectroscopies were employed to make a broad list of

identified characteristic peaks and their chemicals information of different bamboo species,

NBFs, cotton, and regenerated cellulosic fibers. The investigation discovered that NBFs may

possess most of the chemical groups and behaviors from the bamboo plants from which they

were extracted, and thus the properties. It was observed that bamboo viscose had similar bands to

regular viscose rayon, and many bands found in raw bamboo and NBFs spectra were not present

67

in the bamboo viscose. Results also revealed that bamboo and its NBF had some unique peaks

that were not detected in cotton, rayon of bamboo viscose spectra.

KEYWORDS: EDS; XPS; Fiber chemistry; FTIR; Raman spectroscopy; NBF compositions;

Bamboo properties.

4.1 Introduction

Bamboo is a highly studied plant, especially in investigations on manufacturing fibers for

textiles, fiber-reinforced composite materials, and other applications of the fiber. The major

constituents of bamboo biomass are cellulose (45-55%), hemicellulose (15-25%), lignin (15-

30%), pectin (0.5-1.5%) and other organic and inorganic compounds (Liu, Wang, Cheng, Qian,

& Yu, 2011; Nayak & Mishra, 2016; Rocky & Thompson, 2018; Tolessa, Woldeyes, & Feleke,

2017). Knowing chemical compositions and functional groups, different properties of the

bamboo plant and its fibers can be identified. Moreover, such information can help with selecting

proper chemicals or enzymes for fiber extraction by removing non-fibrous components and

enhancing existing properties of the extracted fibers (Fu et al., 2012; Thumsorn, Srisawat, On, &

Hamada, 2014; Xu, Wang, Liu, & Wu, 2013).

X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy

(EDS) are tools that are used frequently for quantification of elemental surface compositions

(Belgacem, Czeremuszkin, Sapieha, & Gandini, 1995; Herzele, van Herwijnen, Edler, Gindl-

Altmutter, & Konnerth, 2018; Johansson et al., 2005; Kılınç et al., 2018; Kyropoulou, 2013;

Migneault, Koubaa, Perré, & Riedl, 2015; Ouyang, Huang, & Cao, 2014; Popescu, Tibirna, &

Vasile, 2009; Truss, Wood, & Rasch, 2016; Wang et al., 2018; Zafeiropoulos, Vickers, Baillie,

& Watts, 2003). EDS, generally performed in a scanning electron microscope (SEM), has some

limitations on elemental quantification and is less precise for organic materials. EDS has proven

to be a tool capable of estimating some primary information about elemental composition of an

68

organic material (Hui & Li, 2016; Kyropoulou, 2013; Li, Bi, Song, Qu, & Liu, 2019; Nasser,

Mansour, Salem, Ali, & Aref, 2017; Ouyang et al., 2014). EDS, does not need special sample

preparation, though fibers are difficult to use in X-ray spectroscopy because of the sensitivity

issues and uneven/rough surface of the fiber that scatters reflected or transmitted rays out of the

detectors, it can still provide useful information (Pakdel, Cyr, Riedl, & Deng, 2008). Notably,

high sensitivity of XPS to a surface of a carbon-rich material can help to explore the atomic

nature and organic functional groups along with elemental bonding (Wang et al., 2018). An

example of a high carbon surface in which XPS is a highly used tool for characterizing is wood

pulp. XPS can be used to collect information about the surface of a specimen within 0.1—10 nm

(Kazayawoko, Balatinecz, & Sodhi, 1999; Truss et al., 2016). However, there is no standard or

systematic techniques to analyze fibers, polymers, or insulating fiber materials for such analysis

(Johansson et al., 2005). Determining of O/C atomic ratio and CC components are the two

methods used for XPS analysis of cellulose-based materials where cellulose, hemicellulose,

lignin, and other trace elements are the main components (Johansson et al., 2005; Kazayawoko et

al., 1999; Xu et al., 2013). Though there are some limitations, elemental analysis with EDS and

XPS can provide us with approximate elemental compositions, and the nature of Carbon-Carbon

and Carbon-Oxygen bonding (Belgacem et al., 1995; Kılınç et al., 2018; Migneault et al., 2015;

Pakdel et al., 2008; Popescu et al., 2009; Wang et al., 2018; Zhang, Zhang, & Lu, 2016; Zhou,

Guo, Yan, & Di, 2017).

The focuses of the EDS and XPS surveys were to identify and compare the elemental

composition, changes of O/C ratios during NBF extraction, binding energies, and components of

C 1s and O 1s along with their nature of bonding of four bamboo species and natural bamboo

fiber (NBF) from each of the plants.

69

As FTIR (Fourier Transform Infra-Red) and Raman spectroscopy (RS) have different

degrees of sensitivity to different functional groups, a combination of the tools can be useful for

chemical analysis. For example, FTIR has higher sensitivity towards hetero-functional groups

such as –OH, C-O and C-O-C but Raman spectroscopy is more sensitive in identifying homo-

functional groups such as C≡C, C=C, and C-C groups. For chemical groups and compositional

investigations, different cellulose-based materials such as wood pulps, biomass, fibers and

carbohydrate polymers were studied by using FTIR and Raman spectroscopies (Alves et al.,

2016; Cao, Shen, Lu, & Huang, 2006; Cho, 2007; Dai & Fan, 2011; Herzele et al., 2018; Hui &

Li, 2016; Kavkler & Demšar, 2011; Kılınç et al., 2018; Lee et al., 2015; Migneault et al., 2015;

Ouyang et al., 2014; Sepe, Bollino, Boccarusso, & Caputo, 2018; Zafeiropoulos et al., 2003;

Zhang et al., 2016). For convenience, FTIR, sometimes with an ATR (Attenuated Total

Reflectance) accessory, is extensively used for characterizing different natural or cellulose-based

fibers to identify chemical groups and nature of bonding (Carrillo, Colom, Suñol, & Saurina,

2004; Comnea-Stancu, Wieland, Ramer, Schwaighofer, & Lendl, 2017; Garside & Wyeth, 2016;

Lee et al., 2015; Migneault et al., 2015; Sanjay et al., 2018; Zhou et al., 2017).

Raman spectroscopy, is a non-destructive technique requiring simple or no sample

preparation and a very small sample can be used to collect information of micro- and macro-

levels (Cho, 2007; Kavkler & Demšar, 2011). Since natural fibers are long-chain polymers of

low dipole moments and FTIR is less sensitive to such materials, Raman spectroscopy can

produce a higher number of peaks in the spectra to exhibit more chemical information than

FTIR. FTIR is more commonly used for characterization of textiles materials than Raman

spectroscopy, even though Raman actually offers more advantages (Abbott, Batchelor, Smith, &

Moore, 2010; Alves et al., 2016; Cao et al., 2006; Cho, 2007; Kavkler & Demšar, 2011). Spectra

of the textile fibers and materials can be characterized into 3 regions: 150-610, 800-1750 and

70

2700-3350 cm-1 (Kavkler & Demšar, 2011; Schenzel & Fischer, 2001). Though the last two

regions are visible in both FTIR and Raman spectra, the first region is only detectable in Raman

spectra. However, Raman spectroscopy is also unable to detect some functional groups, such as

OH bond stretch of water. Therefore, an investigation with both spectroscopies can be regarded

as better than a single-tool observation. The only studies reporting the use of these techniques for

characterizing bamboo and its fibers can be found in G. Xu et al. (2013) and Yueping et al.

(2010).

The major purposes of the study were to identify chemical groups, bonds, behaviors and

other properties of different bamboo species and natural bamboo fibers (NBFs) by using FTIR

and Raman spectroscopies. Targets of the investigation also included comparing IR and Raman

spectra of bamboo and NBFs specimens with cotton, regular rayon viscose, and bamboo viscose

fibers.

4.2 Methodology

4.2.1 Materials and machines

Four bamboo plants— Red Margin (Phyllostachys rubromarginata), Moso (Phyllostachys

edulis/ pubescens), Giant Gray (Phyllostachys nigra henon), and Bissetii (Phyllostachys Bissetii)

were used in this study. All the relevant information about materials and machines are mentioned

in Part-2. Additionally, the following instruments were used: Ion Sputter Coater (Leica, MCM-

200 Ion Sputter Coater), JEOL 7000 (JEOL JSM-7000F, FE-SEM/Field Emission Scanning

Electron Microscope) for SEM and EDS, X-ray photoelectron spectrometer (Kratos Axis 165)

for XPS, FTIR spectrometer (Jasco FT/IR-4100) with ATR (MiracleTM ATR, PIKE

Technologies, Inc.), and Raman Spectrometer (LabRam HR800, Horiba Jobin Yvon, Horiba

Scientific).

71

4.2.2 Extraction of Natural Bamboo Fibers (NBFs)

The primary samples B-1, G-1, M-1 and R-1 were produced from Bissetii, Giant Gray, Moso,

and Red Margin respectively by applying initial treatments as mentioned in Part-1. The

processing sequences of different NBF specimens were as follows—

R-9: recipe 0 recipe 1 (Table 12).

M-22: recipe 0 recipe 3 (Table 12).

B/G-23: recipe 0 recipe 3 recipe 2 (Table 12).

B/G/M/R-25: recipe 0 recipe 3 recipe 2 recipe 5 (Table 12).

R-27: recipe 0 recipe 4 recipe 2 recipe 5 (Table 12).

The final sample of each set was subjected to neutralizing, washing, and drying.

Table 12

Recipes, chemicals and processing conditions for NBF extraction

Recipe NaOH (g/L)

NaHCO₃ (g/L)

H₂O₂ (mL/L)

Other chemicals M : L Temperature X

Time

0

6

- 1 : 1020 RT x 35 days

1 20 - - -

90 °C X 3 h

2 3 6 6

3 mL/L scouring agent (Consoscour GSRM), 3 mL/L bleaching agent

(Consobleach CIL), and 4 mL/L

penetrating agent (Consamine JDA)

1 : 1520 90 °C X 67 h

3 5 - -

10 g/L Na5P3O10, 10 g/L Na2SO3, 10 mL/L Na2SiO3, 20 mL/L fabric softener, 4 mL/L scouring agent, 4 mL/L bleaching agent,

and 5 mL/L penetrating agent 1 : 15 90 °C X 8 h

4 5 10 - 5 g/L Na5P3O10, 10 mL/L Na2SiO3

5 2 6 46 - 1 : 1540 90 °C X 11.5 h

4.2.3 Elemental analyses by XPS & EDS

Bamboo culms were split and undried strips were cut into small rectangular thin slices a low-

speed abrasive precision cutting machine and then the thin strips were dried before using in a

spectrometer. The details of the raw bamboo sample preparation are documented in Part-2. A

72

JEOL 7000 was used for EDS analysis of raw bamboo strips and gold-coated NBFs. Several

small spot areas and the bulk area were chosen for elemental spectra collection. The spectrum

and statistics from small spots were used to identify the presence of different elements and the

bulk areas were employed for compositional investigation. The EDS investigation was repeated

2-3 times for all samples.

Only raw bamboo strips were observed in XPS spectrometer. A monochromatic Al Kα

was used as the X-ray source (hν = 1486.7 eV) at a high vacuum of 10−9 to 10−8 torr. All XPS

spectra were collected between 0-1000 eV binding energy with a step size of 0.05-0.10 eV. The

CasaXPS software was used for XPS data analysis. CasaXPS software allowed the C 1s and O 1s

peaks and other components to be analyzed by curve fitting and deconvolution methods. The

O/C ratios of different spectra were calculated by using respective atomic percentage (At%), area

(A) and height (H) of C 1s and O 1s peaks from CasaXPS analysis.

O/C ratio =AOxygen

ACarbon × RSF=

HOxygen

HCarbon × RSF… … . . (1)

In equation (1), AOxygen and ACarbon are the areas, and ACarbon and HCarbon are the heights of O

1s and C 1s peaks respectively. The Relative Sensitivity Factor (RSF) of Oxygen was taken from

CasaXPS library which was considered 2.93 for Oxygen.

4.2.4 FTIR and Raman: Analyses of Chemical Groups

Raw bamboo strips were directly placed in spectrometers for spectra and data collection. Both

sides of each strip were scanned. The fiber samples were ground and collected through a micro-

sieve containing 4 layers of mesh size 80, 120, 170, and 230. All the fibers were scanned in fiber

and ground powder forms. In Raman spectroscopy, a single fiber was focused using a 100X

objective lens and proved to be suitable. Fiber-form specimens were challenging in ATR-FTIR

spectra collection.

73

For ATR-FTIR spectroscopy, spectra were collected for each sample at least 3 times (3-

5) within a range of 600—4000 cm-1 with a resolution of 2-4 cm-1 from 25-50 scans. Collected

spectra were normalized with respect to the most intense peak after baseline correction.

Raman spectrometer was used to scan from 100 cm-1 to 4000 cm-1 with 950 grating and a

laser of 785 nm wavelength (monochromatic light source) as it helps to avoid heating effects,

fluorescence, works well with the low sensitivity of the detector, and absorption of the laser

light. The acquisition time was chosen between 10-50 seconds with accumulations of 8-15 scans

that made a total scanning time of at least 30-60 minutes. Each sample was scanned 5-8 times to

confirm the consistency of the measurement and to achieve the best spectra. Some spectra

required smoothing, but most of the spectra were correct without smoothing and were baseline

corrected and normalized as needed.

4.3 Results and Discussion

4.3.1 Elemental analyses

Energy-Dispersive X-ray Spectroscopy (EDS)

Table 13

Elemental compositions and oxygen-carbon ratios of different bamboo species and their fibers

Sample

Weight % Atomic % Other Elem.

Fineness (Tex)

Fineness (Ne)

O/C from At% C O Other C O Other

Red Margin 64.01 35.99 - 70.32 29.68 - - - - 0.42

Moso 64.87 35.13 - 71.1 28.9 - - - - 0.41

Giant Gray 64.23 35.77 - 70.52 29.48 - - - - 0.42

Bissetii 65.19 34.23 0.58 71.49 28.18 0.33 Na - - 0.39

R-9 Fiber 62.50 36.98 0.52 69.03 30.67 0.30 Na 27 22 0.44

R-27 Fiber 56.56 43.44 - 63.43 36.57 - - 13 47 0.58

M-22 Fiber 51.80 47.33 0.87 59.03 40.49 0.48 Na, Si 34 17 0.69

G-23 Fiber 51.12 47.7 1.18 58.57 41.03 0.40 Ca 13 47 0.70

B-23 Fiber 51.98 47.1 0.92 59.33 40.36 0.31 Ca 21 29 0.68

Yala* 52.11 47.29 0.60 59.3 40.40 0.30 Si - - 0.68

*100% commercial bamboo viscose cloth product.

74

From the energy-dispersive X-ray spectroscopic (EDS) investigations summarized in

Table 13, it was revealed that raw bamboo specimens were mainly composed of carbon (C) and

oxygen (O). The proportions of C and O of four bamboo species in multiple specimens were

found to be consistently 64-65% and 34-36% by weight %, and 70-72% and 28-30% by atomic

% respectively. The investigation also revealed that a fractional amount of carbon reduced as the

NBFs were extracted from raw bamboo and fineness (Tex) of the fibers reduced. For example,

when raw Red Margin was subjected to processing of NBF extraction R-9 (27 Tex) and R-27 (13

Tex), the fraction of C reduced from 64.01% in raw to 62.50% in R-9 and then to 56.56% in R-

27 by weight%; similarly, 70.32% in raw to 69.03% in R-9 and then to 63.43% in R-27 by

atomic%. This was the same trend for all bamboo species and the respective NBFs. It was also

noticed that amount of C and O in commercial 100% bamboo viscose apparel product (Yala) and

in finer NBFs (R-27, B-23, G-23, and M-22) from four bamboo species were similar (Table 13).

The O/C ratios from atomic% of the raw bamboo plants were found to be almost same,

0.39-0.42. However, there are some instrumental factors such as sensitivity, calibration, and

contamination that can influence O/C ratios (Johansson et al., 2005). The O/C ratios were

increased as the NBFs were extracted to finer forms and the finer fibers showed similar ratios

(~0.70) to bamboo viscose (Table 13). This is in agreement with the reduction of the quantity of

carbon in NBFs as mentioned earlier. Since lignin is a compound with high C content, the

amount of C reduces as the raw bamboo goes through delignification. Similar results were also

observed for other fibers in previous studies (Nasser et al., 2017; Truss et al., 2016). An increase

in the O/C ratio as a result of higher oxygen concentration or the reduction in carbon means that

extracted NBFs will be more water-absorbent since it will have less hydrophobic lignin

compounds. Because of the low sensitivity, some other elements might not be detected.

However, sodium (Na), silicon (Si), nitrogen (N) and calcium (Ca) were detected as nominal

75

portions (0-0.6%) as the other elements. Assignments of these elements were based on the

assumption that the shared portion of 0-0.6% in the elemental composition of specimens was

from other elements rather than from C and O. These elements were assigned based on a

prediction of what is relevant to a fiber. So, a list of elements was selected from the Periodic

Table and the software detected the most likely elements. Though data and results from EDS are

not highly accurate, they may provide us with an understanding of elemental distribution,

presence, and changes of composition during processes.

4.3.2 X-ray Photoelectron Spectroscopy (XPS)

Like EDS, the XPS examination revealed that carbon is the most abundant element, outside

hydrogen, in bamboo and oxygen is the next. In Table 14, atomic% of carbon in four bamboo

species can be presented as 76-78% and oxygen as 20-24%. Nitrogen was detected as the third

element with atomic% of 1-4% from different XPS observations. It can be noticed from Figure

12 that N 1s peak was detected on Giant Gray and Red Margin bamboo specimens but it was not

detected on the other two bamboo specimens. Table 14 represents the amount of nitrogen in Red

Table 14

Concentration, O/C ratios and binding energies of different elements in four bamboo specimens

from XPS investigation

Sample Orbital

Binding Energy (eV)

Area FWHM Height At% O/C O/C from peak area

O/C from peak height

XPS EDS XPS

Red Margin

C 1s 289 34972 4.47 13069 77.70

0.42 0.26 0.27 O 1s 535 26364 4.15 10364 19.99

N 1s 402 1874 5.22 689 2.31

Moso C 1s 288 25017 4.89 9021 76.29

0.41 0.31 0.33 O 1s 535 22781 4.40 8667 23.71

Giant Gray

C 1s 283 40429 3.89 19216 77.37

0.42 0.27 0.29 O 1s 531 31906 3.37 16325 20.84

N 1s 397 1685 3.54 919 1.79

Bissetii C 1s 287 27521 5.18 10167 76.37

0.39 0.31 0.33 O 1s 534 24957 4.58 9818 23.63

76

Margin (2.31%) and Giant Gray (1.79%) species only. Probably, nitrogen from the environment

was detected in Giant Gray and Red Margin samples and it was not present on the scanned

surfaces of Moso and Bissetii. Since two surfaces of each strip were slightly different with

respect to fiber content, the presence of elements and quantities probably varied by the surface of

the bamboo strip that was observed. The C 1s peaks in the XPS spectra of all bamboo plants

were observed in the range of 283-289 eV binding energy and O 1s in the range of 531-535 eV.

These ranges are also reported by many other studies with cellulose-based materials (Belgacem

et al., 1995; Herzele et al., 2018; Johansson et al., 2005; Kazayawoko et al., 1999; Migneault et

al., 2015; Popescu et al., 2009; Truss et al., 2016; Wang et al., 2018; Zafeiropoulos et al., 2003).

The binding energy of N 1s was within 397-402 eV as reported by different studies (Truss et al.,

2016; Xu et al., 2013; Zhang et al., 2016). Although C 1s and O 1s peaks were clearly identified

as intense peaks in all samples, the N 1s peak was not seen in all spectra and it was not intense as

well (Figure 12). It could be environmental nitrogen on the surface of the specimens that were

detected by the spectrometer.

In Table 14, the estimation of O/C ratios from atomic%, area, and height revealed that all

three methods were consistent with each other as the values were approximately equal. The O/C

ratios of all bamboo species were equivalent which was in the range of 0.26-0.33. This value was

more accurate as it matches previous investigations of cellulose-based materials (Herzele et al.,

2018; Kazayawoko et al., 1999; Popescu et al., 2009; Truss et al., 2016; Xu et al., 2013). The

O/C ratios obtained from EDS (0.39-0.42) was slightly higher than XPS values (0.27-0.33).

77

Figure 12. X-ray photoelectron spectroscopic survey spectra of four bamboo species

From the deconvolution of C 1s and O 1s peaks using CasaXPS software as shown in

Figure 13 and Figure 14, four components of C 1s (C1-C4) and two components of O 1s (O1-O2)

were identified. Using more than 99.5% (𝑅2 > 99.5%) data of C 1s and O 1s, C1-C4 and O1-O2

components were separated. Though C1- C3 components were in all spectra, C4 was not

identified in Moso bamboo (Figure 13). The sample’s surface selection or the software’s

precision and accuracy could be the reason it was not identified. However, it can be concluded

that bamboo is composed of C 1s with C1- C4 components where binding energies were

estimated as 283-287 eV for C1, 285-289 eV for C2, 287-289 eV for C3, and 290-292 eV for the

C4 component (Table 15). This provides us with the understanding that C1 corresponds to C—C

and C—H bonding of aliphatic and aromatic carbon in lignin, extractives substances, and fatty

acids; C2 corresponds to C—O (primary and secondary) alcohol and ether-type (non-carbonyl

78

group) bonding mainly in cellulose, C3 corresponds to C═O and/or O—C—O bonding of

carbonyl and acetal groups in cellulose, C4 corresponds to O—C═O bonding of carboxyl group

of esters and carboxylic acids (Belgacem et al., 1995; Johansson et al., 2005; Kazayawoko et al.,

1999; Popescu et al., 2009; Truss et al., 2016; Xu et al., 2013; Zafeiropoulos et al., 2003; Zhou et

al., 2017).

Figure 13. Deconvoluted peaks of the components (C1-C4) of C 1s peak from XPS spectra of 4

bamboo plants: (a) Bissetii, (b) Giant Gray, (c) Moso, and (d) Red Margin bamboo.

Though O 1s spectra are often disregarded, they are very important to investigate surface

composition as the carbon atoms need to be balanced in a substance (Truss et al., 2016). In

79

Figure 14, O1 and O2 components of O 1s are identified in all four bamboo species but with

different concentration, as seen in C 1s (Table 15). The binding energies of peaks were

equivalent in all species; examples are O1 with 531-534 eV and O2 with 532-536 eV. The O 1s

peaks with such binding energies are reported to be O1 as an oxygen atom double-bonded to a

carbon atom (O—C═O, C═O) and O2 as an oxygen atom single-bonded to a carbon atom (C—

O) (Popescu et al., 2009; Truss et al., 2016). The presence of N 1s peak may be from amide

bonding in bamboo specimens.

Figure 14. Deconvoluted peaks of the components (O1 and O2) of O 1s peak from XPS spectra of

4 bamboo plants: (a) Bissetii, (b) Giant Gray, (c) Moso, and (d) Red Margin bamboo.

80

Table 15

Binding energies, atomic percentages of Carbon and Oxygen with their components in XPS

analysis of different bamboo species

C

O C1 C2 C3 C4 O1 O2

Red margin Binding energy (eV) 286.92 288.64 289.44 291.80 533.73 535.91

Atomic% 22.03 22.03 52.01 3.93 45.49 54.51

Moso Binding energy (eV) 284.18 286.41 288.83 290.98 533.19 535.67

Atomic% 11.72 18.61 58.64 11.03 48.12 51.88

Giant gray Binding energy (eV) 283.09 284.71 286.58 - 530.72 531.88

Atomic% 59.60 32.45 7.95 0.00 90.46 9.54

Bissetii Binding energy (eV) 284.15 287.30 288.01 289.54 532.70 535.03

Atomic% 15.21 68.03 3.48 13.28 52.76 47.24

As listed in Table 15, atomic percentages of different components of C 1s and O 1s were

dissimilar for different bamboo species. A combination of the selection of the surfaces for XPS

scanning, data processing, species type and age of bamboo plants are plausible reasons for such

results. Since the inner surface of the bamboo strips contain a higher amount of lignin and this

gradually decreases to the outer surfaces, the differences in the concentration of different

components of C 1s and O 1s in Table 15 are possibly due to the selection of scanned surface of

bamboo strips. The percentage concentration of C4 was the lowest carbon component is all cases.

This suggests that there is a smaller quantity of carboxylic or ester-containing groups in bamboo

than other chemical groups that contain C2 or C3 carbon atoms.

4.4 FTIR and Raman: Identifying Chemical Groups

A comparative presentation of infrared (IR) and Raman spectra obtained for untreated raw

bamboo specimens and NBFs is displayed in Figure 15. It can be seen in the spectra that only a

range between 700-4000 cm-1 of IR spectra could be investigated for peak analysis to determine

the presence of different chemical groups and behaviors. Raman spectra could exhibit

identifiable peaks within 100-4000 cm-1, giving a wider range. Moreover, within the same range,

two types of spectra could provide different peaks or the same peak with different intensity. This

81

was because IR and Raman have different sensitivity to different chemical bonding and

functional groups. For example, as FTIR is more sensitive to –OH bond stretching of water, a

wide peak between 3100-3600 cm-1 is visible but Raman spectra were unable to detect such a

peak in the range. Thus, Figure 15 can provide us with an understanding that both of these

spectroscopies would be good for chemical analysis for a material. Moreover, it should also be

mentioned that though it is said that sample preparation for Raman spectroscopy is simpler than

for FTIR, it was found to be more difficult to use some fiber samples in the Raman spectrometer

than in ATR-FTIR.

Figure 15. Comparisons of ATR-FTIR and Raman spectra of raw bamboo samples and natural

bamboo fibers (NBFs).

82

A comparative Raman spectroscopic study of the four bamboo species Bissetii, Giant

Gray, Moso, and Red Margin revealed that they have almost similar spectral patterns to each

other as shown in Figure 16. The spectra from IR were also similar to each other. This suggests

that the different bamboo species may have the same type of chemical groups, behaviors, and

Figure 16. Comparisons of Raman spectra of four bamboo species, natural bamboo fiber (NBF)

and cotton fiber.

bonds. But the spectra changed in natural bamboo fibers (NBFs), especially in the regions

between 1500- 1800 cm-1 where the intensities of different peaks in NBF (R-25) spectra were

lower than that of raw bamboo specimens (Figure 16). Though intensities of the peaks were very

83

low, they were definitely identified in NBFs specimens. There was a major difference in the

spectra between cotton fibers and NBFs as shown in Figure 16, specially in the 1500-1800 cm-1

region. There are also some peaks in NBFs which could not be matched in cotton spectra. This

establishes a reason why NBFs would exhibit some unique behaviors as compared to cotton.

Figure 17. Comparisons of Raman spectra of Red Margin bamboo, natural bamboo fibers

(NBFs) from four species and bamboo viscose fiber. [B-25, G-25, M-25, and R-25 are NBFs

from Bissetii, Giant Gray, Moso, and Red Margin bamboo plants].

Again, a comparison of the Raman spectra of four NBF specimens B-25, G-25, M-25,

and R-25 in Figure 17 exhibits that NBFs extracted from different bamboo species are almost the

same with respect to their spectral peaks and intensities. Though the peaks between 1500-1800

84

cm-1 are less intense, all other peaks were more intense and clearer in the spectra of NBFs than

raw Red Margin’s spectrum (Figure 17). However, almost all of the peaks in the spectra of NBFs

were present in the spectra of each bamboo specimens. It was also noticeable that bamboo

viscose has fewer peaks in the spectrum than NBFs’ peaks. The characteristic peaks of NBFs

within 1500-1800 cm-1 that are mainly from lignin compounds were not observed in bamboo

viscose. So, this was a clear difference between bamboo viscose and NBFs.

Since any of the spectra of the studied bamboo specimens would represent almost all

peaks in both raw bamboo specimens or NBFs, identified peaks of a Red Margin specimen were

chosen in a ATR-FTIR spectrum in Figure 18 to represent bamboo and NBFs, and a Red Margin

specimen for Raman spectrum in Figure 19. Based on the clustering of peaks because of the

presence of different chemical groups, the regions in the IR and Raman spectra can be divided

Figure 18. Different peaks and their positions in the ATR-FTIR spectrum of Red Margin

bamboo specimen.

85

Figure 19. Different peaks and their positions in the Raman spectrum of Red Margin bamboo

specimen.

into 3 portions in combination: 150-610 cm-1 band region, 630-1800 cm-1 band region, and 2700-

3600 cm-1 band region. It was observed that peaks in the IR spectra were not clearly detected

below 800 cm-1 (Figure 18) but many peaks were clearly identified between 200-800 cm-1 in

Raman spectra (Figure 19). In contrast, though some clear peaks between 2700-3600 cm-1 band

region were observed in IR spectra, only a few or no peaks in that region were detected by

Raman spectra. Moreover, peaks between 900-1160 cm-1 in IR spectra were of high intensity

(Figure 18) but these peaks were of low intensity in Raman spectra (Figure 19). The opposite

patterns were observed between IR and Raman spectra in the 1500-1800 cm-1 band region. The

above-mentioned differences explain the importance of investigating chemical behaviors of a

material by both ATR-FTIR and Raman spectroscopies.

86

Different chemical groups, bonds, and characteristics of raw bamboo specimens, NBFs, cotton,

bamboo viscose, and regular rayon from ATR-FTIR and Raman spectra are presented in Table

16. As mentioned earlier, some peaks were only observed in IR spectra, some are in Raman

spectra, and other peaks were observed in both spectra. The first region of the band 150-610 cm-1

was detected in Raman spectra of all samples. It was observed that spectra of all samples, mainly

cellulose-based, exhibited some peaks in the region. The peaks within this region were described

as due to skeletal bending, glycosidic linkage and ring deformation of C-O-H, C-C-H, C-C-O, C-

C-C, C-O, and C-O-C groups in cellulose and hemicellulose (Cabrales, Abidi, & Manciu, 2014;

Cho, 2007; Kavkler & Demšar, 2011). Though a peak within 375-379 cm-1 observed in cotton,

NBFs and bamboo specimens which is related to the crystallinity of cellulose, and C-C-C, C-O,

C-C-O bonds and ring deformation, this peak was not identified in rayon or bamboo viscose.

Moreover, some peaks in the range of 630-890 cm-1 were detected but they were not

identified in the literature. Peaks in 630-890 cm-1 can be assigned as C-H and O-H out-of-plane

bending, mono-substituted benzenes, (N-H) primary amide, C-C stretch, CH=CH (cis), and

C=C-H (vinyl compounds) bending/twisting (Socrates, 2001).

In the second 630-1800 cm-1 band region, the most number (30-40 except rayon and

bamboo viscose) of peaks were detected in all samples (Table 16, Figure 18, Figure 19). Peaks in

this region were detected either by IR or by Raman or by both spectra. A peak at ~1060 cm-1

defined as C-O-H secondary alcohol was observed in cotton and bamboo viscose but it was not

found in the spectra of bamboo and NBFs specimens. Similarly, many other peaks such as 1120-

1124, 1235-1247, 1335, 1484-1489, 1508-1514, 1660-1683, 1728-1745 cm-1 in the cotton, NBFs

and bamboo specimens were detected but they were not present in rayon or bamboo viscose

spectra. These peaks are mainly related to lignin, hemicellulose, and cellulose. Some peaks in the

second region were also identified in NBFs and untreated bamboo specimens such as 1322-1330,

87

Table 16.

Chemical bonds and band characteristics of ATR-FTIR and Raman spectra of four bamboo species, natural bamboo fibers (NBFs),

bamboo viscose, regular rayon, and cotton fibers (Alves et al., 2016; Cabrales et al., 2014; Carrillo et al., 2004; Comnea-Stancu et al.,

2017; Dai & Fan, 2011; Kavkler & Demšar, 2011; Kılınç et al., 2018; Lee et al., 2015; Migneault et al., 2015; Sanjay et al., 2018;

Schenzel & Fischer, 2001; Xu et al., 2013; Yueping et al., 2010)

Literature Cotton Bissetii B-25 NBF

Giant Gray

G-25 NBF

Moso M-25 NBF

Red Margin

R-25 NBF

Bamb. Viscose

Rayon Functional Group/Assignments

cmˉᴵ cmˉᴵ cmˉᴵ cmˉᴵ cmˉᴵ cmˉᴵ cmˉᴵ cmˉᴵ cmˉᴵ cmˉᴵ cmˉᴵ cmˉᴵ

172-252 170-287

182-277

206-267

187-280

203-282

210-277

154-288

202-272

195-284

164-233 159-221

C-O-H bending

304-308 307 308 311 309 309 307 304 309 309 309 309 C-C-O bending

318-350 331, 347

- 352 331 331 324 330 350 327, 350

353 354 C-C-C, C-O, C-C-O, ring deformation

377-383 379 378 379 375 378 376 379 377 377 - - C-C-C, C-O, C-C-O, ring deformation, crystalline peak

418-439 436 435 430, 439

413, 439

433 414 435 434 426, 434

419 420 CCC, CCO ring deformation

457-461 458 457 456 457 459 458 459 460 460 460 462 C-C-O and C-C-C bending, ring deformation, skeletal

bending

489-496 487 492 488, 495

491 493 492 - 494 492 489 491 C-O-C bending, glycosidic linkage; xylan (hemicellulose)

518-523 518 521 521 524 519 525 518 523 510 521 519 C-O-C glycosidic linkage, C-C-C ring deformation

540-542

537

539 540

537 539 - - C-O-C bending in-plane, glycosidic ring

565-575 566 569, 574

575 576 581 569 567 563 578 577 578 C-O-C bending, ring

602-609 611 600, 607

605 607 608 600 609 602 602 - 607 C-C-H bending

630-890 704-856

710, 863

692- 842

720-805

675-827

715-864

643-866

643-742

665-827 708-831

C-H and O-H out-of-plane bending, mono-substituted benzenes, (N-H) primary amide, C-C stretch, CH=CH

(cis), and C=C-H bending/twisting

896-900 896 898 895, 899

898-901

898 900 897, 899

899 895, 899

894, 897

895, 897

C-H deformation in cellulose, H-C-C bending, H-C-O bending, 1° methine bending

910 - - - 923 915 918 - 922 911 - 918 C-O-C in plane, symmetric

88


Giant Gray

G-25 NBF

Moso M-25 NBF

Red Margin

R-25 NBF

Bamb. Viscose


972-999 984-1002

982 969-999

983-988

974-995

983, 988

975, 988

981 971, 992

969, 995

983, 998

CH2, skeletal

1035-1039 1036 1032-1037

1030, 1017

1032-1037

1038 1032, 1039

1031, 1038

1032, 1038

1030, 1041

1032 1031 C-O stretching, primary alcohol, guaiacyl (lignin),

circular C–O–C stretching and contracting symmetric motion

1050-1055 1054-1057

1047-1050

1051, 1055

1052 1052, 1055

1052 1052, 1055

1051, 1053

1052, 1056

- - C-O-C symmetric stretching

1060 1060 - - - - - - - - 1063 - C-O-H 2° alcohol

1099-1105 1097 1093, 1103

1105, 1095

1094-1103

1094-1103

1095, 1103

1093, 1103

1094, 1103

1094, 1104

1096 1097 C–O–C antisymmetric stretching, C-O-C glycosidic, ring

breathing

1120-1124 1120 1121- 1126

1122 1120-1123

1122 1120, 1123

1120 1120, 1122

1120 - - C-H guaiacyl and syringyl (lignin), C-O-C glycosidic

linkage, symmetric stretching

1150-1163 1151, 1161

1172 1162, 1176

1161-1170

1150, 1161

1158-1170

1150-1160

1156-1172

1151-1161

1156 1158 C-C, C-O ring breathing, C–O–C antisymmetric

stretching, carbohydrate

1200-1205 1199-1205

1204 1202, 1197

1205 1203 1204 1202 1202, 1204

1201, 1204

1199, 1202

1199, 1203

O–H in plane bending

1235-1247 1246-1251

1232-1238

1244-1247

1238 1233, 1247

1237 1244-1249

1241 1242, 1248

- - C–C, C–O, C=O stretching, guaiacyl ring breathing

(lignin and hemicelluloses), esters

1279-1295 1279-1293

1269 1268-1281

1266 1265, 1281

1267 1265-1282

1268 1267, 1280

1266, 1275

1266 C-H bending, CH2 twisting

1317 1314-1315

1317 1312-1317

1311 1316 1311, 1319

1312, 1316

1314, 1319

1316 1313 1313 C–H wagging

1322-1328 - 1328 1328 1326 1329 1328, 1330

1326 1330 1325 - - O-H phenol group (cellulose), bending vibration in

plane

1335 1335 1338 1337 1336 1335 1334, 1336

1336 1334, 1337

1335, 1338

- - O–H in plane bending

1332-1355 1337 1336 1338-1340

- 1339 - 1341 - 1342 1339 1338, 1341

CH2 wagging, -C-O-H, lignin

1365-1366 1362-1369

1365 1365-1367

1367 1366 1365 1365 1370 1365 1365 - Symmetric CH3 deformation

1375-1379 1381 1373, 1377

1372-1379

1372-1379

1373, 1379

1373, 1380

1374, 1378

1374, 1379

1371, 1380

1374 1375 CH2, H-C-C, H-C-O, C-H deformation (cellulose and

hemicellulose)

1410-1425 1420-1427

1421, 1425

1420-1426

1424 1423 1421, 1424

1421 1422, 1425

1420 1417 - H–C–H, O–C–H in plane bending, aromatic skeletal

vibrations (lignin) and C-H deformation in plane (cellulose)

1458-1478 1474-1279

1457 1456-1460

1457 1457, 1460

1455 1454, 1463

1456, 1467

1460 1462 1462 O–H in plane bending, correlated to amorphous cellulose, C-H symmetric bending in CH3 (lignin)

1481 1481 - - - - - - - 1481 - - Correlated to cellulose crystalline

89


Giant Gray

G-25 NBF

Moso M-25 NBF

Red Margin

R-25 NBF

Bamb. Viscose


1484 1489 1488 1489 - 1485 - 1487 - 1489 - - CH2 stretch

1511 1508-1511

1503 1512 1515 1508-1513

1510-1514

1513 1506 1508 - - C=C, aromatic ring (lignin), stronger guaiacyl element

than syringyl

1578 1577 1560 1580 1580 1577 1594 1576-1578

- 1578-1580

- - C=C stretch

1601 1601 1603 1601 1603-1605

1603, 1605

1605 1601 1605 1603 1601 1601 C=C, aromatic ring (lignin)

1635-1644 1636-1640

1628-1644

1635 1631-1639

1637 1631 1638 1633 1631 - - H-O-H bending of absorbed water

1650 - 1650 1646-1650

1651 1650 1650 1651 1651 1650 - - C=O, quinines and quinine methides, adsorbed water

1662 1683 1657 1666-1670

1660 1661 1658 1667 1660 1667 - - C=O, lignin

1700 - 1702 1700-1708

1700 1699 1700 1697 1700 1702 1699 - C=O or C=C stretch, carboxylic acid, secondary amides

1735-1740 1733-1742

1732 1733, 1748

1732 1733-1745

1733, 1741

1728 1732 1738 - -

C=O stretching of an ester, free carbonyl groups, stretching of acetyl or carboxylic acid (-COOH,

hemicelluloses), non-conjugated carbonyl vibration from lignin

2736 - - 2734-2742

2731 2723, 2743

- 2739 2736 2735 - - CH methine

2850 2850-2851

2850 2855 2850 2844-2855

2850 2855 2850 2845 2849 2849 CH2 symmetrical stretching

2897-2944 2892- 2948

2897 2901, 2948

2893, 2916

2890-2932

2921-2939

2897 2891, 2937

2932 2895 2895 CH2, C–H stretching (expanding and contracting

vibration)

3100-3600 3100-3600

3000-3600

3000-3600

3000-3600

3000-3600

3000-3601

3100-3600

3100-3600

3100-3600

3100-3600

3100-3600

O–H stretching, intra- and intermolecular H bonds;

3240-3285 3286-3292

3242-3290

3249, 3281

3242-3290

3242-3290

3242-3291

3242-3292

3242-3293

3256, 3288

- - Strongly h-bonded OH

3330 3335 3343 3331-3334

3344 3337 3341 3335 3344 3325 3330 3330 Moderately h-bonded OH

3370 3385 3365 3369-3384

3365 3365 3366 3364, 3385

3366 3375 - - Weakly h-bonded OH

Note: B-25, G-25, M-25, and R-25 are the natural bamboo fibers (NBFs) from Bissetii, Giant gray, Moso and Red Margin bamboo species respectively. Different

peak centers/band values in green fonts were only detected by Raman, orange fonts were only detected by ATR-FTIR and black fonts were detected by both

spectroscopies.

90

1646-1651 cm-1 related phenolic –OH and quinines (C=O) groups but they were not found in

cotton, rayon or bamboo viscose specimens. A peak at ~1700 cm-1 was identified in the spectra

of bamboo specimens which was not found to be described in the literature. This peak can be

defined as C=O or C=C stretch, carboxylic acid, secondary amides (Socrates, 2001).

The third 2700-3600 cm-1 band region is mainly detected by ATR-FTIR spectra and the

peaks in this region were mainly related to stretch due to weakly, moderately or strongly

hydrogen-bonded –OH group (Table 16). However, peaks at 3240-3293 and 3364-3385 cm-1,

which are related to intermolecular and intramolecular H-bond stretching, were present in all

specimens except bamboo viscose and rayon. Another distinct characteristic peak (within 2723-

2742 cm-1) was also noticed in the spectra of bamboo and NBFs specimens in this region which

was described as stretch due to –CH- or methine group.

Thus, the investigation of chemical groups, bonds and behaviors provide us with an

insight that though cotton, bamboo species, NBFs, rayon and bamboo viscose are cellulose-based

materials, there were some definite distinctions between the regenerated cellulose materials

(conventional rayon and bamboo viscose) and natural cellulosic materials such as cotton, raw

bamboo, and NBFs. It was also observed that bamboo viscose and conventional rayon had

similar peaks in the spectra to each other and this was reasonable as they are generally pure

cellulose. Furthermore, it was revealed that there were some unique characteristic peaks

providing information on chemical behavior in raw bamboo specimens and NBFs. It should be

noted that Table 16 represents a comprehensive list of characteristic peak and relevant chemical

information of different materials but since some peaks with low intensities are also listed, there

might be some inexactly identified peaks. It is also possible that some peaks from unknown

chemical groups may be unidentified.

91

4.5 Conclusions

Elemental analyses of four bamboo species and their fibers by energy-dispersive X-ray

spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) revealed that the materials are

mainly composed of carbon (C) and oxygen (O) along with hydrogen elements. Some other

elements were also identified such as nitrogen (N), sodium (Na), calcium (Ca) and silicon (Si).

The composition of bamboo species by EDS was estimated as 64-65% C and 34-36% O by

weight %, and 70-72% C and 28-30% O by atomic %. However, XPS produced slightly different

composition: 76-78% C and 20-24% O by atomic %. The O/C ratio was found to be increased as

the NBFs are separated from lignin. The O/C ratios were determined as 0.39-0.42 for bamboo

species in EDS but this was lower in XPS as 0.26-0.33. The ratio was found to be 0.58-0.70 in

NBFs as assessed by EDS. The higher O/C value of NBF suggests that it is more moisture-

wicking than raw bamboo. XPS survey on four bamboo species also revealed that C 1s and O 1s

peaks with different components. After deconvolutions, C 1s was identified with four

components (C1-C4) of four types of chemical bonding at different binding energies: C1 as C—C

and C—H, C2 as C—O, C3 as C═O and/or O—C—O, and C4 as O—C═O bonding. The analysis

of O 1s peak also revealed O1 as O—C═O and/or C═O and O2 as C—O type chemical bonding.

The N 1s peak was also detected in some specimens. Continuing studies would confirm the

presence of other elements if any. Results from this investigation on EDS and XPS would help to

determine chemical natures of bamboo and its fibers.

The investigation of raw bamboo specimens and NBFs from four bamboo species proved that

using ATR-FTIR and Raman spectroscopies, a better chemical analysis of a material such as

bamboo can be executed since each spectroscopy has the ability to detect some unique peaks or

the same peak with different sensitivities. A series of both types of spectra of four bamboo plants

92

also revealed that they have an almost-similar pattern in spectra. Though different in intensities,

patterns of spectra of NBFs were also found to be comparable. This provides us a conclusion that

both raw bamboo plants and their NBFs may carry analogous chemical groups, bonds, and

behaviors which was shown in the analysis of characteristic peaks. There were some obvious

differences in the spectra of cotton, regular rayon, and bamboo viscose when compared with the

spectra of each bamboo and its NBF. Bamboo and NBF had some unique characteristic peaks

that were not identified in either cotton or viscose/rayon. These unique peaks were mainly from

lignin, hemicellulose, cellulose, and its crystallinity. Moreover, some peaks were detected in

both IR and Raman spectra which were not found in previously reported studies. This study

provides a comprehensive list of chemical information and behaviors of bamboo plants and their

natural fibers. Further in-depth investigation of more species using other spectroscopies with

larger samples would be required to strengthen the results of this study.

4.6 References

Abbott, L. C., Batchelor, S. N., Smith, J. R. L., & Moore, J. N. (2010). Resonance Raman and

UV-visible spectroscopy of black dyes on textiles. Forensic Science International,

202(1–3), 54–63. https://doi.org/10.1016/j.forsciint.2010.04.026

Alves, A. P. P., de Oliveira, L. P. Z., Castro, A. A. N., Neumann, R., de Oliveira, L. F. C.,

Edwards, H. G. M., & Sant’Ana, A. C. (2016). The structure of different cellulosic fibres

characterized by Raman spectroscopy. Vibrational Spectroscopy, 86, 324–330.

https://doi.org/10.1016/j.vibspec.2016.08.007

Belgacem, M. N., Czeremuszkin, G., Sapieha, S., & Gandini, A. (1995). Surface characterization

of cellulose fibres by XPS and inverse gas chromatography. Cellulose, 2(3), 145–157.

https://doi.org/10.1007/BF00813015

Cabrales, L., Abidi, N., & Manciu, F. (2014). Characterization of Developing Cotton Fibers by

Confocal Raman Microscopy. Fibers, 2(4), 285–294. https://doi.org/10.3390/fib2040285

Cao, Y., Shen, D., Lu, Y., & Huang, Y. (2006). A Raman-scattering study on the net orientation

of biomacromolecules in the outer epidermal walls of mature wheat stems (Triticum

aestivum). Handbook of Environmental Chemistry, Volume 5: Water Pollution, 97(6),

1091–1094. https://doi.org/10.1093/aob/mcl059

93

Carrillo, F., Colom, X., Suñol, J. J., & Saurina, J. (2004). Structural FTIR analysis and thermal

characterisation of lyocell and viscose-type fibres. European Polymer Journal, 40(9),

2229–2234. https://doi.org/10.1016/j.eurpolymj.2004.05.003

Cho, L. (2007). Identification of textile fiber by Raman microspectroscopy. Forensic Science

Journal, 6(1), 55–62. Retrieved from fsjournal.cpu.edu.tw

Comnea-Stancu, I. R., Wieland, K., Ramer, G., Schwaighofer, A., & Lendl, B. (2017). On the

Identification of Rayon/Viscose as a Major Fraction of Microplastics in the Marine

Environment: Discrimination between Natural and Manmade Cellulosic Fibers Using

Fourier Transform Infrared Spectroscopy. Applied Spectroscopy, 71(5), 939–950.

https://doi.org/10.1177/0003702816660725

Dai, D., & Fan, M. (2011). Investigation of the dislocation of natural fibres by Fourier-transform

infrared spectroscopy. Vibrational Spectroscopy, 55(2), 300–306.

https://doi.org/10.1016/j.vibspec.2010.12.009




Garside, P., & Wyeth, P. (2016). Identification of Cellulosic Fibres by FTIR Spectroscopy:

Differentiation of Flax and Hemp by Polarized ATR FTIR. Studies in Conservation,

51(3), 205–211.

Herzele, S., van Herwijnen, H. W. G., Edler, M., Gindl-Altmutter, W., & Konnerth, J. (2018).

Cell-layer dependent adhesion differences in wood bonds. Composites Part A: Applied

Science and Manufacturing, 114(January), 21–29.


Hui, B., & Li, J. (2016). Low-temperature synthesis of hierarchical flower-like hexagonal

molybdenum trioxide films on wood surfaces and their light-driven molecular responses.

Journal of Materials Science, 51(24), 10926–10934. https://doi.org/10.1007/s10853-016-

0304-y

Johansson, L. S., Campbell, J. M., Fardim, P., Hultén, A. H., Boisvert, J. P., & Ernstsson, M.

(2005). An XPS round robin investigation on analysis of wood pulp fibres and filter

paper. Surface Science, 584(1), 126–132. https://doi.org/10.1016/j.susc.2005.01.062

Kavkler, K., & Demšar, A. (2011). Examination of cellulose textile fibres in historical objects by

micro-Raman spectroscopy. Spectrochimica Acta - Part A: Molecular and Biomolecular

Spectroscopy, 78(2), 740–746. https://doi.org/10.1016/j.saa.2010.12.006

Kazayawoko, M., Balatinecz, J. J., & Sodhi, R. N. S. (1999). X-ray photoelectron spectroscopy

of maleated polypropylene treated wood fibers in a high-intensity thermokinetic mixer.

Wood Science and Technology, 33(5), 359–372. https://doi.org/10.1007/s002260050122

94

Kılınç, A. Ç., Köktaş, S., Seki, Y., Atagür, M., Dalmış, R., Erdoğan, Ü. H., … Seydibeyoğlu, M.

Ö. (2018). Extraction and investigation of lightweight and porous natural fiber from

Conium maculatum as a potential reinforcement for composite materials in

transportation. Composites Part B: Engineering, 140(November 2017), 1–8.


Kyropoulou, D. (2013). Scanning electron microscopy with energy dispersive X-ray

spectroscopy: An analytical technique to examine the distribution of dust in books.

Journal of the Institute of Conservation, 36(2), 173–185.

https://doi.org/10.1080/19455224.2013.822402

Lee, C. M., Kafle, K., Belias, D. W., Park, Y. B., Glick, R. E., Haigler, C. H., & Kim, S. H.

(2015). Comprehensive analysis of cellulose content, crystallinity, and lateral packing in

Gossypium hirsutum and Gossypium barbadense cotton fibers using sum frequency

generation, infrared and Raman spectroscopy, and X-ray diffraction. Cellulose, 22(2),

971–989. https://doi.org/10.1007/s10570-014-0535-5

Li, J., Bi, J., Song, X., Qu, W., & Liu, D. (2019). Surface and Dynamic Viscoelastic Properties

of Cork from Quercus variabilis. Bioresources.Com, 14(1), 607–618.



https://doi.org/10.1007/s12221-011-0095-3

Migneault, S., Koubaa, A., Perré, P., & Riedl, B. (2015). Effects of wood fiber surface chemistry

on strength of wood-plastic composites. Applied Surface Science, 343, 11–18.

https://doi.org/10.1016/j.apsusc.2015.03.010

Nasser, R. A., Mansour, M. M. A., Salem, M. Z. M., Ali, H. M., & Aref, I. M. (2017). Study of

Mold Invasion on the Surface of Wood/Polypropylene Composites Produced from

Aqueous Pretreated Wood Particles, Part 2: Juniperus procera Wood-Branch.

BioResources, 12(2), 4078–4092. https://doi.org/10.15376/biores.12.2.4187-4201



https://doi.org/10.1186/s40691-015-0054-5

Ouyang, L., Huang, Y., & Cao, J. (2014). Hygroscopicity and characterization of wood fibers

modified by alkoxysilanes with different chain lengths. BioResources, 9(4), 7222–7233.

https://doi.org/10.15376/biores.9.4.7222-7233

Pakdel, H., Cyr, P. L., Riedl, B., & Deng, J. (2008). Quantification of urea formaldehyde resin in

wood fibers using X-ray photoelectron spectroscopy and confocal laser scanning

microscopy. Wood Science and Technology, 42(2), 133–148.

https://doi.org/10.1007/s00226-007-0155-4

Popescu, C. M., Tibirna, C. M., & Vasile, C. (2009). XPS characterization of naturally aged

wood. Applied Surface Science, 256(5), 1355–1360.

95


Rocky, B. P., & Thompson, A. J. (2018). Production of Natural Bamboo Fibers-3: SEM and

EDX Analyses of Structures and Properties. AATCC Journal of Research, 5(6), 27–35.






Schenzel, K., & Fischer, S. (2001). NIR FT Raman spectroscopy - A rapid analytical tool for

detecting the transformation of cellulose polymorphs. Cellulose, 8(1), 49–57.

https://doi.org/10.1023/A:1016616920539

Sepe, R., Bollino, F., Boccarusso, L., & Caputo, F. (2018). Influence of chemical treatments on

mechanical properties of hemp fiber reinforced composites. Composites Part B:

Engineering, 133, 210–217. https://doi.org/10.1016/j.compositesb.2017.09.030

Socrates, G. (2001). Infrared and Raman characteristic group frequencies: tables and charts

(3rd ed.). John Wiley & Sons, Inc., 605 Third Avenue, New York, NY 10158-0012,

USA.

Thumsorn, S., Srisawat, N., On, J. W., & Hamada, H. (2014). Crystallization Kinetics and

Thermal Resistance of Bamboo Fiber Reinforced Biodegradable Polymer Composites.

Proceedings of PPS-29, 319, 316–319. https://doi.org/10.1063/1.4873790

Tolessa, A., Woldeyes, B., & Feleke, S. (2017). Chemical Composition of Lowland Bamboo

(Oxytenanthera abyssinica) Grown around Asossa Town, Ethiopia. World Scientific

News, 74, 141–151.

Truss, R. W., Wood, B., & Rasch, R. (2016). Quantitative surface analysis of hemp fibers using

XPS, conventional and low voltage in-lens SEM. Journal of Applied Polymer Science,

133(8). https://doi.org/10.1002/app.43023

Wang, S., Wu, L., Hu, X., Zhang, L., O’Donnell, K. M., Buckley, C. E., & Li, C. Z. (2018). An

X-ray photoelectron spectroscopic perspective for the evolution of O-containing

structures in char during gasification. Fuel Processing Technology, 172(October 2017),

209–215. https://doi.org/10.1016/j.fuproc.2017.12.019






https://doi.org/10.1177/0040517509337633

96

Zafeiropoulos, N. E., Vickers, P. E., Baillie, C. A., & Watts, J. F. (2003). An experimental

investigation of modified and unmodified flax fibres with XPS, ToF-SIMS and ATR-

FTIR. Journal of Materials Science, 38(19), 3903–3914.

https://doi.org/10.1023/A:1026133826672

Zhang, Y., Zhang, W., & Lu, W. (2016). Effect on tensile strength of wood-based carbon fiber

impregnated by boron. BioResources, 11(2), 5075–5082.


Zhou, D., Guo, X., Yan, S., & Di, M. (2017). Combined surface treatment of wood plastic

composites to improve adhesion. BioResources, 12(2), 3965–3975.


----------------------۞-----------------------

97

CHAPTER 5. INVESTIGATION AND COMPARISON OF ANTIBACTERIAL

PROPERTY OF BAMBOO PLANTS, NATURAL BAMBOO FIBERS AND

COMMERCIAL BAMBOO VISCOSE TEXTILES

5.1 Abstract

This study was conducted with 12 commercial bamboo viscose textiles, conventional rayon

fabric, raw cotton fibers and fabric, four bamboo plant species and 12 natural bamboo fiber

(NBF) samples for antibacterial activity using Staphylococcus aureus and Klebsiella

pneumoniae. The accuracy and efficacy of test methods were investigated and modified for

antibacterial assessment. The spectrophotometric method was found to be less effective when

bacterial reduction is not very high as bamboo and NBF samples with low

antibacterial/antimicrobial activity were tested. The revised viable plate counting technique was

very consistent and effective when tested materials were in fiber, fabric or crushed forms and

tested in sterilized and non-sterilized states. Results revealed that only one bamboo viscose

showed antibacterial activity. A majority of the specimens from bamboo plant species and NBFs

showed a measurable percentage reduction of bacteria against K. pneumoniae (8-95%) but had

poor results against S. aureus (3-50%). These results are interpreted to be due to the presence of

both bacteria-killing and promoting compounds found in the bamboo plant specimens and the

NBFs. Overall, NBFs showed higher reduction of bacteria than raw bamboo specimens.

However, due to the presence of bacteria from the environment, some NBF specimens showed a

98

greater number of colonies and thus a negative reduction of bacteria when sterilization of the

fiber specimens was not performed prior to the experiment protocol.

KEYWORDS: Antibacterial fibers; Antibacterial test; Viable plate counting; Antibacterial

activity of fibers; Bamboo viscose textiles; Bacterial reduction.

5.2 Introduction

With the advancement of textile technology, the uses of textiles are not limited to apparel,

clothing, coverings, or protection against the weather. Technical textiles such as medical textiles,

geotextiles, and smart textiles are being developed for specialized uses. Textiles because of their

nature are ideal substrates for providing antibacterial property. Currently, textiles and apparel

with antibacterial/antimicrobial, antifungal and anti-mildew properties are very important for use

in medical clothing, therapeutic clothing, wound healing, and protective clothing as well as

regular daily use. The necessity and demand for such products has led to innovation and

development of antibacterial textiles (Abdel-Mohsen et al., 2013; Budama, Çakir, Topel, &

Hoda, 2013; Burnett-Boothroyd & McCarthy, 2011; Cheng, Ma, Li, Ren, & Huang, 2014;

Chung, Lee, & Kim, 1998; Comlekcioglu, Aygan, Kutlu, & Kocabas, 2017; Gokarneshan,

Nagarajan, & Viswanath, 2017; Ibrahim, El-Zairy, El-Zairy, Eid, & Ghazal, 2011; Ma, Sun, &

Sun, 2003; Prusty, Das, Nayak, & Das, 2010; Ren et al., 2017; Shahid et al., 2012; Simoncic &

Tomsic, 2010; Tanaka, Kim, Oda, Shimizu, & Kondo, 2011; Vroman & Tighzert, 2009;

Williams et al., 2006). Accordingly, the research and the production of antibacterial textiles has

grown to help meet the demand (Gupta & Bhaumik, 2007). Properties can be developed in the

products by special treatment during dyeing, wet processing, finishing or any other process

stages (Bhuiyan, Hossain, Zakaria, Islam, & Uddin, 2017; Comlekcioglu et al., 2017; Gupta &

Bhaumik, 2007; Ibrahim et al., 2011; Manickam & Thilagavathi, 2015; Morais, Guedes, &

99

Lopes, 2016; Patel & Tandel, 2005; Shalini & Anitha, 2016; Zhang, Chen, Ji, Huang, & Chen,

2003). A challenge has been to develop chemical compounds that can provide antibacterial

activity in industrial processing, as currently they are most often toxic and harmful to the human

body and health (Budama et al., 2013; Cheng et al., 2014; Morais et al., 2016; Shalini & Anitha,

2016). In contrast, natural compounds that provide antibacterial property are considered more

human-friendly (Gokarneshan et al., 2017). Consequently, there are numerous efforts to develop

antibacterial properties from natural materials and processes, such as natural antibacterial activity

from plants or microorganisms in fibers, pigments or dyes (Burnett-Boothroyd & McCarthy,

2011; Cheng et al., 2014; Comlekcioglu et al., 2017; Manickam & Thilagavathi, 2015; Shahid et

al., 2012). Moreover, if a material has natural antibacterial activity it could prove more durable

as part of the material that would not wash away as opposed to artificially added antibacterial

compounds.

Interestingly, bamboo has been reported as naturally antibacterial and this property is

expected to be retained if the fibers are extracted in their natural form along with some non-

fibrous trace elements. Since most of the existing natural and synthetic fibers do not have

antibacterial activity, but rather some promote bacteria growth (Budama et al., 2013;

Comlekcioglu et al., 2017; Gupta & Bhaumik, 2007; Ibrahim et al., 2011; Morais et al., 2016;

Shalini & Anitha, 2016), extraction of NBFs with such activity is of great interest. Studies have

concluded that extracts from bamboo leaves have shown antibacterial activity against some

bacteria (Singh et al., 2010). Tanaka et al. (2011) investigated the inhibition of extract from

Moso bamboo shoot skins against Staphylococcus aureus and reported that it exhibited

antibacterial activity. Moreover, different parts of bamboo plants (roots, leaves, skins) have

already been used for manufacturing preservatives and medicinal products (Keski-Saari et al.,

100

2008; Nirmala, Bisht, & Laishram, 2014; Quitain, Katoh, & Moriyoshi, 2004; Tanaka et al.,

2011; Tanaka, Shimizu, & Kondo, 2013; Tanaka et al., 2014). These studies on multiple bamboo

species confirmed that the plants possess antibacterial activity. It was also shown that bamboo

culms exhibited very high antibacterial property and fibers are mainly extracted from the culms

(Tanaka et al., 2014). Therefore, it can be proposed that natural fibers from bamboo have the

potential to retain antibacterial compounds, for example, phenolic compounds and lipids

(Gokarneshan et al., 2017; Mishra, Behera, & Pal, 2012; Nirmala et al., 2014; Quitain et al.,

2004), and thus antibacterial properties. Some studies have indicated that NBFs extracted from

the bamboo will have antibacterial properties (Afrin, Kanwar, Wang, & Tsuzuki, 2014; Afrin,

Tsuzuki, Kanwar, & Wang, 2012; Chen, Wang, Xu, & Sun, 2015; Waite, 2009; Zupin &

Dimitrovski, 2010).

5.2.1 Methods for Antibacterial Activity Assessment

Though there are different methods developed by AATCC, ISO, ASTM, and many other

organizations, most of the methods are either qualitative or less precise quantitative methods and

results vary by different factors such as sample preparation, size, shape, technique, and other

parameters. Consequently, there are misunderstandings in industry and the market place about

what is being measured (Burnett-Boothroyd & McCarthy, 2011; Williams et al., 2006).

The Agar disc diffusion method or parallel streak method (AATCC 147-2016, 2018;

AATCC 90-2016, 2018; ISO 20645, 2004) has been employed for many years relying on a

qualitative assessment. Since a clear inhibition zone around the specimens is required to be

measured, the quantitative assessment with this method has a limited accuracy when the

antibacterial activity of the specimen is low. An example is a result of zero antibacterial activity

which could be misleading (Abdel-Mohsen et al., 2013; Budama et al., 2013; Cheng et al., 2014;

101

Comlekcioglu et al., 2017; Ibrahim et al., 2011; Manickam & Thilagavathi, 2015; Sarkar &

Appidi, 2009; Shahid et al., 2012; Xue, Chen, Yin, Jia, & Ma, 2012). In fact, the lack of a zone

of inhibition or unclear inhibition zone is not always indicative of the lack of antibacterial

property (Monticello & Askew, 2013). Thus, a specimen with very low antibacterial properties

may sometimes be inappropriately graded as a non-antibacterial (Hardin, Wilson, Dhandapani, &

Dhende, 2009) or a reverse problem may arise. If the number of bacteria is less than the

antibacterial compounds in the specimen, an inhibition zone may be clear or seen. Moreover, a

material with low activity may show a wide zone of inhibition if it is subjected to a lower

number of bacteria by the higher amount of antibacterial compounds/agents or by quick

deactivation/death of bacteria that are less durable (Monticello & Askew, 2013). On the other

hand, some materials may promote bacterial growth rather than inhibition. So, there may be

growth of colony underneath the plated sample (Budama et al., 2013; Sarkar & Appidi, 2009;

Shateri Khalil-Abad & Yazdanshenas, 2010) or a higher number of colonies then the control

which leads to negative percentage of bacterial reduction (Afrin et al., 2012; Ma et al., 2003; Xi,

Qin, An, & Wang, 2013). Most of the investigation described the negative results as no

antibacterial property (Xi et al., 2013). Such results may occur due to inconsistent sample

preparation, presence of some test-bacteria or other microorganisms already on the sample, or

promoted growth by the specimens. Though the percentage reduction of bacteria by bacterial

counting is quantitatively measured exposing fabric specimens to the bacterial culture for a

certain time (0—24 h) in standard methods, testing of non-fabric samples such as fibers, small

particle samples (dyes, pigments) are not covered well by these AATCC, ASTM or ISO

methods.

102

In Optical density (OD) or turbidity, bacteria in an inoculated culture (bacteria with

nutrient broth) is measured by a spectrophotometer after incubating the culture with samples

mixed into the liquid (Comlekcioglu et al., 2017; Prusty et al., 2010; Tanaka et al., 2011, 2013).

Again, a significant change in optical density or turbidity is required to estimate a difference in

the reduction of bacteria. When a small number of bacteria are killed, the change in turbidity is

almost “zero”. So, it is difficult to identify if the sample has any antibacterial property.

The core purposes of this study were 1) practicing and modifying antibacterial techniques

that may be applied for textile material in any form, 2) assessing the activity of four bamboo

species and their respective fibers (NBFs), 3) comparison of the results with 15 commercial

fibers and/or fabrics, and 4) assessing different conditions and factors that may affect the tests.

Bacteria (microbes) for Assessment

Generally, a gram-positive and a gram-negative bacterium are recommended for antibacterial

activity tests for textile materials. Staphylococcus aureus, a gram-positive facultative bacterium

that can grow even without oxygen, is one of the most common pathogens that live on human

skin and causes skin infections, food poisoning, respiratory infections and many others issues

(Tanaka et al., 2011). It has been repor ted that half a million people are hospitalized due to S.

aureus, with 50, 000 deaths each year caused in the USA (Schlecht et al., 2015). Therefore,

testing with S. aureus is highly recommended, especially with products that interact with the

human body. Klebsiella pneumoniae (K. pneumoniae) is one of the most common gram-

negative, facultative anaerobic, bacterium that lives on skin, in the mouth and intestine, and may

cause many serious diseases such as pneumonia, urinary tract infections and liver diseases

(Paczosa & Mecsas, 2007; Vading, Nauclér, Kalin, & Giske, 2018). Thus, S. aureus and K.

pneumoniae bacteria were selected for this study.

103

5.3 Methodology

5.3.1 Materials

Fresh culms of four bamboo species directly from the field were provided by Lewis Bamboo,

Inc., Oakman, Alabama. The species were Bissetii (Phyllostachys Bissetii), Giant Gray

Table 17

Names and compositions of different commercial textile products and relevant information

Sample initials

Type of the product Composition of sample Price Retailer/supplier

RT Regular rayon, twill fabric 100% RR - Dharma Trading Co.

BV Bamboo viscose cloth 100% BV - Dharma Trading Co.

AR Bamboo Sweater Tank (Magenta) 100% BV $19.99 Ash & Rose

Yala Bamboo Dreams Pillowcases®

(White) 100% BV $20.00 Yala Designs

BSA Men's T-Shirts (white) 95% BV+5% S $29.99 Bamboosa® LLC

BB Bamboo V-Neck Tee (White) 70% BV+30% C $19.95 Bambu Batu

BBB Bamboo Short-Sleeve T-Shirts

(Black) 70% BV+30% C $39.00 Big Boy Bamboo

Cari Bamboo Athletic V-Neck

(Caribbean Breeze) 40% BV+55% C+5% S $12.00 Cariloha® Bamboo

FD Spun Bamboo Tee (Cream) 70% BV+30% C $22.00 Faerie's Dance

FF Women's Bamboo Motion-V

(Pacific Blue) 68% BV+29% P+3% S $29.95 Free Fly Apparel®

GA Bamboo Yoga Pants (True Black) 60% BV+26% C+14% S $24.99 Green Apple Active

NCC Men's Turtleneck shirt (Black) 70% BV+25% C+5% S $19.00 Natural Clothing Company

Piko Off the Shoulder Short Sleeve (Off

White) 95% BV+5% S $24.99 Piko Clothing

UCF Untreated cotton fabrics 100% Cotton fabric - Testfabrics Inc.

RCF Raw cotton fibers Raw cotton fibers from

plants -

Alabama Cooperative Extension System

BCF Bleached cotton fibers Mildly bleached cotton

fibers - RCF bleached in lab

Note: RR = regular rayon; BV = bamboo viscose; S = spandex; and C = Cotton; P = Polyester.

(Phyllostachys nigra 'henon'), Moso (Phyllostachys edulis/ pubescens) and Red Margin

(Phyllostachys rubromarginata). Sigma-Aldrich, USA was used as the source for: sodium

hydroxide/NaOH (beads, AG*), sodium bicarbonate/NaHCO3 (AG), sodium silicate/Na2SiO3

(RG), sodium triphosphate/Na5P3O10 (85%, TG), sodium sulfite/Na2SO3 (≥ 98%), and acetic

acid/CH3COOH (≥ 99%, AG); hydrogen peroxide/H2O2 (30% w/w, AG) was purchased from

104

VWR International, LLC, USA; from Consos, Inc. USA: scouring agent (Consoscour GSRM),

wetting/penetrating agent (Consamine JDA), and bleaching agent (Consobleach CIL) were

collected. Additionally, fabric softener was collected from a local Publix Super Market, Inc.,

USA (Free & Clear Ultra Fabric Softener). Details about different commercial fabrics, apparel,

and fibers used in this study are reported in Table 17.

Note: *AG = ACS (American Chemical Society) grade; *RG = reagent grade; *TG = technical grade.

5.3.2 Equipment

The following equipment was used: milling machine/rolling mill (Rolling Mill Division, Stanat

Manufacturing Co. Inc, NY, USA), Launderometer (AATCC Launder-Ometer, Atlas material

testing Technology LLC), Dryer (GCA corporation, Thelco Precision Scientific Laboratory

Oven, Model 18), conditioning cabinet/Temperature and Humidity Environmental Test Chamber

(Associated Environmental Chamber), Autoclave (Consolidated Stills & Sterilizers machine),

Spectrophotometer (Genesys 10 UV Spectrophotometer, Thermo Electron Corporation), Vortex

mixer (Vortex-Genie, Scientific Industries, Inc.), Ion sputter coater (Leica, MCM-200 Ion

Sputter Coater), SEM— Apreo S HiVac (Thermo Fisher Scientific) and FEI Quanta 200 3D.

5.3.3 Extractions of Natural Bamboo Fibers

The NBFs were extracted from four bamboo species followed by pre-processing, delignification

and modifications as discussed in Part 1. Pre-processing or initial treatments involved splitting of

fresh culms, crushing/pressing multiple times in milling machine by applying gentle pressure to

avoid excess breakage of fibers, soaking with the chemical reactants in recipe 0 (as in Table 18),

combing by steel combs and pressing in the milling machine. The nomenclature of the extracted

NBFs are as follows; the initial of the name of the bamboo species is followed by the specific

route (number) where “R” is for Red Margin, “B” is for Bissetii, “M” is for Moso and “G” is for

Giant Gray. Since some NBF specimens exhibited positive and prospective results in different

105

physical, mechanical and chemical tests, the following fibers were selected for antibacterial

investigation. The extraction processes of the selected NBFs are discussed below:

R-1: this was longest NBFs from Red Margin after initial treatment and with recipe 0.

R-9: a treatment with recipe 1 (Table 18) was applied to R-1 followed by finishing treatments:

washing, neutralizing, warm and cold washing, and drying.

B-16: after initial processing, recipe 0 and recipe 2 were applied consecutively and then finishing

treatments were applied.

Table 18

Different chemicals and conditions applied to different stages of natural bamboo fiber (NBF)

extraction

M-21/G-21: initial treatments, recipe 0, recipe 3, and finishing treatment were executed one after

another.

M-22: initial treatments, recipe 0, recipe 5 along with 20 g/L of fabric softener, and then the

finishing treatment were performed respectively.

G-23/B-23: initial treatments, recipe 0, recipe 5 along with 20 g/L of fabric softener, recipe 4

were applied respectively followed by finishing steps.

M-25/G-25/B-25: recipe 7 was applied to G-23/B-23/M-23 before finishing treatments.

106

R-27: initial treatments, recipe 0, recipe 6, recipe 4 and then recipe 7 were applied one-by-one

and fibers were yielded after the finishing steps.

5.3.4 Sample Preparation for antibacterial tests

Each bamboo species was crushed separately in a milling machine including their exodermis and

endodermis. These specimens were dried and raw bamboo samples were prepared. Each fiber

and fabric sample (Table 17) was cut into small pieces by using scissors and then stored

separately in either glass vials or standard reclosable polyethylene Ziploc bag. For sterilization,

to remove any in situ bacteria, specimens were inserted into sterilization pouches of 3.5” ×

10” or 90 𝑚𝑚 × 260 𝑚𝑚 sizes and autoclaved by applying the steam method of at 121 °C for

20 minutes in Consolidated Stills & Sterilizers m/c.

5.3.5 Antibacterial Tests and Assessments

This study on antibacterial tests, preparation, methods and other relevant information used from

the standard methods of AATCC, ASTM, ISO, and TAPPI (AATCC 100-2012, 2018; AATCC

147-2016, 2018; AATCC 90-2016, 2018; ASTM E2149-13a, 2013; ISO 20645, 2004; TAPPI

T205 sp-02, 2006). The gram-positive bacterium Staphylococcus aureus, as referenced in ATCC

(American Type Culture Collection) No. 6538, and the gram-negative bacterium Klebsiella

pneumoniae, as referenced in ATCC No. 4352 were used for the study.

Spectrophotometric technique (Optical Density, OD600)

A 1mL culture of approximate concentration of 109 CFU/mL from each bacterium was added to

9 mL tryptic soy broth (TSB) in a test tube. The McFarland equivalence turbidity standard (3~4)

and visual comparison card (Thermo Scientific™ Remel) were used to match turbidity of the

cultures to achieve an approximate concentration of 109 CFU/mL. Then 1 g of fiber or fabric

sample was added to each test tube. This was done separately for both bacteria. All the samples

107

were incubated for 20 h at 37 °C. A control sample was also incubated that contained no fiber

samples. The percentage reduction of bacteria (%𝑅) was determined by optical density (OD),

turbidity or absorbance using equation (1). The optical density (OD) is defined as the amount of

light that passes through a bacterial solution and it estimates the concentration of bacteria in a

suspension. A lower OD value means a higher reduction in bacteria. In this method, the optical

density of the control culture solution of bacteria (𝑂𝐷𝑐𝑜𝑛𝑡𝑟𝑜𝑙), and optical density of the culture

solution of bacteria that is in contact with a sample for 18-24 h time (𝑂𝐷𝑠𝑎𝑚𝑝𝑙𝑒) were measured

by spectrophotometer (light with 600 nm wavelength).

% 𝑅𝑒𝑑𝑢𝑐𝑡𝑖𝑜𝑛 =(𝑂𝐷𝑐𝑜𝑛𝑡𝑟𝑜𝑙 − 𝑂𝐷𝑠𝑎𝑚𝑝𝑙𝑒)

𝑂𝐷𝑐𝑜𝑛𝑡𝑟𝑜𝑙× 100% … … … … (1)

This technique was employed in previous investigations for textiles fibers, yarns, fabrics, dyes

and other materials (Afrin et al., 2012; Shahid et al., 2012). The test was performed separately

with small-cut fiber/fabric (less than 1 cm long) and large-cut (1~2 cm long) samples to see if the

size of the specimen affects test results. The optical density of the culture was measured by

taking 1 mL culture solution from each sample in cuvettes carefully so that no fiber/fabric

portions were in a cuvette and then each cuvette was measured by the spectrophotometer. Each

specimen culture was shaken (20-60 seconds) on vortex properly before transferring from test

tubes to cuvettes.

Viable Plate Counting Technique

Overnight-grown (12-14 hours) S. Aureus and K. pneumoniae in TSB (Tryptic soy broth) were

diluted in sterile water until the turbidity of the culture was between 3 and 4 McFarland

standards, providing a concentration of approximately 109 CFU/mL. Then the serial dilution of

the cultures was done as follows in 3 steps [CFU/mL values are approximate] —

1. 99 mL Water + 1 mL of 109 CFU/mL 107 CFU/mL

108

2. 99 mL water + 1 mL of 107 CFU/mL 105 CFU/mL

3. 99 mL water + 1 mL of 105 CFU/mL 103 CFU/mL

Then 0.1 g of fiber or fabric specimen from each sample were taken in separate sterile test tubes,

and 10 mL of 103 CFU/mL culture was added. Test tubes were incubated for 1 h, and 18-24 h

before plating. Tryptic Soy Agar (TSA) plate 15 × 100 𝑚𝑚 monoplate from Hardy Diagnostics

was used for this study. A micro-pipetter was used to collect 100 μL (0.1 mL) of solution from

each test tube, shaking it well, and then placing it on 3 TSA plates (triplicate), followed by

spreading the sample uniformly by inoculating loops. One pipetter tip and an inoculating loop

were used for each specimen and then they were disposed of in germicidal disinfectant (Lophene

solution). A vortex mixer was used for shaking 20-60 seconds before transferring each specimen

culture from one container to another or before plating. Incubation of the TSA plates was done

for 20-24 h and 60 h at 37 °C. After incubating, photographs of each plate were taken to count

the number of bacterial colonies in a computer. The used TSA plates were refrigerated before

disposing and destroying the bacteria. The percentage reduction of bacteria was calculated for

antibacterial activity assessment by using equation (2).

% 𝑅 =(𝑁𝑐𝑜𝑛𝑡𝑟𝑜𝑙 − 𝑁𝑠𝑎𝑚𝑝𝑙𝑒)

𝑁𝑐𝑜𝑛𝑡𝑟𝑜𝑙× 100% … … … … (2)

Here, %R = % Reduction of bacterial colony, 𝑁𝑐𝑜𝑛𝑡𝑟𝑜𝑙 = Number of the bacterial colony on the

control plate, 𝑁𝑠𝑎𝑚𝑝𝑙𝑒 = Number of the bacterial colony on sample inoculated plate. The

percentage reduction of bacteria was also calculated as mentioned in equation (1) as was

standardly done in other studies (Manickam & Thilagavathi, 2015; Mishra et al., 2012; Ren et

al., 2017; Xi et al., 2013; Zhang et al., 2003).

109

5.4 Results and Discussions

5.4.1 Assessment by Spectrophotometric technique

This technique was not effective because the antibacterial activity or inhibition to bacterial

growth of the samples was very low. As a result, the differences in the OD readings were very

small. In most of the cases, the values of OD were found to be the same when measuring before

or after inoculation followed by incubation. In most cases, the percentage of bacterial reduction

was incorrectly determined. For example, though “Yala’ showed very good antibacterial activity

against both bacteria in later experiments, it was found to be very poor by this technique (Table

19). It was especially difficult to assess %R of NBFs samples when antibacterial activity is not

very high. Observations suggested that the size of the fiber/fabric specimen was not clearly

influential on the results (Table 19). This was later confirmed by the viable plate counting

method.

Table 19

Percentage reduction of the optical density (OD) of different sample inoculated bacterial

solutions after incubation of 24 h at 37°C

Sample Size Sterilized K. pneumoniae S. aureus

OD %R OD %R

Control - - 0.816 0.00 0.877 0.00

100% Bamboo Viscose

Larger yes 1.131 -38.60 1.025 -16.88

Smaller yes 1.075 -31.74 1.112 -26.80

Larger no 0.836 -2.45 1.064 -21.32

Smaller no 1.106 -35.54 1.060 -20.87

Yala (100% bamboo viscose)

Larger yes 0.781 4.29 0.910 -3.76

Smaller yes 0.821 -0.61 0.815 7.07

Larger no 0.889 -8.95 0.794 9.46

Smaller no 0.698 14.46 0.819 6.61

Raw Red Margin

Mixed yes 1.291 -58.21 1.232 -40.48

no 1.297 -58.95 1.106 -26.11

110

5.4.2 Assessment by Viable Plate Counting Technique

The test with K. pneumoniae was found to work in the direct plate counting technique where the

sample-inoculated bacterial culture was shaken and incubated for 20-24 hours. The growth of

colonies was evident but with a lower number of colonies. On the other hand, there was no

colony in the case of S. aureus. Probably, the S. aureus bacteria were already dead and

ineffective before they were plated after a 20-24-h incubation of sample-inoculated culture. So,

there was no bacterial growth on any of the TSA plates (including control plate). This technique

was repeated 3 times to confirm the result were consistent but still, no growth of S. aureus was

evident. A probable reason is that the bacteria were dead in the water-diluted culture as there was

not enough food for them for a long period of time. So, a shorter time (1 h) of shaking and

incubation of sample-inoculated culture was considered before plating on TSA plates.

After shaking and incubating of sample-inoculated bacterial culture for 1 hour, both of

the bacteria worked well in this technique. The number of colonies on the controlled TSA plates

after 20-24 hours of incubation was achieved within 80-150. So, by plating cultures of S. aureus

and K. pneumoniae after inoculating with different samples, the resulted bacterial colonies were

usable for counting and the calculation of reduction of bacterial growth (%R). The results were

pretty consistent and comparable. Since existing standard test methods are mainly suitable for

fabrics or require fabric-like (strip) sample preparation and results are only comparable for

textiles with a high degree of antibacterial activity, this method will be suitable for even a sample

with very low antibacterial activity and in any form (fiber, yarn, fabric or other forms). The

natural bamboo fibers, produced in eco-friendly ways, seem to have a certain degree of

antibacterial activity, that can provide some protection against bacteria naturally. Some fibers

may not have very high natural antibacterial activity but they are at least useful for a certain

111

degree of protection that comes without any additional cost. The assessment by employing some

existing test methods may estimate a result of zero or no antibacterial activity of textiles with low

antibacterial activity as they need either clear inhibition zones or a substantial change in the

concentration of bacterial culture. Thus, this method will be applicable for identifying the

antibacterial activity in a sample if any.

Another finding of this research is that though it is mainly recommended to test

antibacterial activity of textile materials without sterilization, it may sometime be biased when

raw materials or untreated natural fibers are tested. It was found that there were numerous

unexpected bacterial colonies on TSA plates when raw cotton fibers directly collected from

cotton-balls or raw bamboo samples exposed to damp weather for few days were used for

antibacterial tests (Figure 20a, 20c, 20e, 20g). But unexpected growth was not observed when

(a) Non-sterilized BS, KP (b) Sterilized BS, KP (c) Non-sterilized BS, SA (d) Sterilized BS, SA

(e) Non-sterile. RCF, KP (f) Sterilized RCF, KP (g) Non-sterile. RCF, SA (h) Sterilized RCF, SA

Figure 20. Unexpected bacterial growth on TSA plates inoculated with raw Bissetii bamboo

(BS) and raw cotton fibers (RCF) when samples were non-sterilized and exposed to the

environment vs. bacterial growth by sterilized samples [KP = K. pneumoniae; SA = S. aureus].

112

sterilization was done to the samples before they were added to the broth (Figure 20b, 20d, 20f,

20h). Since K. pneumoniae grows faster than many types of bacteria, they might be possible to

separate in some cases (Figure 20a). Smaller size bacteria like S. aureus is almost impossible to

separate (Figure 20c). It was also observed that %R of the bacteria was almost the same for

sterilized and non-sterilized materials (Table 20).

(a) Control, SA, 24 h (b) G-21, SA, 24 h (c) M-25, SA, 24 h (d) R-27, SA, 24 h

(e) Control, SA, 60 h (f) G-21, SA, 60 h (g) M-25, SA, 60 h (h) R-27, SA, 60 h

Figure 21. Sizes of the bacterial colony of S. aureus inoculated with natural bamboo fibers

(NBFs) after 24 h vs 60 h with almost unchanged counts. [SA = S. aureus; G-21, M-25, and R-

27 are NBFs from Giant gray, Moso, and Red Margin bamboo species respectively.]

Another issue was counting bacterial colonies when the size of the colony is very small

and hard to recognize. This happens when test bacteria grow very slow like S. aureus even after

24 hours. In such a case, counting may be incorrect when there are overlapping or too many

bacteria. Therefore, two observations were made for S. aureus bacteria: one was after 24 h and

another was after 60 hours (Figure 21). It was difficult to count K. pneumoniae after 60 hours as

the colonies overlapped. However, the number of the bacterial colonies after 24 h and 60 h were

113

almost the same for S. aureus and it was easy to see and count them after 60 hours as shown in

Figure 21. So, the incubation can be allowed for a longer time for slow-growing bacteria when a

viable plate counting technique is employed.

5.4.3 Antibacterial Property of Bamboo, NBF and Bamboo Viscose

Out of 11 bamboo viscose textiles, only one sample (Yala) exhibited antibacterial activity against

both bacteria by at least 80% reduction of bacteria. Some of the samples showed nominal

inhibition against one or both bacteria. However, most of the bamboo viscose products did not

show any reduction of bacteria (Table 20). Similar behaviors were also observed for regular

rayon and cotton fiber/fabric. BV and AR were other 100% bamboo viscose textiles showed

(35% and 43%) bacterial reduction against K. pneumoniae when non-sterilized samples were

tested but sterilized samples did not show such activity. Otherwise, almost all other samples

exhibited a similar percentage reduction of bacteria in both sterilized and non-sterilized cases. It

Table 20

Percentage reduction of bacteria by different commercial textile products

Non-sterilized Sterilized Non-sterilized Sterilized

Control 0.00 0.00 0.00 0.00

RT -12.70 12.35 2.70 -12.32

BV 20.63 -13.58 35.14 -2.17

AR 4.76 2.06 43.24 7.25

Yala 90.48 80.25 100.00 98.55

BSA -19.05 14.81 -51.35 -27.54

BB -7.94 5.76 -10.81 -40.58

BBB -11.11 16.46 5.41 -44.20

Cari -4.76 -2.47 -64.86 -44.57

FD -7.94 7.00 -43.24 -50.36

FF -9.52 5.76 -10.81 6.30

GA 6.35 15.23 10.81 -43.12

NCC -14.29 4.94 -27.03 -33.70

Piko 4.76 -4.12 5.41 -25.00

UCF -17.53 9.53 -46.38 9.80

RCF 11.11 -5.10 -75.68 -16.73

BCF 30.16 17.35 37.84 11.84

% Reduction, S. aureus % Reduction, K. pneumoniaeSample

114

was observed that some sterilized materials showed a slight reduction of S. aureus growth (Table

20). Since there might be an unequal number of bacteria in plating due to a slight difference in

concentration of CFU/mL from sample to sample test tubes, %R with a smaller difference

bypositive or negative numbers may not be indicative of inhibition against or support of a

bacterium. As we can see in Figure 22a, 22d, 22e, and 22h, Yala, a commercial apparel

specimen, had antibacterial activity and reduced bacterial growth significantly for both bacteria

as compared with the control. But %R of both bacteria by 100% bamboo viscose was not

noticeable and was lower than even mildly bleached cotton fibers, BCF (Table 20). The BCF

was prepared from raw cotton fiber (RCF) by treating with 4 mL/L Conscour GSRM (scouring

agent), 4 mL/L Consobleach CIL (bleaching agent) and 5 mL/L Consamine JDA (penetrating

agent) at 90 °C for 1 h following by washing and drying.

(a) Control, KP, 24 h (b) BV, KP, 24 h (c) BCF, KP, 24 h (d) Yala, KP, 24 h

(e) Control, SA, 60 h (f) BV, SA, 60 h (g) BCF, SA, 60 h (h) Yala, SA, 60 h

Figure 22. Growth of the bacterial colony on TSA plates inoculated with different samples. [KP

= K. pneumoniae; SA = S. aureus; BV = 100% Bamboo viscose; BCF = mildly bleached cotton

fibers; Yala = 100% bamboo viscose apparel.]

115

As indicated from previous studies discussed earlier, bamboo has some compound that is

responsible for showing antibacterial activity against some bacteria. This study also found

bacterial inhibition by bamboo species and NBFs in most of the cases but the degree of such

activity was not high for all samples (Table 21). Some samples had higher % reduction of

bacteria by sterilized specimens. Probably, unexpected non-cultured environmental bacteria

Table 21

Percentage reduction of bacteria by four bamboo species and their natural fibers

influenced non-sterilized samples tests as indicated by the previous study (Rocky & Thompson,

2019). It was also noticeable that most of the sterilized NBFs exhibited bacterial inhibition and

% reduction of bacteria against K. pneumoniae was more than 50% by most of the samples

(Table 21, Figure 23). Results indicated that Giant Gray and Moso bamboo showed higher

bacterial inhibition against K. pneumoniae bacteria when samples were tested after sterilization.

Such results were stated in other studies (Nirmala et al., 2014). This was opposed to some studies

that bamboo and its extracts showed less antibacterial property against gram-negative bacteria

such as Escherichia coli (E. coli) (Tanaka et al., 2013). However, this study was not with E. coli

Non-sterilized Sterilized Non-sterilized Sterilized

Control 0.00 0.00 0.00 0.00

Bissetii 15.56 -9.55 24.32 52.65

B-16 12.70 -7.14 16.22 55.92

B-23 -1.59 0.00 32.43 61.22

B-25 -9.52 0.00 48.65 66.53

Giant Gray 1.00 19.39 -72.97 61.22

G-21 12.70 3.06 24.32 54.69

G-23 -4.76 10.20 8.11 55.92

G-25 -3.17 15.31 83.78 79.59

Moso 1.59 9.14 -40.54 51.84

M-21 -20.63 4.08 -5.41 53.47

M-22 -6.35 0.00 45.95 56.73

M-25 15.87 22.45 78.38 62.86

Red margin -3.17 8.64 -86.49 -18.37

R-1 -6.35 2.04 -24.32 22.45

R-9 3.17 3.06 32.43 94.69

R-27 49.21 14.29 27.03 -12.65

Sample% Reduction, S. aureus % Reduction, K. pneumoniae

116

as a gram-negative bacterium. So, perhaps, bamboo and NBFs may have lower inhibition against

E. coli.

Many studies have also reported that bamboo and its extracts showed antibacterial

activity against S. aureus (Singh et al., 2010; Tanaka et al., 2011). However, S. aureus bacterial

reduction percentages by raw bamboo specimens and NBFs were lower. In all of the cases, raw

bamboo and NBFs exhibited higher inhibition against K. pneumoniae than that of against S.

aureus (Table 21). There was not a big difference in antibacterial activity among different

bamboo species. Though % reduction of bacterial colonies by different NBFs were not

significantly high, there was an obvious reduction of bacteria by some samples (Figure 23) and

the reduction was higher when fibers were extracted to a certain stage, especially finer or single

fiber stages. It was not clear whether the activity resulted from remnant non-fibrous materials

(a) Control, SA, 60 h (b) B-25, SA, 60 h (c) M-25, SA, 60 h (d) R-9, SA , 60 h

(e) Control, KP, 24 h (f) B-25, KP, 24 h (g) M-25, KP, 24 h (h) R-9, KP, 24 h

Figure 23. Growth of bacterial colony on TSA plates inoculated with different natural bamboo

fiber (NBF) samples [KP = K. pneumoniae; SA = S. aureus; B-25, M-25, and R-9 are NBFs from

Bissetii, Moso, and Red Margin bamboo species respectively].

117

(a) B-23, 10000X (b) M-22, 2000X (c) R-27, 5000X

(d) M-25, 2900X (e) G-23, 1400X (f) R-9, 1700X

Figure 24. Microscopic (SEM) images of natural bamboo fibers (NBFs) from four different

species showing non-fibrous contents responsible for natural properties [Images a—c from

Apreo S and images d—f from Quanta; B = Bissetii; G = Giant Gray; M = Moso; R =Red

Margin].

on extracted NBFs as shown in Figure 24 or from processing chemicals, like NaOH. However,

the SEM images of the fibers with antibacterial property revealed that there was a leftover non-

fibrous material attached to or lying on different NBFs (Figure 24).

Larger negative numbers of % reduction (up to -86%) of bacteria were found for some

raw bamboo samples or NBFs with high non-fibrous contents (Table 21). As presented in Figure

20 that unexpected, environmental or non-test bacterial growth may occur when a material has

bacteria-promoting substances. So, it is crucial to test the antibacterial activity of a material in

both sterilized and non-sterilized conditions.

It is also important that testing antibacterial activity against only two bacteria may not be

enough to assess the property of NBFs as there are more than 650 organisms that can cause

118

disease to the human body (Budama et al., 2013). So, the NBFs may also have effectiveness

against some other disease-causing bacteria and it has not been proven yet.

There is speculation that viscose fibers or regenerated cellulose from bamboo are

antibacterial (Afrin et al., 2014; Mishra et al., 2012; Waite, 2009). But it was reported either

nominal or with no such activity (Hardin et al., 2009; Xi et al., 2013) in tests. The inconsistency

of the antibacterial property by bamboo viscose may raise a question about its authenticity. Since

viscose fibers are extracted cellulose, no natural non-fibrous elements may be retained and such

property may come from processing chemicals or through provided antibacterial treatments or

modifications (Afrin, Tsuzuki, & Wang, 2009; Gokarneshan et al., 2017; Mishra et al., 2012;

Sarkar & Appidi, 2009; Xi et al., 2013; Zheng, Song, Wang, & Wang, 2014).

5.5 Conclusions

To test the antibacterial property of natural fibers or plants, it is important to have suitable

methods that can be conducted appropriately to assess even when the activity is very low. Since

the zone of inhibition technique is not suitable and highly precise for non-fabric specimens, this

study was conducted on spectrophotometric and viable plate counting techniques to assess the

antibacterial property of different types of specimens. Since natural property as bacterial

inhibition is generally not very high and the change in optical density very low, the

spectrophotometric technique was found to not be suitable for such tests. The viable plate

counting was revealed to be very suitable for almost all types of samples such as fabrics, fibers,

and crushed raw bamboo samples. Results were found to be consistent and repeatable if

conducted carefully. Sterilization of the samples before the experiment is recommended as any

contaminating bacteria is eliminated. A longer period of time may be allowed for slow-growing

bacteria for better counting precision.

119

Percentage reduction of bacteria by bamboo viscose textiles was tested where

antibacterial activity was found in only one out of 12 products. This provides an understanding

that antibacterial properties by bamboo viscose may not be a property from the bamboo starting

material, rather it comes from special treatments or through processing chemicals. Without these

additional treatments, products from bamboo viscose would not offer bacterial protection. On the

other hand, microscopic images revealed that there were some non-fibrous elements with natural

bamboo fibers (NBFs) from four bamboo species. All four bamboo species and their NBFs

exhibited antibacterial activity to a certain degree, at least at a low level. The activity was

stronger against K. pneumoniae than against S. aureus. Results also suggested that though raw

bamboo has antibacterial compounds, it may have bacteria-promoting substances at the same

time that caused higher growth of bacteria if non-sterilized samples were tested. The bacterial

inhibition was higher for sterilized bamboo and NBF samples. However, further investigations

are needed to confirm if bamboo species and its NBFs have antibacterial activity and such

activity is not contributed to processing chemicals. Moreover, the antibacterial property of such

materials needs to be tested against other bacteria species.

5.6 References

AATCC 100-2012. (2018). Assessment of Antibacterial Finishes on Textile Materials. Technical

Manual of the American Association of Textile Chemists and Colorists, AATCC. PO Box

12215, Research Triangle Park, N. C. 27709, USA.

AATCC 147-2016. (2018). Antibacterial Activity Assessment of Textile Materials: Parallel

Streak Method. Technical Manual of the American Association of Textile Chemists and

Colorists. PO Box 12215, Research Triangle Park, N. C. 27709, USA.

AATCC 90-2016. (2018). Antibacterial Activity Assessment of Textile Materials: Agar Plate

Method. Technical Manual of the American Association of Textile Chemists and

Colorists, AATCC. PO Box 12215, Research Triangle Park, N. C. 27709, USA.

Abdel-Mohsen, A. M., Hrdina, R., Burgert, L., Abdel-Rahman, R. M., Hašová, M., Šmejkalová,

D., … Aly, A. S. (2013). Antibacterial activity and cell viability of hyaluronan fiber with

silver nanoparticles. Carbohydrate Polymers, 92(2), 1177–1187.

120




1299. https://doi.org/10.1080/00405000.2014.889872

Afrin, T., Tsuzuki, T., Kanwar, R. K., & Wang, X. (2012). The origin of the antibacterial

property of bamboo. Journal of the Textile Institute, 103(8), 844–849.

https://doi.org/10.1080/00405000.2011.614742




(NZ).

ASTM E2149-13a. (2013). Standard Test Method for Determining the Antimicrobial Activity of

Antimicrobial Agents Under Dynamic Contact Conditions. Annual Book of ASTM

Standards. https://doi.org/10.1520/E2149-13A

Bhuiyan, M. A. R., Hossain, M. A., Zakaria, M., Islam, M. N., & Uddin, M. Z. (2017). Chitosan

Coated Cotton Fiber: Physical and Antimicrobial Properties for Apparel Use. Journal of

Polymers and the Environment, 25(2), 334–342. https://doi.org/10.1007/s10924-016-

0815-2

Budama, L., Çakir, B. A., Topel, Ö., & Hoda, N. (2013). A new strategy for producing

antibacterial textile surfaces using silver nanoparticles. Chemical Engineering Journal,

228, 489–495. https://doi.org/10.1016/j.cej.2013.05.018

Burnett-Boothroyd, S. C., & McCarthy, B. J. (2011). Antimicrobial treatments of textiles for

hygiene and infection control applications: An industrial perspective. Textiles for

Hygiene and Infection Control, 196–209.

Chen, J. H., Wang, K., Xu, F., & Sun, R. C. (2015). Effect of hemicellulose removal on the

structural and mechanical properties of regenerated fibers from bamboo. Cellulose, 22(1),

63–72. https://doi.org/10.1007/s10570-014-0488-8

Cheng, X., Ma, K., Li, R., Ren, X., & Huang, T. S. (2014). Antimicrobial coating of modified

chitosan onto cotton fabrics. Applied Surface Science, 309, 138–143.


Chung, Y. S., Lee, K. K., & Kim, J. W. (1998). Durable Press and Antimicrobial Finishing of

Cotton Fabrics with a Citric Acid and Chitosan Treatment. Textile Research Journal,

68(10), 772–775. https://doi.org/10.1177/004051759806801011

Comlekcioglu, N., Aygan, A., Kutlu, M., & Kocabas, Y. Z. (2017). Antimicrobial activities of

some natural dyes and dyed wool Yarn. Iranian Journal of Chemistry and Chemical

Engineering, 36(4), 137–144.

121

Gokarneshan, N., Nagarajan, V., & Viswanath, S. (2017). Developments in Antimicrobial

Textiles – Some Insights on Current Research Trends. Biomedical Journal of Scientific &

Technical Research, 1(1), 230–234. https://doi.org/10.26717/BJSTR.2017.01.000160

Gupta, D., & Bhaumik, S. (2007). Antimicrobial treatments for Textiles. Indian Journal of Fibre

& Textile Research, 32(June), 254–263. Retrieved from

https://www.biocote.com/blog/antimicrobial-treatments-textiles/



Ibrahim, N. A., El-Zairy, W. M., El-Zairy, M. R., Eid, B. M., & Ghazal, H. A. (2011). A smart

approach for enhancing dyeing and functional finishing properties of cotton

cellulose/polyamide-6 fabric blend. Carbohydrate Polymers, 83(3), 1068–1074.


ISO 20645. (2004). Textile fabrics-Determination of antibacterial activity: Agar diffusion plate

test. International Organization for Standardization, ISO. Case postale 56, CH-1211

Geneva 20. Retrieved from http://biblioteca.usac.edu.gt/tesis/08/08_2469_C.pdf

Keski-Saari, S., Ossipov, V., Julkunen-Tiitto, R., Jia, J., Danell, K., Veteli, T., … Niemelä, P.

(2008). Phenolics from the culms of five bamboo species in the Tangjiahe and Wolong

Giant Panda Reserves, Sichuan, China. Biochemical Systematics and Ecology, 36(10),

758–765. https://doi.org/10.1016/j.bse.2008.08.003

Ma, M., Sun, Y., & Sun, G. (2003). Antimicrobial cationic dyes: Part 1: Synthesis and

characterization. Dyes and Pigments, 58(1), 27–35. https://doi.org/10.1016/S0143-

7208(03)00025-1

Manickam, P., & Thilagavathi, G. (2015). A natural fungal extract for improving dyeability and

antibacterial activity of silk fabric. Journal of Industrial Textiles, 44(5), 769–780.

https://doi.org/10.1177/1528083713516662

Mishra, R., Behera, B. K., & Pal, B. P. (2012). Novelty of bamboo fabric. Journal of the Textile

Institute, 103(3), 320–329. https://doi.org/10.1080/00405000.2011.576467

Monticello, R. A., & Askew, P. D. (2013). 20.4 Antimicrobial Textiles and Testing Techniques.

In Adam P. Fraise, Jean-Yves Maillard, & Syed A Sattar (Eds.), Principles and Practice

of Disinfection, Preservation and Sterilization (4th ed., pp. 520–529). Blackwell

Publishing Ltd.

Morais, D. S., Guedes, R. M., & Lopes, M. A. (2016). Antimicrobial approaches for textiles:

From research to market. Materials, 9(6), 498. https://doi.org/10.3390/ma9060498

Nirmala, C., Bisht, M. S., & Laishram, M. (2014). Bioactive compounds in bamboo shoots :

health benefits and prospects for developing functional foods. International Journal of

Food Science & Technology, 49(6), 1425–1431. https://doi.org/10.1111/ijfs.12470

122

Paczosa, M. K., & Mecsas, J. (2007). Klebsiella pneumoniae: Going on the Offense with a

Strong Defense. Hamostaseologie, 27(1), 22–31. https://doi.org/10.1128/MMBR.00078-

15.Address

Patel, B. H., & Tandel, M. G. (2005). Antimicrobial finishing for Textiles: An overview. Asian

Dyer, (May-June), 31–36.

Prusty, A. K., Das, T., Nayak, A., & Das, N. B. (2010). Colourimetric analysis and antimicrobial

study of natural dyes and dyed silk. Journal of Cleaner Production, 18(16–17), 1750–

1756. https://doi.org/10.1016/j.jclepro.2010.06.020

Quitain, A. T., Katoh, S., & Moriyoshi, T. (2004). Isolation of Antimicrobials and Antioxidants

from Moso-Bamboo (Phyllostachys Heterocycla) by Supercritical CO2 Extraction and

Subsequent Hydrothermal Treatment of the Residues. Industrial & Engineering

Chemistry Research, 43, 1056–1060. https://doi.org/10.1021/IE0303552

Ren, Y., Gong, J., Fu, R., Li, Z., Yu, Z., Lou, J., … Zhang, J. (2017). Dyeing and functional

properties of polyester fabric dyed with prodigiosins nanomicelles produced by microbial

fermentation. Journal of Cleaner Production, 148, 375–385.


Rocky, B. P., & Thompson, A. J. (2019). Production of Natural Bamboo Fiber—2: Assessment

and Comparison of Antibacterial Activity. AATCC Journal of Research, 6(5), 1–9.


Sarkar, A. K., & Appidi, S. (2009). Single bath process for imparting antimicrobial activity and

ultraviolet protective property to bamboo viscose fabric. Cellulose, 16(5), 923–928.

https://doi.org/10.1007/s10570-009-9299-8

Schlecht, L. M., Peters, B. M., Krom, B. P., Freiberg, J. A., Hänsch, G. M., Filler, S. G., …

Shirtliff, M. E. (2015). Systemic Staphylococcus aureus infection mediated by Candida

albicans hyphal invasion of mucosal tissue. Microbiology (United Kingdom), 161(1),

168–181. https://doi.org/10.1099/mic.0.083485-0

Shahid, M., Ahmad, A., Yusuf, M., Khan, M. I., Khan, S. A., Manzoor, N., & Mohammad, F.

(2012). Dyeing, fastness and antimicrobial properties of woolen yarns dyed with gallnut

(Quercus infectoria Oliv.) extract. Dyes and Pigments, 95(1), 53–61.

https://doi.org/10.1016/j.dyepig.2012.03.029

Shalini, D., & Anitha, G. (2016). A Review: Antimicrobial Property of Textiles. International

Journal of Science and Research (IJSR), 5(10), 766–768. Retrieved from

https://www.ijsr.net/archive/v5i10/ART20162206.pdf

Shateri Khalil-Abad, M., & Yazdanshenas, M. E. (2010). Superhydrophobic antibacterial cotton

textiles. Journal of Colloid and Interface Science, 351(1), 293–298.

https://doi.org/10.1016/j.jcis.2010.07.049

123

Simoncic, B., & Tomsic, B. (2010). Structures of Novel Antimicrobial Agents for Textiles – A

Review. Textile Research Journal, 80(16), 1721–1737.

https://doi.org/10.1177/0040517510363193

Singh, V., Shukla, R., Satish, V., Kumar, S., Gupta, S., & Mishra, A. (2010). Antibacterial

Activity of Leaves of BAMBOO. International Journal of Pharma and Bio Sciences,

1(2), 1–5.

Tanaka, A., Kim, H. J., Oda, S., Shimizu, K., & Kondo, R. (2011). Antibacterial activity of moso

bamboo shoot skin (Phyllostachys pubescens) against Staphylococcus aureus. Journal of

Wood Science, 57(6), 542–544. https://doi.org/10.1007/s10086-011-1207-9

Tanaka, A., Shimizu, K., & Kondo, R. (2013). Antibacterial compounds from shoot skins of

moso bamboo (Phyllostachys pubescens). Journal of Wood Science, 59(2), 155–159.

https://doi.org/10.1007/s10086-012-1310-6

Tanaka, A., Zhu, Q., Tan, H., Horiba, H., Ohnuki, K., Mori, Y., … Shimizu, K. (2014).

Biological activities and phytochemical profiles of extracts from different parts of

bamboo (phyllostachys pubescens). Molecules, 19(6), 8238–8260.

https://doi.org/10.3390/molecules19068238

TAPPI T205 sp-02. (2006). Forming handsheets for physical tests of pulp. Technical Association

of the Pulp and Paper Industry. 15 Technology Parkway South, Suite 115 Peachtree

Corners, GA 30092.

Vading, M., Nauclér, P., Kalin, M., & Giske, C. G. (2018). Invasive infection caused by

Klebsiella pneumoniae is a disease affecting patients with high comorbidity and

associated with high long-term mortality. PLoS ONE, 13(4), 1–13.

https://doi.org/10.1371/journal.pone.0195258

Vroman, I., & Tighzert, L. (2009). Biodegradable Polymers. Materials, 2, 307–344.

https://doi.org/10.3390/ma2020307



Williams, J. F., Suess, J. C., Cooper, M. M., Santiago, J. I., Chen, T.-Y., Mackenzie, C. D., &

Fleiger, C. (2006). Antimicrobial Functionality of Healthcare Textiles: Current needs,

Options, and Characterization of N halamine-Based Finishes. Research Journal of Textile

and Apparel, 10(4), 1–12. https://doi.org/10.1108/rjta-10-04-2006-b001



6509.

Xue, C. H., Chen, J., Yin, W., Jia, S. T., & Ma, J. Z. (2012). Superhydrophobic conductive

textiles with antibacterial property by coating fibers with silver nanoparticles. Applied

Surface Science, 258(7), 2468–2472. https://doi.org/10.1016/j.apsusc.2011.10.074

124

Zhang, Z., Chen, L., Ji, J., Huang, Y., & Chen, D. (2003). Antibacterial Properties of Cotton

Fabrics Treated with Chitosan. Textile Research Journal, 73(12), 1103–1106.

https://doi.org/10.1177/004051750307301213

Zheng, J., Song, F., Wang, X. L., & Wang, Y. Z. (2014). In-situ synthesis , characterization and

antimicrobial activity of viscose fiber loaded with silver nanoparticles. Cellulose, 21(4),

3097–3105. https://doi.org/10.1007/s10570-014-0324-1

Zupin, Z., & Dimitrovski, K. (2010). Mechanical Properties of Fabrics Made from Cotton and

Biodegradable Yarns Bamboo, SPF, PLA in Weft. Woven Fabric Engineering, 25–46.

https://doi.org/10.5772/10479

----------------------۞-----------------------

125

CHAPTER 6. CONCLUSIONS

The focus of this proposed research was to investigate and model a systematic-achievable

production process of natural bamboo fibers, examination and characterization of the properties

of the fibers in terms of physical, mechanical, chemical, crystallographic, and antibacterial

properties. The extraction processes included production and modification of the natural bamboo

fibers, blending with cotton fibers, carding-combing for sliver preparation, and spinning the

fibers into yarns. The production of the fibers included the well-known bamboo species such as

Bissetii (Phyllostachys Bissetii), Giant Gray (Phyllostachys nigra 'henon'), Moso (Phyllostachys

edulis/ pubescens) and Red Margin (Phyllostachys rubromarginata). The investigation on

expected NBF extraction was successfully attained through different routes. The usage of the

total amount of NaOH (6-38 g/L) in different routes and NBF yield percentages in each route are

reported to assess financial viability. The assessment and identification of the physical and

mechanical properties included dimensions of the fibers such as average length and diameter,

fineness, moisture content, tenacity, elongation, incineration behavior, and solubility. This

dissertation also includes reports on chemical composition, functional groups, behaviors and

crystallographic data on bamboo plants and NBFs that were not determined and not available in

prior literature. Designing and examining a suitable technique, a detailed investigation of the

antibacterial properties, as well as the degree of the activity of the four bamboo plants, natural

bamboo fibers, and 15 commercial textiles, was conducted.

By using 21 formulas with different chemicals and concentrations, 36 different routes

were followed to extract 144 types of NBF samples from four bamboo species. It was observed

126

that at least 47 NBF specimens had good prospects to promote for different uses, especially

fibers for textiles and composites. Different properties of selected NBFs were assessed and

compared with selected conventional fibers. A few sets of NBFs were blended with raw cotton

fibers and spun into yarns. Moisture regain (%) and moisture content (%) of NBFs were found to

be around 8% and 7.5% respectively which was lower than bamboo viscose (10.71% and 9.67%)

or regular rayon (10.83% and 9.77%) but higher than cotton fibers (6.0-6.5% and 5.0-6.0%) and

polyester fibers (0.82% and 0.81%). Incineration properties of different raw bamboo samples and

NBFs were investigated by the standard burning test method. Though some incineration

behaviors were similar to cotton, most of the behaviors were found to be distinctive to some

degree. Similarly, solubility tests also revealed that bamboo biomass and NBFs have almost the

same solubility but they have different appearance in colors and residues in the solutions.

Microscopic examination was employed with scanning electron microscope (SEM) to inspect

surface morphology of the raw bamboo specimens and NBFs. The diameter of the NBFs in terms

of the single fibers was measured which was found to have an average of 10-13 μm and the

range was between 4-22 μm. Yield percentages of the selected fibers were between 40-77%. The

average length of the fibers varied with the routes. The NBF with the highest average length was

extracted from Red Margin bamboo which was 33-37 cm. The extracted NBFs from the other

bamboo species were shorter but within the average spinnable length 1.5-10 cm. The fineness, in

terms of linear density, of the NBFs was 9.68—93.3 Tex and were found to be higher than cotton

fibers. However, none of these fibers were processed or modified with precise machines which

could produce finer fibers. The tensile properties of the spun yarns and some longer fibers were

tested. While the longer but coarser NBFs showed a very high breaking tenacity of 60-140 N/Tex

and a lower breaking elongation of 2.06-2.46%, the NBF yarns of shorter and finer fibers

127

blended with cotton showed a very low breaking tenacity of 1.50-2.50 N/Tex and a higher

breaking elongation of 8.5-11.0%.

The investigation on the characterization of the bamboo plants and NBFs revealed

information that is not previously identified or published. The energy-dispersive X-ray

spectroscopic (EDS) and the X-ray photoelectron spectroscopy (XPS) were used to determine the

elemental composition of bamboo as 70-72% carbon (C) and 28-30% oxygen (O) in EDS and

76-78% C and oxygen 20-24% O in XPS by atomic %. The O/C ratio was found to be 0.26-0.33

for bamboo plants and 0.40-0.70 for NBFs. The major peaks C 1s and O 1s were analyzed to

describe their components which revealed some common chemical bonds and functional groups

such as C-C, C-H, C-O, C=O, O-C-O, and O-C=O. Chemical analyses by using ATR-FTIR

(Attenuated Total Reflectance Fourier Transform Infra-Red) and Raman spectroscopy (RS) were

unveiled important information about bamboo and its fiber. A list of all possible peaks and their

definitions are documented for bamboo plants, NBFs, cotton, rayon, and bamboo viscose fibers.

The importance and differences among spectra of FTIR and Raman spectroscopies of different

materials were assessed. It was found that there were some differences in the peaks and chemical

groups, bonds or behaviors. Specifically, some peaks were found in the spectra of bamboo plants

and NBFs that were not detected in either cotton, rayon or bamboo viscose. This infers that there

may be some unique properties by such chemical properties of bamboo and its fibers that may

not be present in other investigated conventional fibers.

The study of crystallographic properties also revealed some very useful information that

will advance the knowledge about different bamboo plants and their NBFs. The assessment with

X-ray diffraction (XRD) technique using cobalt X-ray source (Co K) was able to identify

crystallinity indexes (CIs), diffraction angles (2θ), lattice planes (hkl), crystallite dimensions and

128

interplanar spacings. The CIs of bamboo plants (61-67%) and NBFs (69-73%) were higher than

both rayon (40%) and bamboo viscose (35-38%) fibers but lower than cotton fibers (76-79%).

These results suggest how different properties such as strength, elasticity, toughness, brittleness,

stiffness, rigidity, chemical resistance, absorption, melting temperature, density, optical and

dyeing property of NBFs will be. The investigation identified four peaks on (101), (101̅), (002)

and (040) lattice planes at 17.0-18.6°, 18.5-19.4°, 25.5°, and 40.5° respectively in all samples

where the peak on (002) corresponded to the most intense peak. The crystallite size of the

bamboo plants and NBFs was determined as 35-39 Å (3.5-3.9 nm).

The development of an assessment of antibacterial activity was very critical to measure

non-fabric materials. This study examined different techniques and modeled a method that was

effective to quantify the antibacterial activity of all kinds of specimens. The reassessment of the

techniques several times proved to be consistent to determine the percentage reduction of

bacteria by the specimens. The effects of different conditions and preparation samples, such as

non-sterilization and without sterilization, were also assessed. The antibacterial tests revealed

that bamboo plants and NBFs had a different degree of inhibition against Staphylococcus aureus

(3-50%) and Klebsiella pneumoniae (8-95%) bacteria. However, except for one product, all 12

bamboo viscose products failed to exhibit bacterial reduction.

This study provides a list of routes for NBF extraction from four bamboo species by

using different chemicals and ingredients, results on different physical, mechanical, chemical and

structural properties, and a detailed assessment of antibacterial activity test methods along with

the antibacterial property of different samples. Thus, the results of this study will be valuable to

execute and continue further research on exploring NBF extraction for textiles.

129

REFERENCES

13-cv-00002-TFH. (2013). Stipulated Judgment and Order for Civil Penalties and Injunctive and

Other Relief, January 3, 2013 Case 1: 13-cv-00002-TFH.

15-cv-02130-APM. (2015). Stipulated Judgment and Order for Civil Penalties and Injunctive and

Other Relief, December 10, 2015 Case 1: 15-cv-02130-APM.

Abdul Khalil, H. P. S., Bhat, I. U. H., Jawaid, M., Zaidon, A., Hermawan, D., Hadi, Y. S., …

Hadi, Y. S. (2012). Bamboo fibre reinforced biocomposites: A review. Materials and

Design, 42, 353–368. https://doi.org/10.1016/j.matdes.2012.06.015



1299. https://doi.org/10.1080/00405000.2014.889872

Afrin, T., Tsuzuki, T., Kanwar, R. K., & Wang, X. (2012). The origin of the antibacterial

property of bamboo. Journal of the Textile Institute, 103(8), 844–849.

https://doi.org/10.1080/00405000.2011.614742




(NZ).

Bambrotex. (2007). Bamboo fiber from Bambrotex. Retrieved January 25, 2017, from

http://www.bambrotex.com/

Batalha, L. A. R., Colodette, J. L., Gomide, J. L., Barbosa, L. C., Maltha, C. R., & Gomes, F. J.

B. (2011). Dissolving pulp production from bamboo. BioResources, 7(1), 640–651.

Biswas, S., Shahinur, S., Hasan, M., & Ahsan, Q. (2015). Physical, Mechanical and Thermal

Properties of Jute and Bamboo Fiber Reinforced Unidirectional Epoxy Composites.

Procedia Engineering, 105(Icte 2014), 933–939.

https://doi.org/10.1016/j.proeng.2015.05.118

ChaoJun, W., ShuFang, Z., ChuanShan, Z., & DaiQi, W. (2014). Improved reactivity of bamboo

dissolving pulp for the viscose process: post-treatment with beating. BioResources,

9(2011), 3449–3455. https://doi.org/10.15376/biores.9.2.3449-3455

Chaowana, P. (2013). Bamboo: An Alternative Raw Material for Wood and Wood-Based

Composites. Journal of Materials Science Research, 2(2), 90–102.

https://doi.org/10.5539/jmsr.v2n2p90

130

Cho, D., Kim, J. M., & Kim, D. (2013). Phenolic resin infiltration and carbonization of cellulose-

based bamboo fibers. Materials Letters, 104, 24–27.

https://doi.org/10.1016/j.matlet.2013.03.132

Correia, V. D. C., Santos, S. F., Mármol, G., Curvelo, A. A. D. S., & Savastano, H. (2014).

Potential of bamboo organosolv pulp as a reinforcing element in fiber-cement materials.

Construction and Building Materials, 72, 65–71.

https://doi.org/10.1016/j.conbuildmat.2014.09.005

Deshpande, A. P., Rao, M. B., & Rao, C. L. (2000). Extraction of Bamboo Fibers and Their Use

as Reinforcement in Polymeric Composites. Journal of Applied Polymer Science, 76, 83–

92.

FTC. (2010a). Four National Retailers Agree to Pay Penalties Labeling Textiles as Made of

Bamboo, While Totaling $1.26 Million for Allegedly Falsely They Actually Were Rayon.

Federal Trade Commission, January 3, 2013. Retrieved from https://www.ftc.gov/news-

events/press-releases/2013/01/four-national-retailers-agree-pay-penalties-totaling-126-

million

FTC. (2010b). FTC Warns 78 Retailers, Including Wal-Mart, Target, and Kmart, to Stop

Labeling and Advertising Rayon Textile Products as “Bamboo.” Federal Trade

Commission, (February 3, 2010). Retrieved from

http://www.ftc.gov/opa/2010/02/bamboo.shtm




Fu, J., Zhang, X., Yu, C., Guebitz, G. M., & Cavaco-Paulo, A. (2012). Bioprocessing of bamboo

materials. Fibres and Textiles in Eastern Europe, 90(90), 13–19.

Fuentes, C. A., Tran, L. Q. N., Dupont-Gillain, C., Vanderlinden, W., De Feyter, S., Van Vuure,

A. W., & Verpoest, I. (2011). Wetting behaviour and surface properties of technical

bamboo fibres. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 380,

89–99. https://doi.org/10.1016/j.colsurfa.2011.02.032

Hanana, S., Elloumi, A., Placet, V., Tounsi, H., Belghith, H., & Bradai, C. (2015). An efficient

enzymatic-based process for the extraction of high-mechanical properties alfa fibres.

Industrial Crops and Products, 70, 190–200.

https://doi.org/10.1016/j.indcrop.2015.03.018



He, J., Cui, S., & Wang, S. (2008). Preparation and Crystalline Analysis of High-Grade Bamboo

Dissolving Pulp for Cellulose Acetate. Journal of Applied Polymer Science, 107(2),

1029–1038. https://doi.org/10.1002/app

131

Jain, S., Kumar, R., & Jindal, U. C. (1992). Mechanical behaviour of bamboo and bamboo

composite. Journal of Materials Science, 27(17), 4598–4604.

https://doi.org/10.1007/BF01165993

Jiang, Z., Miao, J., Yu, Y., & Zhang, L. (2016). Effective preparation of bamboo cellulose fibers

in quaternary ammonium/dmso solvent. BioResources, 11(2), 4536–4549.


Junior, M. G., Teixeira, F. G., & Tonoli, G. H. D. (2018). Effect of the nano-fibrillation of

bamboo pulp on the thermal, structural, mechanical and physical properties of

nanocomposites based on starch/poly(vinyl alcohol) blend. Cellulose, 25(3), 1823–1849.

https://doi.org/10.1007/s10570-018-1691-9

Kim, H., Okubo, K., Fujii, T., & Takemura, K. (2013). Influence of fiber extraction and surface

modification on mechanical properties of green composites with bamboo fiber. Journal of

Adhesion Science and Technology, 27(12), 1348–1358.

Komuraiah, A., Kumar, N., & Prasad, B. (2014). Chemical Composition of Natural Fibers and its

Influence on their Mechanical Properties. Mechanics of Composite Materials, 50(3),

359–376.

Kweon, M. H., Hwang, H. J., & Sung, H. C. (2001). Identification and antioxidant activity of

novel chlorogenic acid derivatives from bamboo (Phyllostachys edulis). Journal of

Agricultural and Food Chemistry, 49(10), 4646–4655. https://doi.org/10.1021/jf010514x

Liu, L., Cheng, L., Huang, L., & Yu, J. (2012). Enzymatic treatment of mechanochemical

modified natural bamboo fibers. Fibers and Polymers, 13(5), 600–605.

https://doi.org/10.1007/s12221-012-0600-3



https://doi.org/10.1007/s12221-011-0095-3

Ma, X., Huang, L., Cao, S., Chen, Y., & Chen, L. (2011). Preparation of bamboo dissolving pulp

for textile production. part 1. study on prehydrolysis of green bamboo for producing

dissolving pulp. BioResources, 6(2), 1428–1439.

McLarren, W. (2010). US Consumer Watchdog Says Shoo to Bamboo Textiles. Retrieved

December 5, 2016, from TreeHugger.com

Michael. (2008). Bamboo Sprouting Green Myths. Retrieved January 9, 2018, from

http://organicclothing.blogs.com/my_weblog/2008/08/bamboo-sprouting-green-

myths.html

Morton. (2005). Extent and characteristics of bamboo resources. World Bamboo Resources – a

Thematic Study Prepared in the Framework of the Global Forest Resources Assessment

2005, 11–30.

132

Muhammad, A., Rahman, M. R., Hamdan, S., & Sanaullah, K. (2019). Recent developments in

bamboo fiber-based composites: a review. Polymer Bulletin (Vol. 76). Springer Berlin

Heidelberg. https://doi.org/10.1007/s00289-018-2493-9



https://doi.org/10.1186/s40691-015-0054-5

Ogawa, K., Hirogaki, T., Aoyama, E., & Imamura, H. (2008). Bamboo Fiber Extraction Method

Using a Machining Center. Journal of Advanced Mechanical Design, Systems, and

Manufacturing, 2(4), 550–559. https://doi.org/10.1299/jamdsm.2.550

Okubo, K., Fujii, T., & Yamamoto, Y. (2004). Development of bamboo-based polymer

composites and their mechanical properties. Composites Part A: Applied Science and

Manufacturing, 35(3), 377–383. https://doi.org/10.1016/j.compositesa.2003.09.017

Parisi, M. L., Fatarella, E., Spinelli, D., Pogni, R., & Basosi, R. (2015). Environmental impact

assessment of an eco-efficient production for coloured textiles. Journal of Cleaner

Production, 108(PartA), 514–524. https://doi.org/10.1016/j.jclepro.2015.06.032

Phong, N. T., Fujii, T., Chuong, B., & Okubo, K. (2012). Study on How to Effectively Extract

Bamboo Fibers from Raw Bamboo and Wastewater Treatment. Journal of Materials

Science Research, 1(1), 144–155. https://doi.org/10.5539/jmsr.v1n1p144

Prasad, A. V. R., & Rao, K. M. (2011). Mechanical properties of natural fibre reinforced

polyester composites: Jowar, sisal and bamboo. Materials and Design, 32(8), 4658–4663.


Rai, V., Ghosh, J. S., Pal, A., & Dey, N. (2011). Identification of genes involved in bamboo fiber

development. Gene, 478(1–2), 19–27. https://doi.org/10.1016/j.gene.2011.01.004

Rao, K. M. M., & Rao, K. M. (2007). Extraction and tensile properties of natural fibers: Vakka,

date and bamboo. Composite Structures, 77(3), 288–295.

https://doi.org/10.1016/j.compstruct.2005.07.023

Rocky, A. B. P. (2017). An experimental study toward eco-friendly bamboo fiber extraction for

textiles. MS Thesis, University of Alabama Libraries. Retrieved from

https://search.proquest.com/openview/fb9c334afe91b04308b8a56ba8797e1c/1?pq-

origsite=gscholar&cbl=18750&diss=y

Shih, Y. (2007). Mechanical and thermal properties of waste water bamboo husk fiber reinforced

epoxy composites. Materials Science and Engineering A, 445–446, 289–295.

https://doi.org/10.1016/j.msea.2006.09.032

Singh, V., Shukla, R., Satish, V., Kumar, S., Gupta, S., & Mishra, A. (2010). Antibacterial

Activity of Leaves of BAMBOO. International Journal of Pharma and Bio Sciences,

1(2), 1–5.

133

Steffen, D., Marin, A. W., & Müggler, I. R. (2013). Bamboo: A holistic approach to a renewable

fibre for textile design. 10th European Academy of Design Conference - Crafting the

Future, 1–14.

Sugesty, S., Kardiansyah, T., & Hardiani, H. (2015). Bamboo as raw materials for dissolving

pulp with environmental friendly technology for rayon fiber. Procedia Chemistry, 17,

194–199. https://doi.org/10.1016/j.proche.2015.12.122

Tanaka, A., Kim, H. J., Oda, S., Shimizu, K., & Kondo, R. (2011). Antibacterial activity of moso

bamboo shoot skin (Phyllostachys pubescens) against Staphylococcus aureus. Journal of

Wood Science, 57(6), 542–544. https://doi.org/10.1007/s10086-011-1207-9

Tanaka, A., Shimizu, K., & Kondo, R. (2013). Antibacterial compounds from shoot skins of

moso bamboo (Phyllostachys pubescens). Journal of Wood Science, 59(2), 155–159.

https://doi.org/10.1007/s10086-012-1310-6

Tanaka, A., Zhu, Q., Tan, H., Horiba, H., Ohnuki, K., Mori, Y., … Shimizu, K. (2014).

Biological activities and phytochemical profiles of extracts from different parts of

bamboo (phyllostachys pubescens). Molecules, 19(6), 8238–8260.

https://doi.org/10.3390/molecules19068238

Tokoro, R., Vu, D. M., Okubo, K., Tanaka, T., Fujii, T., & Fujiura, T. (2008). How to improve

mechanical properties of polylactic acid with bamboo fibers. Journal of Materials

Science, 43(2), 775–787. https://doi.org/10.1007/s10853-007-1994-y

Tran, D. T., Nguyen, D. M., Thuc, C. N. H., & Dang, T. T. (2013). Effect of coupling agents on

the properties of bamboo fiber-reinforced unsaturated polyester resin composites.

Composite Interfaces, 20(5), 343–353.

Trujillo, E., Moesen, M., Osorio, L., Van Vuure, A. W., Ivens, J., & Verpoest, I. (2014). Bamboo

fibres for reinforcement in composite materials: Strength Weibull analysis. Composites

Part A: Applied Science and Manufacturing, 61, 115–125.





properties (Part II). Journal of Textile and Apparel, Technology and Management, 6(3),

1–22. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-


Witayakran, S., Haruthaithanasan, M., Agthong, P., & Thinnapatanukul, T. (2013). Green

Production of Natural Bamboo fibers for Textiles. In 2013 International Textiles and

Costume Congress (Vol. 28-29 Octo, pp. 1–6).



134

6509.

Xie, X., Zhou, Z., Jiang, M., Xu, X., Wang, Z., & Hui, D. (2015). Cellulosic fibers from rice

straw and bamboo used as reinforcement of cement-based composites for remarkably

improving mechanical properties. Composites Part B, 78, 153–161.


Yu, Y. L., Huang, X. A., & Yu, W. J. (2014). High performance of bamboo-based fiber

composites from long bamboo fiber bundles and phenolic resins. Journal of Applied

Polymer Science, 131(12), 1–8. https://doi.org/10.1002/app.40371

Yu, Y., Wang, H., & Lu, F. (2014). Bamboo fibers for composite applications: a mechanical and

morphological investigation. Journal of Materials Science, 49(15), 2559–2566.

https://doi.org/10.1007/s10853-013-7951-z



https://doi.org/10.1177/0040517509337633

Zakikhani, P., Zahari, R., Sultan, M. T. H., & Majid, D. L. (2014a). Bamboo Fibre Extraction

and Its Reinforced Polymer Composite Material. International Journal of Chemical,

Molecular, Nuclear, Materials and Metallurgical Engineering, 8(4), 322–325.

Zakikhani, P., Zahari, R., Sultan, M. T. H., & Majid, D. L. (2014b). Extraction and preparation

of bamboo fibre-reinforced composites. Materials and Design, 63, 820–828.


Zheng, J., Song, F., Wang, X. L., & Wang, Y. Z. (2014). In-situ synthesis , characterization and

antimicrobial activity of viscose fiber loaded with silver nanoparticles. Cellulose, 21(4),

3097–3105. https://doi.org/10.1007/s10570-014-0324-1

Zou, L., Jin, H., Lu, W. Y., & Li, X. (2009). Nanoscale structural and mechanical

characterization of the cell wall of bamboo fiber. Materials Science and Engineering: C,

29(4), 1375–1379. https://doi.org/http://dx.doi.org/10.1016/j.msec.2009.02.007

Zupin, Z., & Dimitrovski, K. (2010). Mechanical Properties of Fabrics Made from Cotton and

Biodegradable Yarns Bamboo, SPF, PLA in Weft. Woven Fabric Engineering, 25–46.

https://doi.org/10.5772/10479

----------------------⁂-----------------------

production, modification, and characterization of …

Documents