preparation and characterization of palm oil based ...umpir.ump.edu.my/12960/1/fkksa - muhammad...

PREPARATION AND CHARACTERIZATION OF PALM OIL BASED

POLYALKYD FILMS AND COMPOSITES WITH MULTI-WALLED

CARBON NANOTUBES

MUHAMMAD REMANUL ISLAM

Thesis submitted in fulfilment of the requirements for the award of the degree of

Doctor of Philosophy in Chemical Engineering

Faculty of Chemical and Natural Resources Engineering

UNIVERSITI MALAYSIA PAHANG

AUGUST 2015

vii

ABSTRACT

In this research, polyalkyd resins were prepared from palm oil by using polycondensation

reaction. A two-step method viz., alcoholysis and esterification was conducted to

synthesize polyalkyd resins. Prior to alcoholysis, crude palm oil was subjected for

dehydration process to increase its unsaturation. Different types of catalysts such as,

sulphuric acid, para-toluene sulfonic acid, phosphoric acid, sodium hydrogen sulphate and

potassium hydrogen sulphate were used for the dehydration. In alcoholysis process, the

triglyceride-based dehydrated oil was reacted with glycerol to produce monoglyceride. The

prepared monoglyceride was further brought into contact with acid anhydride to prepare

polyalkyds. Response surface methodology was used to optimize the reaction parameters

for esterification like reaction temperature, reaction time, catalyst concentration, acid

anhydride to mono-glyceride ratio and agitation speed. The optimum condition was used to

prepare various types of polyalkyds by using different types of acid anhydrides such as,

maleic anhydride, succinic anhydride, phthalic anhydride, 3,4,5,6-tetrahydrophthalic

anhydride and cis-1,2-cyclohexanedicarboxylic anhydride. A comparison was drawn

among the resins prepared by using different types and percentages of acid anhydrides.

The produced bioresins were characterized for physico-chemical properties such as,

viscosity, density, iodine value, acid value, drying time, non-volatile materials content,

specific gravity, colour, etc. The resins prepared with optimum reaction parameters were

subjected for curing process by using methyl ethyl ketone peroxide and cobalt

naphthanate. To enhance the resinous property, multi-walled carbon nanotubes

(MWCNTs) were dispersed into the resin at different percentages of loading such as, 0.5,

1.0 and 1.5 wt.%. The loading was optimized based on the tensile strength of the film.

Finally, in-situ polymerization with carbon nanotubes during esterification was performed

by adding optimum percentage of loading. The films produced from different formulations

were characterized by different testing such as, adhesion, chemical resistivity,

thermogravimetric analysis, differential scanning calorimetry, field-emission scanning

electron microscopy, x-ray diffraction analysis, contact-angle measurement, tensile testing,

pencil hardness, gloss, etc. In addition, the curing kinetics of the resin was analysed to

evaluate the kinetic parameters such as, reaction rate, activation energy and degree of

conversion in terms of time and temperature. Result analyses through RSM revealed a

desirability of 0.985 for the reaction time of 88.64 min. Moreover, 91.5% fractional

conversion was achieved actually, which is close to the predicted value. Analysis revealed

that 3,4,5,6-tetrahydophthalic anhydride-based resin showed improved resinous property

than others due to high degree of crosslinking. It was also found that higher amount of

aliphatic acid anhydrides are responsible for high degree of crosslinking density, whereas

higher thermal stability was ensured by the inclusion of aromatic acid anhydride. Finally,

incorporation of MWCNTs into the alkyd resin enhanced the overall film properties, which

was further improved through in-situ reaction. The physical bonding and mechanical

entanglement were the possible reason for showing improved properties, as revealed from

the analysis.

viii

ABSTRAK

Dalam penyelidikan ini, resin polialkid telah disediakan daripada minyak sawit dengan

menggunakan tindak balas polikondensasi. Satu kaedah yang merangkumi dua langkah,

alkoholisis dan pengesteran telah dijalankan untuk mensintesis resin polialkid. Sebelum

alkoholisis, minyak sawit mentah telah menjalani proses pendehidratan untuk

meningkatkan ketidaktepuannya. Pemangkin yang berbeza seperti asid sulfurik, para-

toluena asid sulfonic, asid fosforik, natrium hidrogen sulfat dan kalium hidrogen sulfat

telah digunakan untuk proses pendehidratan minyak sawit. Dalam proses alkoholisis,

minyak berasaskan trigliserida yang terhidrat telah ditindak balaskan dengan gliserol untuk

menghasilkan monogliserid. Monogliserid yang terhasil terus ditindak balaskan dengan

asid anhidrida untuk menyediakan polialkids. Kaedah gerak balas permukaan digunakan

untuk mengoptimumkan parameter tindak balas pengesteran seperti suhu, masa tindak

balas, kepekatan pemangkin, nisbah asid anhidrida kepada mono-glyceride dan kelajuan

pengacauan. Keadaan optima telah digunakan untuk menyediakan pelbagai jenis alkyds

dengan menggunakan asid anhidrida seperti anhidrida maleic, anhidrida phthalic, anhidrida

succinic, anhidrida 3,4,5,6 - tetrahydrophthalic dan cis - 1,2- cyclohexanedicarboxylic

anhidrida. Perbandingan antara resin juga dilakukan dengan menggunakan jenis dan

peratusan asid anhidrida yang berbeza. Bioresin yang terhasil telah menjalani ujian ciri

fiziko – kimia seperti kelikatan, ketumpatan, nilai iodin, nilai asid, masa pengeringan,

kandungan bahan-bahan yang tidak meruwap, graviti tentu, warna, dan lain-lain. Resin

disediakan daripada tindak balas parameter optimum akan menjalani proses pengawetan

dengan menggunakan metil etil keton peroksida dan kobalt naphthanate. Untuk

meningkatkan ciri resin, nanotiub karbon berbilang berdinding (MWCNTs) akan

disebarkan ke dalam resin mengikut peratusan yang berbeza seperti 0.5, 1.0 dan 1.5 %

berat. Kemasukan pengisi telah dioptimumkan bergantung pada kekuatan tegangan filem tersebut. Akhirnya, pempolimeran in-situ dengan karbon nanotiub melalui proses

esterifikasi dilakukan dengan menambah bahan mengikut peratusan yang optimum. Filem-

filem yang dihasilkan daripada formulasi yang berbeza telah dicirikan oleh ujian yang

berbeza seperti lekatan, kerintangan kimia, analisis termogravimetri, pengkamiran

pengimbasan kalorimeter, bidang - pelepasan imbasan elektron mikroskop, analisis x- ray

pembelauan, pengukuran sentuhan sudut, ujian tegangan, kekerasan pensil, gloss dan lain-

lain. Tambahan pula, kinetik pengawetan resin dianalisis untuk menilai parameter kinetik

seperti kadar tindak balas, tenaga pengaktifan, tahap penukaran dari segi masa dan suhu.

Keputusan analisis melalui RSM mendedahkan 0.985 didapati dengan tindak balas masa

88.64 min. Selain itu, 91.5 % penukaran yang dicapai menunjukkan data direkod

berhampiran dengan nilai yang diramalkan. Analisis menunjukkan bahawa resin

berasaskan anhidrida 3,4,5,6 - tetrahydophthalic menunjukkan peningkatan ciri resin

daripada yang lain kerana darjah sambung-silang yang tinggi. Ia juga menunjukkan

bahawa peningkatan kuantiti anhidrida alifatik bertanggungjawab bagi peningkatan darjah

ketumpatan Sambung-silang, manakala kestabilan haba yang lebih tinggi dipastikan oleh

kemasukan asid anhidrida aromatik. Akhir sekali, penggabungan MWCNTs ke dalam resin

alkyd yang optimum dipertingkatkan ciri-ciri keseluruhan resin, dengan peningkatan

ketara melalui tindak balas in-situ. Ikatan fizikal dan penyangkutan mekanikal adalah

sebab yang mungkin untuk menunjukkan sifat-sifat baik, seperti yang dinyatakan daripada

analisis.

ix

TABLE OF CONTENTS

Page No

TITLE PAGE i

STATEMENT OF AWARD FOR DEGREE ii

SUPERVISOR’S DECLARATION iii

STUDENT’S DECLARATION iv

DEDICATION v

ACKNOWLEDGEMNTS vi

ABSTRACT vii

ABSTRACK viii

TABLE OF CONTENTS ix

LISTS OF TABLES xiv

LIST OF SCHEMES xvi

LIST OF FIGURES xvii

LIST OF SYMBOLS xx

LIST OF ABBREVIATIONS xxii

CHAPTER 1 INTRODUCTION 01

1.1 BACKGROUND 01

1.2 PROBLEM STATEMENT 05

1.3 OBJECTIVES 06

1.4 SCOPE 07

1.5 RATIONAL OF THE RESEARCH 07

x

CHAPTER 2 LITERATURE REVIEW 09

2.1 INTRODUCTION 09

2.2 VEGETABLE OILS AND THEIR PROPERTIES 10

2.3 POLYMERS FROM VEGETABLE OILS 19

2.3.1 Polyesters 22

2.3.1.1 Optimization process of reaction parameters 27

2.3.1.2 Polymerization reactions and techniques 29

2.3.1.3 Polycondensation reaction 29

2.3.2 Other Polymers 30

2.3.2.1 Oxidative and thermo-oxidative polymers 30

2.3.2.2 Polyurethanes 32

2.3.2.3 Polyester amides 36

2.3.2.4 Vinyl polymers 40

2.3.2.5 Epoxies 42

2.3.2.6 Polyamides 43

2.3.2.7 Metathesis of oils 44

2.4 CURING PROCESS AND CURING KINETICS 45

2.4.1 Dynamic Methods 50

2.4.2 Isothermal Methods 53

2.5 NANO PARTICLE INCORPORATION 54

2.6 CHALLANGES AND DIFFICULTIES 56

2.7 CURRENT CONDITION OF PETROLEUM BASED

RESOURCES

58

2.8 SUMMARY 59

CHAPTER 3 MATERIALS AND METHODS 60

3.1 INTRODUCTION 60

3.2 MATERIALS 62

xi

3.3 METHODS 64

3.3.1 Dehydration of Oil 64

3.3.2 Oil Characterization 65

3.3.2.1 Acid value 65

3.3.2.2 Iodine value 66

3.3.2.3 Density 67

3.3.2.4 Viscosity 67

3.3.2.5 Fourier transform of infrared (FTIR) spectroscopy 67

3.3.2.6 Nuclear magnetic resonance (NMR) spectroscopy 68

3.3.3 Resin Preparation and Characterization 68

3.3.3.1 Preparation of bio resin 68

3.3.3.2 Optimisation of esterification process 70

3.3.3.3 Curing process of resin 73

3.3.3.4 Curing kinetics analysis 74

3.3.3.5 Non-volatile materials content 78

3.3.3.6 Molecular weight and Polydispersity index 78

3.3.4 Film Preparation and Characterization 79

3.3.4.1 Nano composite film preparation 79

3.3.4.2 Scanning electron microscopy 79

3.3.4.3 Thermogravimetric analysis 79

3.3.4.4 Differential scanning calorimetry 80

3.3.4.5 X-ray diffraction (XRD) 80

3.3.4.6 Tensile properties 81

3.3.4.7 Gel fraction 81

3.3.4.8 Swelling ratio 81

3.3.4.9 Crosslinking density 82

3.3.4.10 Chemical resistivity 82

3.3.4.11 Gloss 82

3.3.4.12 Adhesion 83

3.3.4.13 Solubility 83

3.3.4.14 Pencil hardness 84

3.3.4.15 Wettability 85

3.4 SUMMARY 85

xii

CHAPTER 4 RESULTS AND DISCUSSION 86

4.1 INTRODUCTION 86

4.2 ANALYSES OF OIL PROPERTIES 86

4.2.1 Structural Properties 86

4.2.2 Physicochemical Properties: Effects of Dehydration 88

4.3 ANALYSES OF RESIN PROPERTIES: OPTIMIZATION OF

ESTERIFICATION THROUGH RSM

91

4.3.1 Factor Analysis 91

4.3.2 Process Analysis 95

4.3.3 Process Optimization 100

4.3.4 Evaluation of Polymerization Reaction and Technique 102

4.4 ANALYSES OF RESIN PROPERTIES: EFFECTS OF THE

TYPES OF ACID ANHYDRIDES

104

4.4.1 Physicochemical Properties 104


4.4.3 XRD 111

4.4.4 Surface Property 112

4.4.5 Crosslinking Density 116

4.4.6 Solubility 116

4.4.7 Pencil Hardness 117

4.4.8 Thermal Properties 117

4.4.9 Chemical Resistivity 120

4.4.10 Summary 121

4.5 ANALYSES OF RESIN PROPERTIES: EFFECTS OF

ALIPHATIC ACID ANHYDRIDE CONTENT

122

4.5.1 Physicochemical Properties 122

4.5.2 FTIR and 1H NMR 124

4.5.3 Curing Kinetics 128

4.5.4 XRD 132



xiii

4.5.7 Solubility 137




4.5.11 Summary 141

4.6 ANALYSIS THE EFFECTS OF MWCNTS INCORPORATION 143

4.6.1 Tensile Properties 143







4.6.8 Summary 158

CHAPTER 5 CONCLUSION AND RECOMMENDATIONS 159

5.1 CONCLUSION 159

5.2 RECOMMENDATIONS FOR FUTURE WORK 161

REFERENCES 163

APPENDIX A OPTIMIZATION THROUGH RSM 192

APPENDIX B LIST OF PUBLICATIONS 196

xiv

LIST OF TABLES

Table No. Title Page No.

2.1 Annual oil yield per cultivated hectare [kg ha-1

]. 10

2.2 Viscosity, density and iodine value of some common vegetable

oils.

12

2.3 FTIR data for vegetable oils. 13

2.4 Some representative 1H NMR shift values for vegetable oils. 13

2.5 Common fatty acids, structure and formula. 16

2.6 Common vegetable oils and their fatty acid content. 17

3.1 List of chemicals and raw materials used in this research 63

3.2 Different types of acid anhydrides and their properties. 64

3.3 Reaction details of the dehydration process for different catalysts. 65

3.4 Reactants for the alcoholysis process of palm oil. 68

3.5 Experimental factors and pre-assumed range of values for

esterification.

71

3.6 Full factorial central composite design matrix including five

factors for a single response.

72

3.7 Amount of different acid anhydrides for the esterification reaction

for the preparation of polyalkyds.

73

3.8 Mixing details for the esterification reaction for the preparation of

polyalkyds based on different ratios of aromatic and aliphatic acid

anhydrides.

73

3.9 Mixing details of the curing process. 74

3.10 Different gloss categories at 60o 83

4.1 Physicochemical properties of crude and dehydrated oil 89

4.2 Full factorial central composite design matrix including five

factors for a single response.

92

4.3 Analysis of variance for response surface quadratic model. 94

4.4 The solutions suggested by RSM for the esterification process 101

4.5 The optimum solution suggested by RSM 102

4.6 Properties of various types of resins based on different acid

anhydrides

106

xv

4.7 XRD parameters for different types of resins based on different

acid anhydrides.

111

4.8 Gloss, gel content, swelling ratio, crosslinking density and

adhesion properties of different resins prepared from different

acid anhydrides.

114

4.9 Pencil hardness of various types of cured resins based on different

acid anhydrides.

117

4.10 Thermal properties of different resins based on different acid

anhydrides.

118

4.11 Chemical resistivity of various types of resins. 121

4.12 Physicochemical properties of various types of resins based on

aromatic and/or aliphatic acid anhydrides.

124

4.13 Total heat of reactions, onset, peak and final temperatures at

different heating rates.

128

4.14 Kinetic parameters for different heating rates. 132

4.15 XRD parameters for different types of resins. 133


adhesion properties of different resins.

135

4.17 Pencil hardness of various types of cured resins. 138

4.18 Thermal properties of different resins. 140

4.19 Chemical resistivity of the cured resins. 141

4.20 Elongation at break of the films 144

4.21 Pencil hardness of various types of cured resins 146

4.22 XRD parameters for different types of resins. 149


adhesion properties of different resins

150

4.24 Thermal properties of different resins 156

4.25 Chemical resistivity of the cured resins 158

xvi

LIST OF SCHEMES

Scheme No. Title Page No.

2.1 A triglyceride molecule. 14

2.2 Reactions between glycerol and fatty acids to produce

triglyceride.

14

2.3 Various types of fatty acid chains. 15

2.4 Structure of saturated and unsaturated fatty acids available in

palm oil

19

2.5 Triglyceride molecules with various reactive positions. 20

2.6 Various routes of polymerization from plant based oils. 21

2.7 Ester functional group. 22

2.8 Routes of polyester preparation: (a) polycondensation between

diacids and diols and (b) Ring opening polymerization.

23

2.9 Alchoholysis and poly-condensation reaction of oil with acid

anhydride

24

2.10 Preparation of waterborne alkyds 26

2.11 Oxidative polymerization process. 31

2.12 Reaction between di-isocyanate and polyol to form

polyurethane.

33

2.13 An alternating polyester amide. 37

2.14 Synthesis of HELA (a), N-phthaloyl glutamic acid (b), and

PEA (c).

39

2.15 Epoxidation of oleic acid. 42

2.16 Structure of organic polyamide. 43

2.17 Curing reaction during polymerization of divinyl benzene by

using styrene.

46

2.18 Curing process of unsaturated polyesters. 47

2.19 Curing process of epoxy resin. 48

2.20 Schematic images of MWCNTs (a) and SWCNTs (b) 55

3.1 Alcoholysis (I) and esterification reaction (II-VI). 69

4.1 Mechanism for polycondensation reaction between carboxylic

and hydroxyl functional group containing compound.

103

xvii

LIST OF FIGURES

Figure No. Title Page No.

2.1 Applications of vegetable oil-based polymers. 20

3.1 Process flow diagram 61

3.2 Experimental design of the research 62

3.3 Reaction set up for polyalkyd preparation 70

3.4 Scale of pencil hardness testing from softer to harder hardness. 84

4.1 FTIR spectrum of palm oil. 87

4.2 1H NMR spectrum of palm oil. 88

4.3 3-D curves of agitation vs. temperature (a), agitation vs. time (b)

and agitation vs catalyst concentration (c).

97

4.4 3-D curves of catalyst concentration vs. molar ratio (a), catalyst

concentration vs. temperature (b) and catalyst concentration vs

time (c).

98

4.5 3-D curves of molar ratio vs. agitation (a), molar ratio vs.

temperature (b) and molar ratio vs time (c).

99

4.6 3-D curve of time vs. temperature. 100

4.7 FTIR spectra of the resins based on different acid anhydrides. 107

4.8 1H NMR spectrum of SAR. 108

4.9 1H NMR spectrum of MAR. 109

4.10 1H NMR spectrum of PAR. 109

4.11 1H NMR spectrum of TPAR. 110

4.12 1H NMR spectrum of CDAR. 110

4.13 XRD profiles of different films based on different acid

anhydrides.

112

4.14 Contact angle of different acid anhydrides-based films showing

the wettability.

113

4.15 The FE-SEM images of the surfaces of different films prepared

from different resins based on different acid anhydrides.

115

4.16 Weight vs. temperature curves of different resins based on

different acid anhydrides.

119

4.17 Derivative weight vs. temperature curves of different resins 119

xviii

based on different acid anhydrides.

4.18 DSC thermograms of the various resins based on different acid

anhydrides.

120

4.19 FTIR spectra of the resins based on different aromatic and/or

aliphatic acid anhydrides.

125

4.20 1H NMR spectrum of MA0. 126




4.24 Heat flow vs. Temperature curves for different heating rates. 129

4.25 Degree of conversion vs. temperature plot for the curing process

of palm oil based alkyds.

130

4.26 Degree of conversion vs. time plot for the curing process of

palm oil based alkyds.

130

4.27 Reaction rate vs. temperature curve for the curing process of

palm oil based alkyds.

131

4.28 Reaction rate vs. Time plot for the curing process of palm oil

based alkyds.

131

4.29 XRD profiles of different resins based on aromatic or/and

aliphatic acid anhydrides.

133

4.30 Contact angles of different films. 134

4.31 FE-SEM images of different films. 136

4.32 Weight vs. temperature curves of different resins. 139

4.33 Derivative weight vs. temperature curves of different resins. 139

4.34 DSC thermograms of the cured films. 140

4.35 Tensile strength (MPa) and tensile modulus (MPa) of different

films.

145

4.36 FTIR spectra of different films prepared without MWCNTs,

with MWCNTs (at different loading) and in-situ reacted

MWCNTs.

147

4.37 XRD defractograms of different polymeric films prepared

without MWCNTs, with MWCNTs (at different loading) and in-

situ reacted MWCNTs.

148

xix

4.38 Contact angles of different polymeric films based on without

MWCNTs and with MWCNTS.

150

4.39 Surface morphology of polyalkyd and different percentages of

MWCNTs filled polyalkyds films.

152

4.40 Weight vs. temperature curves of different films prepared

without MWCNTs, with MWCNTs (at different loading) and in-

situ reacted MWCNTs.

154

4.41 Derivative weight vs. temperature curves of different films

produced without MWCNTs, with MWCNTs (at different

loading) and in-situ reacted MWCNTs.

155

4.42 DSC thermograms of different films prepared without

MWCNTs, with MWCNTs (at different loading) and in-situ

reacted MWCNTs.

156

xx

LIST OF SYMBOLS

A Pre-exponential factor or Arrhenius factor

α Degree of cure

σt Tensile strength (MPa)

β Heating rate (0C/min)

βo Unknown coefficient in RSM analysis

Βi Unknown coefficient in RSM analysis

Βij Unknown coefficient in RSM analysis

d Interplaner spacing

dα/dt Reaction rate

δij Unknown coefficient in RSM analysis

ε Random error of experimentation

η* Complex viscosity

θ Bragg scattering angle

Ea Activation energy (J mol-1

)

ΔH Heat of fusion of sample

ΔHm Heat of fusion of 100% crystalline reference material

HR Total heat of reaction

ΔHR Heat of reaction

dH/dt Normalized heat generated per unit time

ΔHt Released heat per unit of mass up to the time, t

IDSC Degree of crystallinity (%)

k Rate constant

K Scherer’s constant

m The order of reaction

n The order of reaction

Mn Number average molecular weight

Mw Weight average molecular weight

R Gas constant

Tg Glass transition temperature (0C)

Tm Melting temperature (0C)

Tc Crystallization temperature (0C)

xxi

Tmax Temperature of maximum reaction rate (0C)

x Reaction order

xi Matrix of the un-coded process variables

xj Matrix of the un-coded process variables

Y Fractional conversion

Yn Fractional conversion

λ X-ray wavelength

Z Frequency factor

xxii

LIST OF ABBREVIATIONS

ANOVA Analysis of variance

ASTM American standard testing method

AV Acid value

BPH N-benzyl pyrazinium hexafluoroantimonate

CN Carbon number

CFA Cottonseed oil fatty amide

CNT Carbon nano tube

CPEA Cotton seed oil based polyester amide

DA Dimer acid

DB Double bond

DCC Dicyclohexylcarbodiimide

DDA Dicyandiamide

DEA Diethanolamine

DES Design expert software

DGEBA Diglycidyl ether of bisphenol A

DSC Differential scanning calorimetry

DTG Differential thermogravimetry

DOE Design-of-experiment

DVB Divinyl benzene

EB Elongation at break

EMI 2-ethyl-4-methylimidazole

ESO Epoxidized soybean oil

FE-SEM Field-emission scanning electron microscopy

FTIR Fourier transforms infrared spectroscopy

GF Gel fraction

GPC Gel permeation chromatography

HBPEA Hyper branched polyester amide

HBPU Hyper branched polyurethane

HELA N, N-bis (2-hydroxyethyl) linseed oil fatty acid amide

HPLC High performance liquid chromatography

1H NMR Proton Nuclear Magnetic Resonance

xxiii

IPN Interpenetrating polymer network

LCP Liquid crystal polymer

LOFA Linseed oil fatty acid

LPU Linear polyurethane

MDI Methylene diphenyl isocyanate

MEKP Methyl ethyl ketone peroxide

MG Monoglyceride

MHHPA Methylhexa hydrophthalic anhydride

MPOB Malaysian Palm Oil Board

MTO Methyltrioxorhenium (VII)

MWCNT Multi-walled carbon nano tube

NIPU Non-isocyanate based polyurethane

NPGA N-phthaloylglutamic acid

NV Non-volatile content

PDI Polydispersity index

PEA Polyester amide

PA Phthalic anhydride

PAA Pyromellitimide acetic acid

PHBA p-hydroxybenzoic acid

PMMA Poly (methyl methacrylate)

PTSA Para-toluene sulphonic acid

PU Polyurethane

PUD Polyurethane dispersions

PVA Poly vinyl acid

rpm Revolution per minute

RSM Response surface methodology

SA Succinic anhydride

SR Swelling ratio

SEM Scanning electron microscopy

SIN Simultaneous interpenetrating network

SIPN Sequential interpenetrating polymer networks

SWCNT Single-walled carbon nano tube

TDI Toluene diisocyanate

xxiv

TGA Thermogravimetric analysis

THF Tetra hydro furan

TS Tensile strength

TTS Time−temperature superposition

VOC Volatile organic compound

XRD

X-ray diffraction

CHAPTER 1

INTRODUCTION

1.1 BACKGROUND

Polymers as versatile materials are being used in various technical purposes and

applications depending on their varieties of properties. A large range of functional

differences and behaviours has made them to be used in a wide range of applications. They

possess properties like, tough, flexible, brittle, elastomeric, plastic, fibrous, chemically-

inert, non-degradable, biodegradable, crystalline, amorphous, linear, cross-linked,

branched, hyper-branched, non-conductive, conductive, low-density, high-density, hard,

soft, rigid, light-weight, low-molecular weight, high-molecular weight, thermally-stable,

non-flammable, gas-permeable, thermoplastic, thermosetting, etc.

Generally, the monomer and its source of origin (aromatic or aliphatic, organic or

inorganic, natural or synthetic) can decide the dominating properties of polymers. For

example, aromatic originated polymers are found to be high temperature resistant due to

the presence of structurally stable benzene ring (Guner et al., 2006). On the contrary,

aliphatic polymers show relatively lower thermal stability. Except the origin or source of

the polymers, some additives or fillers like, initiator, plasticizer, stabilizer, anti-oxidant,

cross-linker (hardener), curing agent, co-monomer, compatibilizer, coupling agent, etc.

also contribute and support specific roles, which are reflected on the properties showed by

the individuals. The major portions of these polymers are made from organic sources and

mainly consist of carbon, hydrogen and oxygen atoms, although some other inorganic

atoms may be present. The endless numbers of options to create or modify the polymers

have made these materials attractive to the researchers to investigate with.

2

Innovation of new materials from renewable resources, instead of using fossil feed

stocks, is rising up day by day due to the concerns of low-cost materials, industrial

pressures for new materials and environmental sustainability. Currently, polymers are

being consumed so widely that their production has been reached 365 million tonnes in the

year 2015, and hence petroleum-based polymer industries are growing up everywhere in

the world. Petroleum resources are fixed and limited; there should be some other

alternative resources to meet the uprising demand. Nowadays, polymers from renewable

resources are attracting the researchers to work on those for advance level of researches. In

addition, high price of synthetic polymers, their non-biodegradable nature, involvedness of

significant amount of greenhouse gas emission, huge heat consumption during processing,

scarcity of the raw materials, environmental legislations or restrictions, etc. are also

important reasons for searching bio-based alternatives. The bio-based alternatives should

be inherently biodegradable and annually renewable. Among the renewable bio-based

resources, the triglyceride based vegetable oils (Luo et al., 2013; Tan et al., 2013; Das et

al., 2009a; Altuna et al., 2010; Das et al., 2010), lignin-based plant biomasses (Domínguez

et al., 2013; Xu et al., 2010) and proteins (Blomfeldt et al., 2011) are mentionable

resources from which polymers can be produced.

The current focusing area includes only vegetable oil based biopolymers and their

derivatives with major characteristics features. Vegetable oils and modified oils are being

used as main raw materials for resin preparation. For example, linseed oil and tung oil

were used for coating ingredients in oil paints and varnishes for several decades due to

their fast-drying nature (Samadzadeh et al., 2011; Xiaoyin et al., 1997). Sometimes,

modifications of non-drying oils by drying oils are found to be effective for the preparation

of bio resin. For example, modified palm oil (non-drying oil) was produced by

interesterification process with tung oil (drying oil) for the preparation of water-reducible

acrylic-alkyd resin (Saravari et al., 2005). In other applications, vegetable oil was used

with commercial resin for improved flexibility and solubility (Hintze-Bruning, 1992).

Various polymerization reactions such as, cationic (Lu et al., 2010), condensation (Sharma

et al., 2008), radical copolymerization (Saravari et al., 2005) etc. have been used to

produce various types of polymers. Among the polymers, polyesters or polyalkyds (Blaise

et al., 2012), polyester amides (Pramanik et al., 2013), epoxies (Kim et al., 2012;

Sinadinović-Fišer et al., 2012) and polyurethanes (Das et al., 2013) are mentionable.

Various types of oils such as, soybean oil (Tan et al., 2013), sunflower oil (Das et al.,

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2013), linseed oil (Pfister et al., 2010), castor oil (Sinadinović-Fišer et al., 2012), nahar

seed oil (Dutta et al., 2005), rapeseed oil and jatropha oil (Patel et al., 2008) have been

used for these purposes.

Vegetable oils are triglycerides, consisting of glycerol molecule connected with

three similar or different types of saturated or unsaturated fatty acids. Depending on the

unsaturated conditions or unsaturated fatty acids’ percentages in the oil, the route of their

modification on functional groups can be decided to produce a potential monomeric

molecule (Bailey, 1996). The produced monomer can be subjected for suitable

polymerisation process to formulate bio-polymers. The estimated amount of vegetable oils

that are being utilized to prepare different kinds of coating materials is one million tonnes

(Gunstone et al., 2007). Among the biopolymers, polyalkyds are being used efficiently in

coating industries due to their short drying time, sufficient mechanical strength and

acceptable chemical resistivity. There are several advantages of preparing polyalkyds from

vegetable oils over traditional monomer based raw materials. Especially, the cost involved

to produce plant based polyalkyds is lesser compared to the conventional polyalkyds.

Moreover, it is environmental-friendly and associated with low-energy requirement during

manufacturing. Furthermore, the polymerisation process is easy to control.

The current study deals with the reaction parameters involved in esterification

process and their optimization through response surface methodology (RSM). The

utilization of RSM was used earlier for different process optimization and found

motivational for analysing process parameters (Islam et al., 2013; Uzoh et al., 2013). The

design-of-experiment (DOE) was used for the characterization of the factors of

esterification to obtain a targeted value of response. RSM was used for polyesterification

process of palm oil in previous study (Uzoh et al., 2013). Reported results from the factor

analyses were found to be significant for the optimization process. However, in the current

study, five different types of catalysts were used prior to esterification to improve the

unsaturation in the oil through dehydration process. After that, the best catalyst was chosen

based on the highest unsaturation in the dehydrated oil and considered further for the

esterification process.

Polyalkyds have been manufactured from different types of vegetable oils such as,

palm oil, nahar seed oil, rapeseed oil, jatropha oil, etc. (Uzoh et al., 2013; Issam et al.,

4

2009; Patel et al., 2008; Dutta et al., 2004). The properties of these polymers vary due to

the constitutional composition of the fatty acids. Palm oil is non-drying oil and its

unsaturation is lower compared to other drying oils like, tung oil, soybean oil and

sunflower oil. Therefore, the drying time of palm oil based polyalkyds were found to be

longer compared to drying oils-based one. Other properties like adhesion, hardness and

chemical resistivity were also found to be moderate. Earlier, efforts were given to produce

palm oil based polyalkyds, but the documented properties were not standard due to the

presence of higher amount of saturated fatty acids in palm oil, nearly 50% (Issam et al.,

2009). Especially, the drying time was found to be longer compared to that of drying oil-

based polyalkyds. Thus due to non-drying property, palm oil was not explored extensively,

and found discouraging for polymer synthesis. To solve this problem, palm oil based

modified polyalkyds were prepared with drying oil (Ali et al., 2001). In a different study,

due to poor mechanical property, modification or blending of palm oil based polyalkyds

with commercial or petroleum based polyalkyds were studied by previous researchers

(Saravari et al., 2005).

Except the constitutional variations during manufacturing, the curing parameters

are also important to get reflected the desired properties in the formulated resins. For that,

the curing kinetics is an important measure to reveal the nature of the curing process and

other parameters involved. The widely used technique for the curing parameters

determination is differential scanning calorimetry (DSC), established since long time

before (Barton et al., 1985; Mijovic et al., 1984). Earlier, the curing process of different

materials prepared form ester functional groups were analysed by DSC (Mazali et al.,

2009; Jankovi et al., 2010; He et al., 2013; Sultania et al., 2010). In general, the dynamic

and isothermal heating methods are found to be applied for curing kinetics analysis. The

overall curing process can be depicted though single temperatures scan by analysing the

reaction parameters with the help of curing isotherms (Kay et al., 1975). Earlier, the semi-

drying oils such as, castor oil and soybean oil were used for curing kinetics analysis

(Jovicic et al., 2008). A successful transformation of the dynamic DSC data through

Ozawa kinetic model was found to be well-fitted, and the apparent degree of curing had a

significant effect on the hardness of the polymeric films produced (Ozawa, 1970).

Recent studies on the incorporation of nano materials into thermosetting polymers

are found to be effective to improve the thermo-mechanical properties of the matrix.

5

Earlier, various nano materials such as, silica, silver and carbon black were used for

different purposes. For example, they were used to enhance the corrosion resistivity, anti-

microbial activity, thermal and mechanical properties (Zhang et al., 2007a; Dolatzadeh et

al., 2011; Dinha et al., 2014). Among them, carbon nano tubes (CNTs) are potential

materials which can be used to improve the film properties of the polyalkyds. The

mechanical behaviour of CNTs and their fabrication process with suitable applications

were discussed elaborately in previous articles (Thostenson et al., 2001; Liu et al., 2004;

Choi et al., 2004). The processing of nanotubes or nanoparticles incorporation into liquid

resin or polymers was found to be a tedious job for a uniform and evenly dispersion, which

was considering a major shortcoming of this material (Gibson et al., 2007). The

agglomeration or cluster formation of nanotubes is the reason for uneven or poor

dispersion of them into the polymer matrix. Thus the aim of this research work is to

disperse CNTs by physical stirring with the help of magnetic rotor in the presence of

minimum frequency of ultrasound and following in-situ reaction technique during

esterification process.

1.2 PROBLEM STATEMENT

Commercially available polymers are derived from non-renewable resources,

mostly from fossil fuels, whose reservations are reducing day by day due to high demand.

These polymers are not environmental-friendly, associated with higher manufacturing cost,

non-biodegradable, and hence encounter disposable problems. During their manufacturing

process, huge amount of heat energy along with greenhouse gas emissions are involved,

which are harmful for the world’s sustainability. All this issues derive the researchers to

find new, renewable, environmental-friendly and bio-based resources for polymer

synthesis.

Recently, polyalkyds from drying oils have drawn interests among the researchers

for their excellent drying property, which is absent in non-drying based polyalkyds. Palm

oil is non-drying oil and the reported drying properties are not up to the level of drying oil

based products, but the production of palm oil is highest compared to other vegetable oils

worldwide. This huge amount can be used for the polymer production for the economic

benefit and sustainability. Moreover, the price of this oil is very less compared to others.

Therefore, improvement of drying property is essential for palm oil based polyalkyds.

Table of content ACH 1 to CH 5 B

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