i characterization of irradiated epoxidized...

i

CHARACTERIZATION OF IRRADIATED EPOXIDIZED NATURAL

RUBBER/POLYVINYL CHLORIDE/CARBON NANOTUBES

NANOCOMPOSITES

MOHD SHAHRULNIZAM BIN AHMAD

A thesis submitted in fulfilment of the

requirements for the award of the degree of

Master of Engineering (Polymer)

Faculty of Chemical and Energy Engineering

Universiti Teknologi Malaysia

JANUARY 2017

iii

I dedicate this dissertation to my family…

Dad and Mom,

Ahmad Bin Kadir for opening my eyes to the World;

Khalijah Binti Siolin for instilling the importance of hard work and higher education

Sisters and Brothers,

Siti Rohaidah, Siti Zarina, Norazzah, Norisham,

Shahbuddin, Amiruddin and Reduwan

for their supports and encouragement;

Last but not least, to all my nephews and nieces;

I also dedicate this dissertation to all my beloved friends for being a best friend and

great source of motivation and inspiration

Finally, I dedicate this dissertation to all my ex-classmates

(SKR Batch 2009/2013)…

iv

ACKNOWLEDGEMENT

Foremost, I would like to express my deep and sincere gratitude to my

supervisor, Prof. Madya Dr Zurina Mohamad for the continuous support of my final

year project, for her patience, motivation, enthusiasm and immense knowledge. Her

understanding, encouraging and personal guidance have provided a good basis for

presenting this thesis. Thank for patiently correcting my writing and financially

supported my research. Not forgetting Dr Chantara Thevy Ratnam who has helped

me a lot in guidance me at Malaysian Nuclear Agency.

This thesis would be incomplete without special thanks to En Wan and Kak

Juju who are from Malaysian Nuclear Agency for their kind advice and support

during the research is conducted. I wish to express my warmest thanks also to all

Department Polymer Engineering members for all their support and friendship over

the year. In particular, Cik Haslinda, En Hasnol, En Hafiz and En Falah. Thanks to

all mates at Malaysian Nuclear Agency for helping me a lot to finish this project.

I owe my loving thanks to my parents and my siblings for their patient and

loving advice to me. Without their encouragement and understanding it has been

impossible for me to finish this postgraduate project. They were always supporting

me with their best wishes.

v

ABSTRACT

The effects of carbon nanotubes addition and irradiation modification on the

characterization and properties of epoxidized natural rubber (ENR-50)/poly(vinyl

chloride) (PVC)/multi-walled carbon nanotubes (MWNTs) nanocomposites were

investigated. ENR-50/PVC/MWNTs nanocomposites were prepared by melt mixing

in a Brabender Plastigraph at 150 °C with a rotor speed of 50 rpm followed by

compression molding at 160 °C. The samples were irradiated in a 2 MeV electron

beam machine in a dose range from 50 to 200 kGy. The functional groups, gel

content, morphology, dynamic mechanical properties, volume resistivity and tensile

properties of the resulting composites were investigated as a function of MWNTs

contents, functionalized MWNTs and irradiation dose. Gel content confirmed the

existence of irradiation-induced crosslinking. The highest gel content value was

recorded at 8 phr of MWNTs content in nanocomposites. At 0 kGy (up to 6 phr), the

MWNTs-COOH had higher gel content value. However, after irradiation (150 kGy),

MWNTs nanocomposites recorded the highest gel content value. The x-ray

diffraction pattern showed that 2 phr MWNTs content nanocomposites had a better

degree of crystallinity than 8 phr MWNTs content and the degree of crystallinity

was enhanced after irradiation. The addition of 8 phr of all MWNTs led to the

increase of storage modulus and glass transition temperature, and was further

enhanced after irradiation (200 kGy). Based on dynamic mechanical analysis results,

8 phr of functionalized MWNTs had better crosslinking as compared with

unfunctionalized MWNTs. Volume resistivity increased with increasing MWNTs

contents and irradiation dosage. The functionalized MWNTs showed higher

resistivity at 0 and 150 kGy of irradiation doses. The tensile strengths of the

irradiated nanocomposites increased up to 8 phr of unfunctionalized MWNTs, 6 phr

of MWNTs-COOH and 10 phr of MWNTs-OH above 50 kGy. The modulus 100

(M100) increased and elongation at break (Eb) decreased with increasing of

MWNTs content and irradiation doses. Functionalized MWNTs showed higher

M100 and lower Eb at 0 kGy. However at 200 kGy of irradiation dose, the M100

was lowered and Eb was higher for functionalized MWNTs nanocomposites.

vi

ABSTRAK

Kesan penambahan tiub nano karbon dan pengubahsuaian penyinaran ke atas

ciri-ciri dan sifat getah asli terepoksida (ENR-50)/poli(vinil klorida) (PVC)/tiub nano

karbon pelbagai dinding (MWNTs) komposit nano telah dikaji. ENR-

50/PVC/MWNTs komposit nano telah disediakan melalui campuran leburan

menggunakan Brabender Plastigraph pada suhu 150 °C dengan kelajuan rotor 50 rpm

diikuti dengan pengacuan mampatan pada suhu 160 °C. Seterusnya, sampel

disinarkan di dalam mesin alur elektron 2 MeV dalam julat dos di antara 50-200

kGy. Kumpulan berfungsi, kandungan gel, morfologi, sifat mekanikal dinamik,

isipadu kerintangan dan sifat regangan bagi komposit yang terhasil telah dikaji

sebagai fungsi kepada kandungan MWNTs, MWNTs berfungsi dan dos penyinaran.

Kandungan gel telah mengesahkan kehadiran sambung silang teraruh-penyinaran.

Nilai kandungan gel pada 8 phr kandungan MWNTs adalah tertinggi. Pada 0 kGy

(sehingga 6 phr), MWNTs-COOH mempunyai nilai kandungan gel yang paling

tinggi. Walau bagaimanapun, selepas penyinaran (150 kGy), komposit nano

MWNTs merekodkan nilai kandungan gel yang paling tinggi. Analisis pembelauan

sinar-x menunjukkan komposit nano dengan kandungan MWNTs 2 phr mempunyai

tahap penghabluran yang lebih baik berbanding 8 phr kandungan MWNTs dan

struktur penghabluran dipertingkatkan selepas penyinaran. Penambahan 8 phr pada

kesemua MWNTs membawa kepada peningkatan modulus simpanan dan suhu

peralihan kaca dan dipertingkatkan lagi selepas penyinaran (200 kGy). Berdasarkan

keputusan analisa mekanikal dinamil, untuk 8 phr MWNTs berfungsi, komposit

nano mempunyai sambung silang yang lebih baik daripada MWNTs tanpa fungsi.

Isipadu kerintangan meningkat dengan penambahan MWNTs dan dos penyinaran.

Selain itu, MWNTs berfungsi mempunyai isipadu kerintangan yang tinggi pada dos

penyinaran 0 dan 150 kGy. Sifat regangan komposit nano yang disinarkan telah

meningkat pada 8 phr MWNTs, 6 phr MWNTs-COOH dan 10 phr MWNTs-OH

selepas 50 kGy penyinaran. Modulus 100 (M100) meningkat dan pemanjangan pada

takat putus (Eb) menurun dengan kenaikan kandungan MWNTs dan dos penyinaran.

MWNTs berfungsi merekodkan M100 yang tinggi dan Eb yang rendah pada 0 kGy.

Walau bagaimanapun, pada dos penyinaran 200 kGy, M100 menjadi rendah dan Eb

menjadi tinggi untuk komposit nano MWNTs yang berfungsi.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF ABBREVIATIONS xviii

LIST OF SYMBOLS xx

1 INTRODUCTION 1

1.1 Background of the Study 1

1.2 Problem Statement 4

1.3 Objectives of the Study 5

1.4 Scope of the Study 5

viii

2 LITERATURE REVIEW 7

2.1 Polymer Blends 7

2.1.1 Overview and Definition 7

2.1.2 Technique of Polymer/Fillers Nanocomposites 9

2.2 Thermoplastic Elastomer Blends 10

2.3 Epoxidized Natural Rubber 13

2.3.1 Preparation and Structure 13

2.4 Polyvinyl Chloride 14

2.5 Nanocomposites 16

2.5.1 Introduction 16

2.5.2 Nanocomposites Structure 17

2.6 Thermoplastic Elastomers Nanocomposites 19

2.7 Carbon Nanotubes (CNTs) 21

2.7.1 Introduction 21

2.7.2 Properties of CNTs 22

2.7.3 Functionalization of CNTs 24

2.7.4 Multi-Walled Carbon Nanotubes (MWNTs) 26

2.7.5 CNTs Nanocomposites 27

2.8 Electron Beam Processing of Polymers 28

2.8.1 Introduction of Electron Beam Irradiation 28

2.9 Polymer Crosslinking 33

3 METHODOLOGY 36

3.1 Materials and Equipment 36

3.2 Sample Preparation 37

3.2.1 Blend Preparation 37

3.2.2 Molding 38

3.2.3 Irradiation 38

3.3 Fourier Transform Infrared Spectroscopy (FTIR) 39

3.4 Gel Content 39

3.5 Morphological Test 40

3.5.1 Scanning Electron Microscopy 40

3.5.2 Transmission Electron Microscope 40

ix

3.5.3 Characterization on XRD Pattern 40

3.6 Dynamic Mechanical Analysis 41

3.7 Volume Resistivity 41

3.8 Measurement of Tensile Properties 41

4 RESULTS AND DISCUSSION 42

4.1 Fourier Transform Infrared Spectroscopy Analysis 42

4.2 Gel Content 52

4.3 Characterization on XRD Pattern 59

4.4 Dynamic Mechanical Analysis 64

4.5 Volume Resistivity 73

4.6 Torque 80

4.7 Measurement of Tensile Properties 84

5 CONCLUSION AND RECOMMENDATION 111

5.1 Conclusion 111

5.2 Recommendation 114

REFERENCES 115

x

LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Dimension and corresponding number of particles

in composites for different fillers. 18

2.2 Physical properties of different carbon materials. 23

2.3 Frequency and wavelength of various irradiations. 30

2.4 Categorization of polymers according to the

preponderate behavior on irradiation. 32

3.1 Formulation of ENR-50/PVC/MWNTs

nanocomposites. 37

4.1 DMA data for unirradiated ENR-50/PVC/MWNTs

nanocomposites at 0 kGy of irradiation dose. 65

4.2 DMA data for irradiated ENR-50/PVC/MNWTs

nanocomposites at 200 kGy of irradiation dose. 65

xi

LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Schematic of the polymer blending process. 8

2.2 Schematic representation of different steps

polymer/MWNTs composites preparation:

(a) solution mixing; (b) melt mixing;

(c) in-situ polymerization . 10

2.3 Mechanism of NR epoxidation with a peracid. 14

2.4 Structure of polyvinyl chloride. 15

2.5 Distribution of micro- and nano-scale fillers.

of the same 0.1 vol.% in a reference volume

of 1 mm3 (A: Al2O3 particle; B: carbon fiber;

C: GNP; D: CNT). 18

2.6 TEM micrograph of 30% content of NBR

and 7% content of Cloisite (PN30C7)

nanocomposites. 20

2.7 Schematic diagram showing how a hexagonal

sheet of graphene is rolled to form a CNTs with

distinct chiralities (A: armchair; B: zigzag

C: chiral). 22

2.8 X-ray diffraction patterns for

(a) SWNT and (b) MWNTs 24

2.9 Procedures for covalent functionalization of

CNTs (A: direct wall functionalization;

B: defect functionalization). 26

2.10 Structure of a multi-walled carbon nanotubes

made up of three shells of different chirality. 27

2.11 Schematic diagram of common Electron Beam

Accelerator and identical circuit diagram of

electron gun. 30

xii

2.12 Plausible mechanism of crosslinking between

ENR-50 and PVC. 34

2.13 Branched and crosslinked polymer molecules.

While a branched polymer molecule retains finite

size and an identifiable molecular weight, the

crosslinked polymer forms a three-dimensional

network of macroscopic proportions. (A rubber

band is essentially one molecule, since any two

atoms are connected ultimately by covalent

bonds.) 35

4.1 FTIR spectrums on ENR-50/PVC/MWNTs and

its functionalization at 2 phr of nanotube

content (0 kGy). 45



content (0 kGy). 46



content (200 kGy). 47



content (200 kGy). 48

4.5 Formation of aldehyde –C=O groups indicated

by the peak at 1730cm-1

. 49

4.6 Formation of ether linkage indicated by the

peak at 1238cm-1

. 49

4.7 The formation of furanized rings indicated

by the peak at 1060cm-1

. 50

4.8 The formation of ether crosslinks between

ENR-50/PVC. 51

4.9 Mechanism of free radical formed. 52

4.10 Effect of irradiation dose on gel content of

ENR-50/PVC blends with different

functionalization of MWNTs:

(a) MWNTs; (b) MWNTs-COOH and

(c) MWNTs-OH nanocomposites at

different nanotube contents. 55

4.11 Effect of irradiation dose and nanotube

content on gel content of

ENR-50/PVC/MWNTs nanocomposites. 56



ENR-50/PVC/MWNTs-COOH nanocomposites. 56

xiii



ENR-50/PVC/MWNTs-OH nanocomposites. 57

4.14 Effect of nanotube content on gel content

of ENR-50/PVC/MWNTs nanocomposites

and its functionalization at 0 kGy of

irradiation dose. 58

4.15 Effect of nanotube content on gel content




4.16 XRD pattern on ENR-50/PVC/MNWTs

nanocomposites at different MWNTs

loading (0 kGy). 61


nanocomposites at different MWNTs

loading (200 kGy). 62


nanocomposites and its functionalization

at 8 phr loading (0 kGy). 63


nanocomposites and its functionalization

at 8 phr loading (200 kGy). 64

4.20 Effect of nanotube content of MWNTs on the

temperature dependence of tan δ and storage

modulus of 50/50 ENR-50/PVC blend with

0 kGy irradiation dose. 67


temperature dependence of loss modulus

of 50/50 ENR-50/PVC blend with 0 kGy



temperature dependence of tan δ and storage

modulus of 50/50 ENR-50/PVC blend with

200 kGy irradiation dose. 68


temperature dependence of loss modulus

of 50/50 ENR-50/PVC blend with 200 kGy


4.24 Effect of functionalization of MWNTs

(8 phr) on the temperature dependence of tan δ

and storage modulus of 50/50 ENR-50/PVC

blend with 0 kGy irradiation dose. 71

xiv


(8phr) on the temperature dependence of

loss modulus of 50/50 ENR-50/PVC blend

with 0 kGy irradiation dose. 71


(8 phr) on the temperature dependence of tan δ

and storage modulus of 50/50 ENR-50/PVC

blend with 200 kGy irradiation dose. 72


(8 phr) on the temperature dependence of

loss modulus of 50/50 ENR-50/PVC blend

with 200 kGy irradiation dose. 73

4.28 Effect of irradiation dose on volume resistivity

of ENR-50/PVC blends with different

functionalization of MWNTs: (a) MWNTs;

(b) MWNTs-COOH and (c) MWNTs-OH

nanocomposites at different nanotube

content. 76

4.29 Effect of irradiation dose and nanotube content

on volume resistivity of








4.32 Effect of nanotube content on volume resistivity

of ENR-50/PVC/MWNTs nanocomposites and

its functionalization at 0 kGy irradiation dose. 79

4.33 Effect of nanotube content on volume resistivity

of ENR-50/PVC/MWNTs nanocomposites and

its functionalization at 150 kGy irradiation dose. 80

4.34 Torque value of Brabender Plastigraph

for ENR-50/PVC/MWNTs nanocomposites at

different MWNTs loading. 82

4.35 Torque value of Brabender Plastigraph for

ENR-50/PVC/MWNTs-COOH nanocomposites

at different MWNTs-COOH loading. 82

4.36 Torque value of Brabender Plastigraph for

ENR-50/PVC/MWNTs-OH nanocomposites

at different MWNTs-OH loading. 83

xv

4.37 Effect of irradiation dose on tensile strength of

ENR-50/PVC blends with different

functionalization of MWNTs: (a) MWNTs;

(b) MWNTs-COOH and (c) MWNTs-OH

nanocomposites at different nanotube

contents. 87


on tensile strength of








4.41 Low-magnification (10,000 x) of

TEM micrograph:

(a) ENR-50/PVC/2 phr of MWNTs (0 kGy),

(b) ENR-50/PVC/2 phr of MWNTs (200 kGy),

(c) ENR-50/PVC/8 phr of MWNTs (0 kGy) and

(d) ENR/PVC/8 phr of MWNTs (200 kGy). 90

4.42 Low-magnification (100 x) of SEM micrograph:

(a) ENR-50/PVC (0 kGy),

(b) ENR-50/PVC (200 kGy),

(c) ENR-50/PVC/2 phr of MWNTs (0 kGy),

(d) ENR-50/PVC/2 phr of MWNTs (200 kGy),

(e) ENR-50/PVC/8 phr of MWNTs (0 kGy) and

(f) ENR-50/PVC/8 phr of MWNTs (200 kGy). 91

4.43 High-magnification (1000 x) of SEM

micrograph: (a) ENR-50/PVC (0 kGy),

(b) ENR-50/PVC (200 kGy),

(c) ENR-50/PVC/2 phr of MWNTs (0 kGy),

(d) ENR-50/PVC/2 phr of MWNTs (200 kGy),

(e) ENR-50/PVC/8 phr of MWNTs (0 kGy) and

(f) ENR-50/PVC/8 phr of MWNTs (200 kGy). 92

4.44 Low-magnification (10,000 x) of TEM

micrograph:


(b) ENR-50/PVC/2 phr MWNTs (200 kGy),

(c) ENR-50/PVC/2 phr of MWNTs-COOH

(0 kGy),

(d) ENR-50/PVC/2 phr of MWNTs-COOH

(200 kGy),

(e) ENR-50/PVC/2 phr of MWNTs-OH

(0 kGy) and

(f) ENR-50/PVC/2 phr of MWNTs-OH

(200 kGy). 93

xvi

4.45 Effect of nanotube content on tensile strength












4.48 Low-magnification (100 x) of

SEM micrograph:




(0 kGy),


(200 kGy),


(0 kGy) and


(200 kGy). 97

4.49 High-magnification (1000 x) of

SEM micrograph:




(0 kGy),


(200 kGy),


(0 kGy) and


(200 kGy). 98

4.50 Effect of irradiation dose on modulus at

100% elongation of ENR-50/PVC blends

with different functionalization of MWNTs:

(a) MWNTs; (b) MWNTs-COOH and

(c) MWNTs-OH nanocomposites at

different nanotube content. 100


on M100 of ENR-50/PVC/MWNTs

nanocomposites. 101

xvii


on M100 of ENR-50/PVC/MWNTs-COOH

nanocomposites. 101


on M100 of ENR-50/PVC/MWNTs-OH

nanocomposites. 102

4.54 Effect of nanotube content on M100 of

ENR-50/PVC/MWNTs nanocomposites



4.55 Effect of nanotube content on M100 of




4.56 Effect of nanotube content on M100




4.57 Effect of irradiation dose on Eb of ENR-50/PVC

blends with different functionalization of

MWNTs: (a) MWNTs; (b) MWNTs-COOH

and (c) MWNTs-OH nanocomposites at

different nanotube content. 106


on Eb of ENR-50/PVC/MWNTs.

nanocomposites. 107


on Eb of ENR-50/PVC/MWNTs-COOH

nanocomposites. 107


on Eb of ENR-50/PVC/MWNTs-OH

nanocomposites. 108

4.61 Effect of nanotube content on Eb of












xviii

LIST OF ABBREVIATIONS

ASTM - American Standard Test Method

BS - British Standard

CNT - Carbon nanotubes

DMA - Dynamic mechanical analysis

DMTA - Dynamic mechanical thermal analysis

DSC - Differential scanning calorimetry

DTG - Derivative thermograms

DWNTs - Double – walled carbon nanotubes

Eb - Elongation at break

EB - Electron – beam

ECO - Polyepicchlorohydrin-co-ethylene

EDX - Electron dispersion X – ray analyzer

ENR - Epoxidized natural rubber

EVA - Ethylene vinyl acetate

FTIR - Fourier transform infrared spectroscopy

GNP - Graphite Nanoplatelets

LDPE - Low density polyethylene

LLDPE - Liner low density polyethylene

LNR - Liquid natural rubber

M100 - Modulus at 100% elongation

MAH - Maleic anhydride

MMR - Montmorillonite

MPa - Megapascal

MWNTs - Multi – walled carbon nanotubes

MMR - Montmorillonite

xix

MWNTs - Multi – walled carbon nanotubes

NBR - Acrylnonitrile butadiene – rubber

PA6 - Polyamide 6

PE - Polyethylene

PEI - Polyetherimide

PI - Polyimide

PP - Polypropylene

PU - Polyurethane

PVC - Polyvinyl chloride

PVCw - Waste poly(vinylchloride)

SEM - Scanning electron microscopy

SMR - Standard Malaysia Rubber

SWNTs - Single-walled carbon nanotubes

TEM - Transmission electron microscopy

TGA - Thermo gravimetric analysis

TPE - Thermoplastic elastomer

UV - Ultraviolet

XRD - X-ray diffraction

xx

LIST OF SYMBOLS

°C - Temperature in degree Celsius

GPa - Gigapascal

Hz - Hertz

kN - Kilonewton

kGy - KiloGray (radiation unit of measure)

mA - Milliampere

MeV - Megaelectron volt

MPa - Megapascal

nm - Nanometer

rpm - Revolution per minute

TPa - Terapascal

Tg - Glass transition temperature

CHAPTER 1

INTRODUCTION

1.1 Background of the Study

Polymer blending is a common technology, frequently applied in order to

produce a product with superior mechanical properties of inexpensive polymer

material and small amounts of compatibilizers. The large diversity of commercially

available elastomers and thermoplastics offers huge opportunities for blending of

thermoplastic elastomers (TPEs).

The basis of epoxidized natural rubber (ENR) is from the chemical alteration

of natural rubber (NR). In obtaining ENR, carbon-carbon double bond on the NR

molecular chains being converted into the polar epoxy group, when the free volumes

of chain phases is decreased and the density and polarity of the derivates are

increased, which can provide the ENR with excellent impermeability of air, oil and

organics solvent proofness and performance of wet road grip (Yu et al., 2008).

2

Characteristics of polyvinyl chloride (PVC) can improve ozone and resistance

of mechanical in some applications such as conveyor, fuel hose, belt covers and

printing roll covers (Ismail and Supri., 2004). Ratnam et al. (2001) reported that

ENR forms miscible blends with PVC in which PVC is expected to impart high

tensile strength and good chemical resistance whereas ENR acts as a permanent

plasticizer to PVC, induces good tear strength and enhances the resistance against

hydrocarbon oils.

Studies on the blends between ENR-50/PVC had been reported (Ratnam,

2002). Various researchers have reported on the attainment of miscible, well – fused

and homogenous ENR-50/PVC blends in relation to the improvement in mechanical

and physical properties of the blend. Properties of ENR-50/PVC blends can be

improved by electron beam irradiation. The studies revealed by Ratnam et al. (2006)

that they can be crosslinked by irradiation.

ENR-50/PVC blends were found to be miscible over the entire composition

ranges. ENR-50/PVC blends have many potential areas of usage such as cable

jackets, conveyer belt covers, hose linings and covers, cellular sporting surfaces and

footwear. High energy irradiation (gamma and electron beam) is a well-known

technique for polymer modification (Ratnam and Zaman, 1999). Electron beam

processing needs high energy electrons from an accelerator for crosslink reactions

and initiate polymerization in suitable matrices, thus improving their specific

physical and also chemical properties.

Nanocomposites exhibit important enhancement in mechanical and physical

properties in relation to the polymer host. The stiffness and strength with a minimal

loss in ductility and impact resistance can be enhanced by adding of the minimum

percentage of nanofiller. Other than that, it also can help in increasing of

permeability and swelling in solvents, abrasion improvement, flame resistance and

thermal endurance, with an improvement optical properties and electrical

conductivity (Arroyo et al., 2007).

3

There are many uses of carbon nanotubes in engineering application and

electronics such as photovoltaic devices, nanoelectronic, superconductors,

electrochemical actuators, nanowires and electrochemical capacitors. This nanotube

can be divided into several types such as single-walled carbon nanotubes (SWNTs),

double-walled carbon nanotubes (DWNTs) and multi-walled carbon nanotubes

(MWNTs). Sahoo et al. (2010) reported that the presence of carbon nanotubes can

enhance the properties of polymer composites including tensile strength, tensile

modulus, toughness, glass transition temperature, electrical conductivity, thermal

conductivity, optical properties, solvent resistance, etc.

SWNTs and DWNTs compose cylinders of one or two (concentric),

respectively, graphene sheets, whereas MWNTs consists several concentric

cylindrical shells of graphene sheets (Sahoo et al., 2010). Sahoo et al. (2010) also

reported that production of CNTs has variety of methods such as laser ablation, arc

discharge, high pressure carbon monoxide (HiPCO) and chemical vapor deposition

(CVD).

Irradiation can be utilized to strengthen the characteristics of polymer blends

and composites. Irradiation also can help to induce crosslinking like those obtained

by sulphur curing, but the net effects, while similar, are not identical. The type of

carbon-carbon crosslink formed in this method enhances the mechanical properties at

higher temperature. Also, it can lead to greater resistance of abrasion and superior

ozone resistance (Khalid et al., 2010).

In this study the irradiation effect on the properties of ENR-50/PVC blends

filled with functionalized and unfuntionalized MWNTs will be investigated.

4

1.2 Problem Statement

The use of ENR/PVC blends is commonly used in conveyer belt covers, hose

linings and covers, cable jackets, cellular sporting surfaces and footwear (Ratnam

and Zaman, 1999). From these applications, this blend is also expected very suitable

to use in interior part of car such as gasket and o-ring which are exposed to the

higher temperature and dynamic movement. Otherwise, work on ENR/PVC blend

might be has some weaknesses such as low in mechanical strength, electrical

conductivity and also thermal properties as compared with addition of nanofiller and

irradiation modification. Moreover, the ENR/PVC blend had found its commercial

applications, work on the improvement of its properties still become the subject of

interest. Broza et al. (2007) reported that in the presence of MWNTs the electrical

conductivity had increased with increasing of MWNTs in the PVC matrix. This was

due to MWNTs are homogenously distributed in the PVC matrix. Study on

polyurethane (PU)/CNTs nanocomposites that had done by Sahoo et al. (2006)

reported that adding of CNTs into PU had drastically increased the tensile strength

and also modulus. So et al. (2007) also reported that in-situ polymerized PI

containing MWNTs-COOH showed increment in tensile strength and modulus as

compared to that of the neat PI. Hence, the modification of this blend is needed in

order to enhance its overall properties. The main aim of this research is to enhance

the current properties of ENR/PVC blends with incorporation of multi-walled carbon

nanotubes (MWNTs) and functionalized MWNTs. This is due to the superior

properties of MWNTs are not limited to electrical and thermal conductivities, and

also included mechanical properties (Sahoo et al., 2010). Furthermore, enhancement

is expected when the use of MWNTs is along with irradiation. This is because

ionising irradiation can induce crosslinks of the blends.

5

1.3 Objective of the Study

In this research, the main objective is to characterize ENR-50/PVC/MWNTs

nanocomposites. This can be further divided into:

(i) To investigate the effect of MWNTs loading on the properties of the ENR-

50/PVC/MWNTs nanocomposites.

(ii) To investigate the effect of functionalized MWNTs (MWNTs-COOH and

MWNTs-OH) on the properties of the ENR-50/PVC/MWNTs

nanocomposites.

(iii)To investigate the effect of irradiation dose on the properties of the

functionalized and unfunctionalized ENR-50/PVC/MWNTs nanocomposites.

1.4 Scope of the Study

In this research, the materials required are epoxidized natural rubber, ENR-50

(rubber), polyvinyl chloride, PVC (thermoplastic), multi-walled carbon nanotubes,

MWNTs (nanofiller). Equipments used are Brabender Plastigraph W 50 E-3 Zones,

Hot and Cold Press Machine Scientific Laboratory Hydraulic Press Type LP-S-50

and 2 MeV electron beam accelerator Model EPS 3000 (Cockroft Walton).

Moreover, compounding of ENR-50/PVC/CNT by using Brabender Plastigraph and

the compound subjected to Hot Press Machine in order to produce samples 1-, 2-,

and 2.5- mm thick sheet form. In this research, there are a few aspects of testing

involved such as physical, mechanical, thermal, electrical and also morphological

tests. Firstly, Fourier transform infrared spectroscopy (FTIR) is to determine the

interaction between the components in nanocomposites. In aspect of physical

properties, gel content is to measure the crosslinking percentage of nanocomposites.

Other than that, there are a few of morphological which are scanning electron

6

microscopy (SEM), to observe the morphology behavior of polymer phase in

nanocomposites, transmission electron microscope (TEM), to observe the dispersion

of MWNTs filler and its functionalized in polymer matrix and characterization on

XRD-pattern, to investigate the interaction between MWNTs filler and ENR-50/PVC

matrix and to access the effect of MWNTs content on the crystallinity of polymer

matrix. Dynamic mechanical analysis (DMA), the parameters that measured is glass

transition temperature (Tg), storage modulus and loss modulus.in order to investigate

thermal properties of nanocomposites. For electrical properties, volume resistivity is

to quantify how strongly a given material opposes the flow of electric current.

Lastly, the measurement of tensile properties included in calculation of tensile

strength (Ts), modulus 100 (M100) and elongation at break (Eb).

http://en.wikipedia.org/wiki/Electric_current

115

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