UNIVERSITI PUTRA MALAYSIA

SHAZED MD. AZIZ

FK 2013 8

EXPERIMENTAL AND THEORETICAL EVALUATION OF THE TENSILE PROPERTIES OF CARBON NANOTUBE-COATED CARBON

FIBRE HYBRID COMPOSITES

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EXPERIMENTAL AND THEORETICAL

EVALUATION OF THE TENSILE PROPERTIES

OF CARBON NANOTUBE-COATED CARBON

FIBRE HYBRID COMPOSITES

SHAZED MD. AZIZ

MASTER OF SCIENCE

UNIVERSITI PUTRA MALAYSIA

2013

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DEDICATION

To my belated parents,

with memories…

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Abstract of thesis presented to the Senate of Universiti Putra Malaysia in fulfilment

of the requirement for the degree of Master of Science

EXPERIMENTAL AND THEORETICAL EVALUATION OF THE TENSILE

PROPERTIES OF CARBON NANOTUBE-COATED CARBON FIBRE

HYBRID COMPOSITES

By

SHAZED MD. AZIZ

February 2013

Chair : Associate Professor Suraya binti Abdul Rashid, PhD

Faculty : Engineering

Hierarchically structured hybrid composites are ideal engineered materials to carry

loads and stresses due to their unconventional in-plane specific mechanical

properties such as tensile modulus, strength, and stiffness. Growing carbon

nanotubes (CNT) on the surface of high performance carbon fibres (CF) provides a

means to tailor the mechanical properties of the fibre-matrix interface of a composite.

The growth of CNT onto the surface of CF was conducted via floating catalyst

chemical vapor deposition (CVD) technique. The mechanical properties of the

resultant fibres, CNT density and alignment morphology were shown to depend on

the CNT growth temperature, growth time, carrier gas flow rate, catalyst amount, and

atmospheric conditions within the CVD chamber. The evidence of intensive CNT-

coating on CF was shown at a CVD temperature of 700 °C and 30 minutes reaction

time by using Scanning electron microscope (SEM). Single fibre/Epoxy composite

coupons were fabricated by using both neat and CNT-coated CF to conduct single

fibre fragmentation test (SFFT). For neat-CF/Epoxy composite coupons, IFSS was

found to be 12.52 MPa. A CNT-coated CF demonstrated approximately 45%

increase in calculated IFSS when treated at 700 °C and 30 minutes reaction

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environment over that of the untreated fibre from which it was processed. Carbon

nanotube coated short carbon fibre reinforced polypropylene (CNT-CF/PP)

composites were fabricated. The resulting hybrid composite samples were

characterized using the tensile testing method. For neat-CF/PP composite, Young’s

modulus and tensile strength were found to be 1.72 GPa and 20.5 MPa respectively.

In contrast with the neat CF/PP composite, CNT-CF/PP composite has shown

enhanced Young’s modulus by approximately 104% and tensile strength increased to

approximately 64%. The fibre-matrix adhesion was analyzed by using SEM on

cryogenically fractured surface of both types of composites. The proper justification

of fibre-matrix interfacial adhesion featuring the composite tensile properties was

explained through interfacial shear strength (IFSS). Composites with high IFSS was

found to show a high Young’s modulus and tensile strength. Theoretical prediction

of hybrid CNT-CF/PP composite tensile properties was accomplished by using a

hierarchical model which comprises Halpin–Tsai equations, Combined Voigt-Reuss

model, simple rule-of-mixtures (RoM) and Krenchel approach. When the internal

geometry of composite was a key factor RoM was utilized to study the fibre

orientation distribution in the composite. A comprehensive fractographic

investigation was carried out with scanning electron microscope (SEM) to analyze

the fibre orientation distribution on the CNT-CF/PP composite fracture surfaces.

Then, a thorough analysis was done on the SEM images using Bersoft and Geozebra

image analyzing software packages to evaluate the fibre orientation distribution

factor ( 0η ). In the context of this approach, when the fibre orientation effect is

ignored a noteworthy deviation in tensile modulus with 51% was notified rather than

experimental result of 1.72 GPa. When 0η is considered a more acceptable validation

with the experimental results of tensile modulus was obtained which shows a

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moderate deviation with 30% to the predicted value of 4.57 GPa. Finally, the

discrepancies between the predicted and experimental values were explained in terms

of stress-strain behavior.

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Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai

memenuhi keperluan untuk Ijazah Sarjana Sains

PENILAIAN UJIKAJI DAN TEORI MENGENAI SIFAT TEGANGAN

KARBON NANOTUBE BERSALUT-GENTIAN KARBON HIBRID RENCAM

Oleh

SHAZED MD. AZIZ

Februari 2013

Pengerusi : Profesor Madya Suraya Binti Abdul Rashid, PhD

Fakulti : Kejuruteraan

Struktur hierarki komposit hibrid adalah ideal kejuruteraan bahan-bahan untuk

membawa beban dan menekankan kerana tidak konvensional mereka dalam-satah

sifat-sifat tertentu mekanikal seperti modulus tegangan, kekuatan, dan kekakuan.

Berkembang nanotube karbon (CNT) pada permukaan gentian karbon berprestasi

tinggi (CF) menyediakan satu cara untuk menyesuaikan sifat mekanikal antara muka

gentian-matriks komposit. Pertumbuhan CNT ke permukaan CF telah dijalankan

melalui terapung pemangkin teknik pemendapan wap kimia (CVD). Sifat-sifat

mekanikal gentian yang terhasil, ketumpatan CNT dan morfologi penjajaran

ditunjukkan bergantung kepada suhu pertumbuhan CNT, masa pertumbuhan, kadar

aliran gas pembawa, jumlah mangkin, dan keadaan atmosfera dalam kebuk CVD.

Keterangan intensif CNT-salutan pada CF telah ditunjukkan pada suhu CVD 700 ° C

dan 30 minit masa tindak balas dengan menggunakan Mengimbas mikroskop

elektron (SEM). Single fiber/Epoxy kupon komposit telah direka dengan

menggunakan kedua-dua CF kemas dan bersalut CNT untuk menjalankan serat ujian

pemecahan tunggal (SFFT). Untuk neat-CF/Epoxy kupon komposit, IFSS didapati

menjadi 12,52 MPa. A CF CNT bersalut menunjukkan peningkatan kira-kira 45%

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dalam IFSS dikira apabila dirawat pada 700 °C dan 30 minit tindak balas

persekitaran yang lebih serat yang tidak dirawat dari mana ia telah diproses. Karbon

nanotube bersalut karbon pendek bertetulang gentian polipropilena (CNT-CF/PP)

komposit telah direka. Yang terhasil sampel komposit hibrid telah dicirikan

menggunakan kaedah ujian tegangan. Untuk neat-CF/PP komposit, Young’s

modulus dan kekuatan tegangan telah didapati menjadi 1.72 GPa dan 20.5 MPa

masing-masing. Berbeza dengan komposit neat-CF/PP, CNT-CF/PP komposit telah

ditunjukkan meningkatkan modulus Young oleh kira-kira 104% dan kekuatan

tegangan meningkat kepada kira-kira 64%. Rekatan gentian-matriks telah dianalisis

dengan menggunakan SEM pada permukaan cryogenically patah kedua-dua jenis

komposit. Justifikasi yang betul melekat gentian-matriks memaparkan sifat tegangan

komposit telah dijelaskan melalui kekuatan ricih antara muka (IFSS). Composites

with high IFSS was found to show a high Young’s modulus and tensile strength.

Ramalan teori sifat tegangan CNT-CF/PP hibrid komposit telah dicapai dengan

menggunakan model hierarki yang terdiri daripada persamaan Halpin-Tsai,

Gabungan Voigt-Reuss model, mudah rule-of-mixture (RoM) dan pendekatan

Krenchel. Apabila geometri dalaman komposit adalah RoM faktor utama telah

digunakan untuk mengkaji pengagihan orientasi gentian dalam komposit. Satu

siasatan fractographic yang komprehensif telah dijalankan dengan mikroskop

imbasan elektron (SEM) untuk menganalisis taburan orientasi gentian patah CNT-

CF/PP permukaan komposit. Kemudian, analisis yang teliti telah dilakukan ke atas

imej SEM menggunakan Bersoft dan imej Geozebra menganalisis pakej perisian

untuk menilai faktor pengagihan orientasi gentian ( 0η ). Dalam konteks pendekatan

ini, apabila kesan orientasi gentian diabaikan sisihan yang patut diberi perhatian

dalam modulus tegangan dengan 51% telah dimaklumkan bukannya hasil

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eksperimen 1,72 GPa. Apabila dianggap pengesahan yang lebih diterima dengan

keputusan ujikaji modulus tegangan diperolehi yang menunjukkan sisihan sederhana

dengan 30% kepada nilai yang diramalkan 4,57 GPa. Akhirnya, perbezaan di antara

nilai-nilai yang diramalkan dan eksperimen telah dijelaskan dalam segi kelakuan

tegasan-terikan.

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ACKNOWLEDGEMENTS

I am heartily grateful to Allah S.W.T for giving me the potency and patience that

facilitates me to complete this thesis.

Here, I would like to convey my gratitude to my research advisor, Associate Professor

Dr. Suraya Abdul Rashid, for giving me the opportunity to join her research group, and

for her constant support, guidance, idea and encouragement throughout my research

program. Her expertise and knowledge in nanomaterials and nanotechnology will prove

to be priceless throughout the rest of my scientific career. I am also grateful to the other

committee member, Dr. Mohamad Amran Mohd Salleh for his useful suggestions,

criticisms and kind advices during my research period which helped me make this work

success.

Secondly, I would like to acknowledge the support from Department of Chemical and

Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia. I also

deeply appreciate the help given by the staff members of Material Science Lab,

Analytical Lab, and Strength of Materials Lab in Faculty of Engineering. I am glad to

receive their kind trust in handling the analytical instruments during the experimental

approaches.

Last but not least, I owe my sincere gratitude to my family, friends, and colleagues thus

far and everything yet to come, especially my wife, Bidita Binte Salahuddin, and my

sister, Khaleda Naznin for their priceless help, guidance, and endless encouragement and

blessing.

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I certify that a Thesis Examination Committee has met on 20 February 2013 to conduct the final examination of Shazed Md. Aziz on his thesis entitled "Experimental And Theoretical Evaluation of the Tensile Properties of Carbon Nanotube-Coated Carbon Fibre Hybrid Composites" in accordance with the Universities and University Colleges Act 1971 and the Constitution of the Universiti Putra Malaysia [P.U.(A) 106] 15 March 1998. The Committee recommends that the student be awarded the Master of Science. Members of the Thesis Examination Committee were as follows: Zulkiflle bin Leman, PhD Associate Professor Faculty of Engineering Universiti Putra Malaysia (Chairman) Thomas Choong Shean Yaw, PhD Professor Faculty of Engineering Universiti Putra Malaysia (Internal Examiner) Khamirul Amin b. Matori, PhD

Senior Lecturer Faculty of Science Universiti Putra Malaysia (Internal Examiner) Mohamad Rusop bin Haji Mahmood, PhD

Associate Professor Faculty of Electrical Engineering Universiti Teknologi Mara (UiTM) Malaysia (External Examiner)

SEOW HENG FONG, PhD Professor and Deputy Dean School of Graduate Studies Universiti Putra Malaysia Date:

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This thesis was submitted to the Senate of Universiti Putra Malaysia and has been

accepted as fulfillment of the requirement for the degree of Master of Science. The

members of the Supervisory Committee were as follows:

Suraya Abdul Rashid, PhD

Associate Professor

Faculty of Engineering

Universiti Putra Malaysia

(Chairman)

Mohamad Amran Mohd Salleh, PhD

Senior Lecturer

Faculty of Engineering

Universiti Putra Malaysia

(Member)

BUJANG BIN KIM HUAT, PhD

Professor and Dean

School of Graduate Studies

Universiti Putra Malaysia

Date:

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DECLARATION

I declare that the thesis is my original work except for quotations and citations which

have been duly acknowledged. I also declare that it has not been previously, and is

not concurrently, submitted for any other degree at Universiti Putra Malaysia or at

any other institution.

SHAZED MD. AZIZ

Date: 20 February 2013

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TABLE OF CONTENTS

Page

DEDICATION ii

ABSTRACT iii

ABSTRAK vi

ACKNOWLEDGEMENTS ix

APPROVAL x

DECLARATION xii

LIST OF TABLES xv

LIST OF FIGURES xvi

LIST OF ABBREVIATIONS xix

CHAPTER

1 INTRODUCTION 1 1.1 Background Study 1

1.2 Problem Statement 4

1.3 Objectives of Study 6

1.4 Scope of Work 7

1.5 Thesis Outline 8

2 LITERATURE RIVIEW 10 2.1 Carbon Fibre (CF) 10

2.2 Carbon Nanotubes (CNT) 12

2.3 CNT-coated CF 14

2.3.1 Chemical Vapor Deposition (CVD) 15

2.3.2 Floating Catalyst CVD Technique 16

2.3.3 Influence of Reaction Parameters 17

2.4 CF Reinforced Composite 19

2.4.1 Polymeric Matrix Resin 20

2.4.2 Randomly Oriented Short Fibre

Reinforced Composites 22

2.4.3 Effect of CNT Coating on CF 23

2.5 Properties of Hybrid Composites 25

2.5.1 Interfacial Properties 26

2.5.2 Tensile Properties 29

2.5.3 Fractured Surface 31

2.6 Theoretical Prediction of Hybrid Composite

Tensile Properties 33

2.6.1 Numerical Approaches 34

2.6.2 Fibre Orientation in the

Interior of Composite 37

2.7 Summary 39

3 METHODOLOGY 41

3.1 Introduction 41

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3.2 Fabrication and Characterization of

CNT-CF Hybrid Composites 42

3.2.1 Preparation of CNT-Coated CF 42

3.2.2 Preparation and Fragmentation Test

of CNT-Single CF Hybrid Composite 45

3.2.3 Preparation and Tensile Test of

CNT-CF Hybrid Composite 47

3.3 Application of Theoretical Model for Tensile

Properties of CNT-CF Hybrid Composite 51

3.3.1 Modeling Young’s Modulus 51

3.3.2 Hierarchical Approach to Model Based

Prediction of Hybrid Composite

Tensile Properties 54

4 RESULTS AND DISCUSSION 57

4.1 Introduction 57

4.2 Experimental Evaluation on the Effect of

CNT-Coating on the Tensile Properties

of CNT-CF Hybrid Composite 58

4.2.1 Morphology of CNT-Coated CF 58

4.2.2 CNT-CF Interfacial Properties

in Single Fibre Composite 64

4.2.3 Tensile Properties of CNT-CF

Hybrid composite 70

4.3 Theoretical Evaluation of the Effect of

CNT-Coating on the Tensile Properties

of CNT-CF Hybrid Composite 73

4.3.1 Model Based Prediction of CNT-CF

Hybrid Composite Tensile Properties 74

4.3.2 Validation of Theoretical Model 78

5 CONCLUSION AND FUTURE WORKS 82

5.1 Conclusions 82

5.2 Future Works 84

REFERENCES 86

APPENDIX 97

Properties of Commercial Carbon Fibre (CF) 98

Properties of Epoxy Matrix Resin 100

Properties of Polypropylene (PP) 102

Standard Test Method for Tensile Properties 103

BIODATA OF STUDENT 117

LIST OF PUBLICATION 118