UNIVERSITI PUTRA MALAYSIA

SHARMEEN BINTI ADNAN

FK 2011 123

IMPREGNATION OF IN-HOUSE SYNTHESIZED CARBON NANOTUBES INBACTERIAL CELLULOSE

© COPYRIG

HT UPM

IMPREGNATION OF IN-HOUSE SYNTHESIZED CARBON NANOTUBES IN BACTERIAL CELLULOSE

By

SHARMEEN BINTI ADNAN

Thesis Submitted to the School of Graduated Studies, Universiti Putra Malaysia, in Fulfillment of the Requirement for the Degree of Master of Science

August 2011

© COPYRIG

HT UPM

ii

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

requirement for the degree of Master of Science.

IMPREGNATION OF IN-HOUSE SYNTHESIZED CARBON NANOTUBES IN BACTERIAL CELLULOSE

By

SHARMEEN BINTI ADNAN

August 2011

Chair: Dayang Radiah Bt. Awang Biak, PhD

Faculty: Faculty of Engineering

Bacterial cellulose (BC) synthesized by Acetobacter xylinum has been discovered as a potential

matrix for impregnating carbon nanotubes (CNT). The main objective of this study is to

produce bacterial cellulose/carbon nanotube (BC/CNT) with improved hydrophobic surface.

CNT addition is by mean to improve the electrical property of BC to be a conductive

membrane. Hydrophobic membrane is more practical in device development since it can adhere

with other hydrophobic material, which is achieved in this study by acetylation process. In this

work, the membranes were produced using date extract (DE) culture medium. Three CNT

impregnation techniques were tested, i.e. immersion, dispersion and spraying, whilst the

acetylation conducted were homogeneous and heterogeneous processes.

© COPYRIG

HT UPM

iii

In this study, morphological characteristic is an important property for sample selection to be

characterized further. BC/CNT nanocomposite produced via spraying technique has uniform

CNT dispersion and has the most dielectric conductivity value i.e. ~4.66 x 10-1 S/cm than the

other techniques. Therefore, spraying was used to prepare BC/CNT acetate nanocomposite.

Since the morphology of BC/CNT acetate obtained from heterogeneous process proves that the

acetylation only occurred on the surface and the inner core structures of the BC are still intact,

this process was used further.

The most significant characteristic of BC/CNT acetate is the existence of C=O, CH3 and C-O

functional groups of acetyl and higher water contact angle (~77°) than that of BC/CNT (~45°).

When tested, decomposition and glass transition temperatures of BC/CNT acetate have reduced

by 203°C and 35°C respectively, compared to that BC/CNT. The reduction is occurred mainly

because the swollen BC structure of BC/CNT acetate is easily degraded by heat treatment.

The acetylated BC/CNT on the other hand, has higher crystal BC fraction, i.e. 51% compared to

that of BC/CNT (49%). These findings indicate that the CNT hinders the degradation of

nanocomposite and protects the BC crystals. Thus when acetylated, both elasticity and

crystallite size of BC/CNT has only reduced by 9%, i.e., from 34 to 31 GPa and from 27.3 to

24.9 nm, respectively. The bigger pore size of the acetate nanocomposite (~22 Å) than that of

BC/CNT (~-103 Å) might allows further functionalization process introduced to the membrane.

As a conclusion, the CNT impregnation by spraying technique during the growing fermentation

of BC coupled with heterogeneous acetylation treatment resulted in a more water resistant,

© COPYRIG

HT UPM

iv

increased dielectric conductivity and increased crystal BC fraction. While, the sheet elasticity,

crystallite size, surface area, decomposition and glass transition temperatures became lower.

These characteristics makes acetylated BC/CNT sheet a potential as a biomaterial membrane in

device development.

© COPYRIG

HT UPM

v

Abstrak tesis yang dikemukan kepada Senat Universiti Putra Malaysia sebagai memenuhi

keperluan untuk Ijazah Master Sains.

IMPREGNASI NANOTIUB KARBON YANG DISINTESIS SECARA DALAMAN KE

DALAM SELULOSA BAKTERIA

Oleh

SHARMEEN BINTI ADNAN

Ogos 2011

Pengerusi: Dayang Radiah Bt. Awang Biak, PhD

Fakulti: Fakulti Kejuruteraan

Selulosa bakteria (BC) yang disintesis oleh Acetobacter xylinum telah dikenalpasti sebagai

matriks yang berpotensi tinggi untuk diisi dengan nanotiub karbon (CNT). Objektif utama

penyelidikan ini adalah untuk menghasilkan nano-komposit selulosa bakteria/nanotiub karbon

(BC/CNT) dengan permukaan hidrofobik. CNT ditambahkan bagi memperbaiki ciri elektrikal

BC seterusnya menghasilkan membran yang konduktif. Membran yang hidrofobik pula lebih

praktikal dalam penghasilan peralatan kerana ia lebih sesuai untuk digunakan bersama bahan

hidrofobik yang lain. Dalam penyelidikan ini, membran dihasilkan menggunakan media kultur

daripada ekstrak kurma. Tiga teknik impregnasi CNT yang dijalankan adalah rendaman,

© COPYRIG

HT UPM

vi

serakan dan semburan manakala proses asetilasi pula adalah proses asitilasi penuh dan asitilasi

separa.

Dalam kajian ini, morfologi adalah ciri penting dalam pemilihan sampel yang akan dianalisa

sepenuhnya. Nano-komposit BC/CNT yang dihasilkan melalui teknik semburan menunjukkan

keseragaman penyebaran CNT serta mempunyai nilai konduktiviti di-elektrik yang paling baik

iaitu ~4.66x 10-1 S/cm berbanding nilai yang ditunjukkan oleh BC/CNT yang dihasilkan melalui

teknik-teknik yang lain. Maka, teknik semburan telah digunakan untuk menghasilkan nano-

komposit BC/CNT asetat. Disebabkan morfologi BC/CNT asetat yang disediakan melalui

proses asitilasi separa menunjukkan degradasi hanya berlaku di permukaan sahaja sementara

struktur teras dalam BC tidak terjejas, maka proses ini digunakan untuk penghasilan sampel

seterusnya.

Ciri BC/CNT asetat dikenalpasti melalui kewujudan ikatan-ikatan yang mewakili kumpulan

berfungsi asetil iaitu C=O, CH3 dan C-O dan juga nilai sudut antara air dan BC/CNT asetat

yang lebih tinggi (~77°) berbanding BC/CNT (~45°). Apabila kedua-duanya dikaji, suhu

penguraian dan peralihan kaca bagi BC/CNT asetat menurun kepada 203°C dan 35°C, masing-

masing. Penurunan ini berlaku kerana struktur BC dalam BC/CNT asetat yang membengkak

memudahkannya diuraikan dengan rawatan suhu.

© COPYRIG

HT UPM

vii

Namun begitu, BC/CNT asetat mempunyai kandungan hablur BC yang lebih tinggi, iaitu 51%

berbanding BC/CNT (49%). Ini menunjukkan CNT telah menghalang proses penguraian nano-

komposit seterusnya melindungi hablur BC. Disebabkan itu, kedua-dua keupayaan elastik dan

saiz hablur BC/CNT hanya menurun sebanyak 9% sahaja, iaitu daripada 34 ke 31 GPa dan

daripada 27.3 ke 24.9 nm, masing-masing. Tambahan pula, liang nano-komposit asetat yang

lebih besar (~22 Å) berbanding BC/CNT (~-103 Å) mungkin membolehkan proses

penambahbaikan fungsi dilakukan ke atas membran tersebut.

Kesimpulannya, impregnasi CNT melalui teknik semburan semasa fermentasi BC berlaku

disamping rawatan asetilasi separa telah menghasilkan membran yang rintang kepada air, tinggi

nilai konduktiviti dielektrik dan tinggi kandungan hablur BCnya. Namun, keupayaan elastik,

saiz hablur, suhu penguraian dan suhu peralihan kaca telah menurun. Ciri-ciri ini menjadikan

membran BC/CNT asetat berpotensi sebagai biomaterial membran dalam pembuatan peralatan.

© COPYRIG

HT UPM

viii

ACKNOWLEDGEMENT

“In the name of Allah S.W.T., the most Benevolent and Merciful.

All gratification is referred to Allah S.W.T.”

Firstly, I would like to take this opportunity to thank the chairperson of my supervisory

committee, Dr. Dayang Radiah Bt. Awang Biak, whose expert guidance and support has helped

me to complete the research. Her kindness, affection, encouragement and moral support gave

me the courage and ability to overcome all the problems I have faced from time to time during

the course of my work. I would like to extend my appreciation to her for the invaluable advice

and continuous comment and support, which brighten my future through the experiences that I

have gained from her.

I am also very grateful to Mrs. Faizah Bt. Md. Yasin, whose expert guidance and support has

helped me to overcome problems that I have encountered during the course of my study. I am

also indebted to and wish express my appreciation to Mrs. Suryani Bt. Kamaruddin for her

interest and invaluable suggestion that had enable me to carry on with my project successfully.

© COPYRIG

HT UPM

ix

I would like to thank Universiti Putra Malaysia for providing me a scholarship (Graduate

Research Fellowship) which has enables me to continue my research as well as my life a

student.

The list of thanks also goes to all my friends and the people who have known me for the joy,

laughter and memories that we have shared together during my study at Universiti Putra

Malaysia.

Lastly, I would like to express my most sincere and warmest gratitude to my mother (Siti

Hafsah Bt. Dahalan) and my father (Adnan B. Rajikan) and all my family members for their

payers, love, generosity and moral supports that they have during the course of my study.

© COPYRIG

HT UPM

x

I certify that a Thesis Examination Committee has met on 25 August 2011 to conduct the final examination of Sharmeen Binti Adnan on her thesis entitled "Impregnation of In-House Synthesized Carbon Nanotubes in Bacterial Cellulose" 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 degree of Master of Science. Members of the Thesis Examination Committee were as follows: Fakhru’l-Razi Ahmadun, PhD Professor Dr. Faculty of Engineering Universiti Putra Malaysia (Chairman) Robiah Yunus, PhD Professor Dr. Faculty of Engineering Universiti Putra Malaysia (Internal Examiner) Suraya Abdul Rashid, PhD Dr. Faculty of Engineering Universiti Putra Malaysia (Internal Examiner) Fadzilah Adibah Abdul Majid, PhD Associate Professor Dr. Department of Bioprocess Engineering, Faculty of Chemical Engineering Universiti Teknologi Malaysia Malaysia (External Examiner)

SEOW HENG FONG, PhD

Professor and Deputy Dean School of Graduate Studies Universiti Putra Malaysia

Date: 20 December 2011

© COPYRIG

HT UPM

xi

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: Dayang Radiah Bt. Awang Biak, PhD Senior Lecturer Faculty of Engineering Universiti Putra Malaysia. (Chairman) Faizah Bt. Md. Yasin Lecturer Faculty of Engineering Universiti Putra Malaysia. (Member)

_________________________________ BUJANG BIN KIM HUAT, PhD Professor and Dean School of Graduate Studies Universiti Putra Malaysia Date:

© COPYRIG

HT UPM

xii

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.

___________________________ SHARMEEN BINTI ADNAN Date: 25 August 2011

© COPYRIG

HT UPM

xiii

TABLE OF CONTENTS

Page

ABSTRACT ii ABSTRAK v ACKNOWLEDGEMENT viii APPROVAL x DECLARATION xii LIST OF TABLES xvii LIST OF FIGURES xviii LIST OF ABBREVIATIONS xxi

CHAPTER

1. INTRODUCTION 1

2. LITERATURE REVIEW 6

2.0 Introduction 6

2.1 Bacterial cellulose (BC) 6

2.1.1 Growth associate product of BC 7

2.1.2 Carbon source as crucial nutrient 9

2.1.3 Oxygen dependent of BC production 13

2.1.4 Crystal structure of BC microfibrils 13

2.1.5 BC nanocomposites 17

2.2 Carbon nanotubes (CNT) and bacterial cellulose/ 20

carbon nanotubes (BC/CNT) nanocomposites

2.2.1 Previous researches on BC/CNT nanocomposites 22

2.2.2 Dielectric properties of BC/CNT nanocomposites 23

2.3 Acetylation of BC and BC/CNT membranes 26

2.3.1 Mechanism of acetylation 27

2.3.2 Methodology of acetylation 27

2.4 Characterization of BC and BC/CNT membranes 29

2.4.1 Morphological analysis 29

© COPYRIG

HT UPM

xiv

2.4.2 Spectroscopic identification 30

2.4.3 Thermal characteristic 31

2.4.4 Mechanical characteristic 32

2.4.5 Surface analysis 33

2.4.5.1 Wettability 33

2.4.5.2 Surface area and porosity 34

2.5 Conclusion 34

3. METHODOLOGY 35

3.0 Introduction 35

3.1 Preparation of date extract (DE) 37

3.2 Culture medium preparation from DE 37

3.3 Production of BC membrane 38

3.4 Recovery process of BC membrane 39

3.5 Sample preparation for characterization 39

3.6 Experiment for carbon source selection 40

3.7 Production of BC/CNT membrane 40

3.7.1 (A) Immersing BC membrane in CNT 41

dispersed solution

3.7.2 (B) Dispersing CNT in DE culture medium 42

3.7.3 (C) Spraying CNT dispersed solution onto growing BC 42

(a) Preparation of DE culture medium and 42

CNT dispersed solution

(b) Spraying procedure of CNT dispersed solution 43

3.8 Dielectric conductivity calculation of BC/CNT membranes 44

3.9 Preparation of BC/CNT acetate nanocomposite 45

3.9.1 Homogeneous acetylation 45

3.9.2 Heterogeneous acetylation 46

3.10 Characterization of BC and nanocomposite membranes 47

3.10.1 Morphological observation 47

3.10.2 Spectroscopic identification 47

© COPYRIG

HT UPM

xv

3.10.3 Crystallinity analysis 48

3.10.4 Thermal analysis 49

3.10.5 Mechanical analysis 49

3.10.6 Surface wettability analysis 50

3.10.7 Surface area and porosity analysis 50

3.11 Conclusion 51

4. RESULTS AND DISCUSSION 52

4.0 Introduction 52

4.1 Comparison of the BC produced from HS and DE media 53

4.2 Production of BC/CNT nanocomposites 58

4.2.1 CNT dispersion behavior within BC membrane 58

(A) Immersing BC membrane in CNT 59

dispersed solution

(B) Dispersing CNT in BC culture medium 60

(C) Spraying CNT dispersed solution 62

onto growing BC

4.2.2 Physical characteristic of BC/CNT nanocomposites 64

4.2.3 Dielectric conductivity of the produced BC/CNT 66

4.3 Production of BC/CNT acetate nanocomposite 69

4.3.1 Physical changes of BC and BC/CNT due to acetylation 70

(A) Homogeneous acetylation 71

(B) Heterogeneous acetylation 73

4.4 Morphological observation 74

4.4.1 Character of BC produced using DE culture medium 74

4.4.2 Character of BC/CNT nanocomposites 75

(A) Immersing BC membrane in CNT 75

dispersed solution

(B) Dispersing CNT in DE culture medium 76

(C) Spraying CNT dispersed solution onto growing BC 78

4.4.3 Morphological changes of BC and BC/CNT acetates 79

© COPYRIG

HT UPM

xvi

4.5 Spectroscopic identification 82

4.5.1 The significant functional groups of the membranes 83

4.5.2 Determination of cellulose crystals via FTIR analysis 87

4.6 Crystallinity analysis 89

4.6.1 Crystalline peaks of the membranes 90

4.6.2 Determination of crystallite size 92

4.6.3 Determination of crystallinity index (CrI) 94

4.7 Thermal analysis 96

4.7.1 Weight loss percentage of the membranes 97

4.7.2 Determination of decomposition temperature 98

4.8 Mechanical analysis 100

4.8.1 Elasticity of the membranes 101

4.8.2 Viscous dissipation of the membranes 102

4.8.3 Determination of glass transition temperature (Tg) 103

4.9 Surface wettability analysis 104

4.10 Surface area and porosity analysis 106

4.10.1 Pore size investigation 107

4.10.2 Determination of surface area 109

4.11 Conclusion 111

5. SUMMARY, CONCLUSION AND 113

RECOMMENDATIONS FOR FUTURE RESEARCH

REFERENCES 117

APPENDICES 130

BIODATA OF STUDENT 136