universiti putra malaysia - connecting repositoriesconduct the final examination of intan syafinaz...
TRANSCRIPT
UNIVERSITI PUTRA MALAYSIA
INTAN SYAFINAZ MOHAMED AMIN TAWAKKAL
FK 2011 28
PREPARATION OF KENAF DERIVED CELLULOSE-FILLED POLYLACTIC ACID COMPOSITES
© COPYRIG
HT UPM
PREPARATION OF KENAF DERIVED
CELLULOSE-FILLED POLYLACTIC ACID
COMPOSITES
INTAN SYAFINAZ MOHAMED AMIN
TAWAKKAL
MASTER OF SCIENCE
UNVERSITI PUTRA MALAYSIA
2011
© COPYRIG
HT UPM
PREPARATION OF KENAF DERIVED CELLULOSE-FILLED
POLYLACTIC ACID COMPOSITES
By
INTAN SYAFINAZ MOHAMED AMIN TAWAKKAL
Thesis Submitted to the School of Graduates Studies, Universiti Putra Malaysia,
in Fulfilment of the Requirements for the Degree of Master of Science
February 2011
© COPYRIG
HT UPM
ii
DEDICATION
To my beloved mother, Rahimah Mahmud;
My loving brothers, Hafiz and Azhar;
My family members and friends.
Thanks for your encouragement, patience and loving support.
© COPYRIG
HT UPM
iii
Abstract of thesis presented to the Senate of Universiti Putra Malaysia in fulfilment
of the partial requirement for the degree of Master of Science
PREPARATION OF KENAF DERIVED CELLULOSE-FILLED
POLYLACTIC ACID COMPOSITES
By
INTAN SYAFINAZ MOHAMED AMIN TAWAKKAL
ER 2010
February 2011
Chair : Rosnita A. Talib, PhD
Faculty : Engineering
The aim of current research was to prepare kenaf derived cellulose (KDC)/polylactic
acid (PLA) composites. The KDC or α-cellulose was derived from kenaf bast fibre
(KBF) which was chemically treated via chlorination and mercerisation processes.
The characteristics of kenaf fibre and cellulose on the chemical, morphological and
physical properties were investigated by using FTIR, ESEM and density
measurements. Optimisation of the composite processing variables namely
temperature and time was carried out via RSM with respect to tensile strength and
stock temperature. The composites were compounded using internal mixer at fixed
KDC loading of 5 wt% and screw speed of 50 rpm in the temperature range of 160,
170 and 180°C for 10, 20 and 30 minutes. The effects of various KDC loadings (0-
60 wt%) on the chemical, mechanical, thermal and physical properties of the
KDC/PLA composites were also investigated.
© COPYRIG
HT UPM
iv
The cellulose was successfully derived from the KBF by removing of lignin and
hemicellulose. This was confirmed by the absence of these components from the
FTIR spectrum of the cellulose and the ESEM micrographs. From the ESEM
micrographs, the cellulose could be observed by its greater size reduction than the
raw fibre and rough surface topography. Meanwhile, the ANOVA statistical data
demonstrated that the tensile strength and stock temperature of the 5 wt% KDC/PLA
composites were affected mostly by mixing temperature with P < 0.0500. The
composites performed an optimum value at two combinations of variables which are
at 170°C for 20 minutes and 170°C for 30 minutes. Nevertheless, 170°C and 30
minutes was chosen as the best mixing conditions in order to produce composite at
higher KDC loading.
The FTIR spectrum of the KDC/PLA composite clearly indicated that no chemical
interaction was present between KDC and PLA matrix in the composite.
Interestingly, the incorporation of KDC into PLA matrix has demonstrated
remarkable improvement in the tensile strength and stiffness properties. The tensile
strength and modulus of KDC/PLA composite increased as the KDC loading
increased. The ESEM micrographs revealed evidence of good interfacial adhesion
between the KDC and PLA matrix and even distribution of the KDC in the
composite system. However, the effects of KDC loading on the flexural and notched
impact strength indicated that no remarkable changes were occurred in a range of 10
to 40 wt% of KDC loading.
The incorporation of the KDC into PLA matrix also improves the stiffness of
composite due to the enhancement of storage modulus as compared to the neat PLA.
© COPYRIG
HT UPM
v
The DMA results demonstrated that the storage modulus of the 60 wt% KDC/PLA
composite is twice higher than the neat PLA and the rest of the composites within a
high temperature range (above 80°C). The glass transition temperatures (Tg)
generated from the loss modulus curves exhibit that the peak was shifted to higher
temperature as the percentage of cellulose loading in the composites was increased.
Thus, the addition of KDC into the PLA matrix resulted better thermal stability and
exhibited effective reinforcing agent. The water absorption of the composites
increased with increasing KDC loading while the neat PLA absorbed lesser water.
The 60 wt% KDC/PLA composite demonstrated approximately 12% of water
uptake, which is considered as relatively low percentage of water absorption in
biocomposite.
© COPYRIG
HT UPM
vi
Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai
memenuhi keperluan untuk ijazah Master Sains
PENYEDIAAN KOMPOSIT SELULOSA TERBITAN DARIPADA KENAF
TERISI POLILAKTIK ASID
Oleh
INTAN SYAFINAZ MOHAMED AMIN TAWAKKAL
Februari 2011
Pengerusi : Rosnita A. Talib, PhD
Fakulti : Kejuruteraan
Tujuan penyelidikan ini adalah untuk menghasilkan komposit selulosa terbitan kenaf
(KDC) dengan polilaktik asid (PLA). KDC atau α-selulosa telah diterbitkan daripada
gentian batang kenaf (KBF) melalui proses rawatan kimia iaitu pengklorinan dan
pengalkalian. Ciri-ciri gentian kenaf dan selulosa terhadap sifat kimia, mofologikal
dan fizikal telah dikaji dengan menggunakan teknik seperti FTIR, ESEM dan ukuran
ketumpatan. Pengoptimuman pembolehubah-pembolehubah pemprosesan komposit
terutamanya suhu dan masa telah dijalankan terhadap kekuatan regangan dan suhu
terkumpul dengan menggunakan kaedah RSM pada peratusan kandungan KDC
sebanyak 5 wt% dan kelajuan skrew sebanyak 50 rpm dengan menggunakan
pengadun pada julat suhu 160, 170 dan 180°C untuk 10, 20 dan 30 minit. Kesan-
kesan komposit bagi pelbagai peratusan kandungan KDC terhadap sifat kimia,
mekanikal, termal dan fizikal turut dikaji.
© COPYRIG
HT UPM
vii
Terbitan selulosa daripada KBF telah berjaya dihasilkan melalui penyingkiran lignin
dan hemisellulosa. Penyingkiran ini disahkan dengan ketiadaan komponen-
komponen tersebut di dalam spektrum FTIR selulosa dan mikrograf ESEM. Melalui
mikrograf ESEM, didapati selulosa memiliki garis pusat yang lebih kecil
berbandingan gentian kenaf dan topografi permukaan selulosa yang kasar telah
diperolehi. Selain itu, berdasarkan data statistik ANOVA, didapati hubungan
diantara kekuatan regangan dan suhu terkumpul terhadap pembolehubah komposit
adalah amat dipergaruhi oleh suhu pengadun dengan P < 0.0500. Komposit-
komposit ini juga menghasilkan nilai optimum pada dua kombinasi pembolehubah
iaitu pada 170°C dan 20 minit serta 170°C dan 30 minit. Bagaimanapun, 170°C dan
30 minit adalah kombinasi pembolehubah yang paling sesuai bagi menghasilkan
komposit pada peratusan kandungan KDC yang lebih tinggi.
Spektrum FTIR komposit secara jelas menunjukkan tiada interaksi kimia yang
wujud diantara KDC dan matrik PLA. Menariknya, penggabungan KDC di dalam
matrik PLA telah menunjukkan peningkatan kekuatan regangan dan ketegaran
komposit yang memberangsangkan. Kekuatan dan modulus regangan juga
meningkat dengan penambahan peratusan kandungan KDC. Mikrograf ESEM
komposit pada permukaan patah kekuatan regangan membuktikan kewujudan
lekatan yang baik diantara KDC dan matrik PLA serta taburan KDC yang sekata di
dalam sistem komposit. Walau bagaimanapun, sifat komposit terhadap kekuatan
lenturan dan impak menunjukkan tiada perubahan ketara berlaku pada peratusan
kandungan KDC dari 10 hingga 40%.
© COPYRIG
HT UPM
viii
Penggabungan KDC di dalam matrix PLA juga menambahkan ketegaran komposit.
Ini disebabkan oleh peningkatan modulus simpanan komposit apabila dibandingkan
dengan PLA tulen. Pada suhu yang tinggi (lebih 80°C), ujian DMA menunjukkan
modulus simpanan komposit pada 60% kandungan KDC adalah dua kali lebih tinggi
berbanding PLA dan komposit-komposit lain. Manakala, suhu peralihan kaca (Tg)
yang diperoleh melalui lengkungan modulus lesapan menunjukkan berlakunya
anjakan puncak ke suhu yang lebih tinggi dengan penambahan peratusan kandungan
KDC. Oleh itu, penambahan KDC ke dalam matrix PLA telah menghasilkan
kestabilan termal yang lebih baik serta membuktikan keberkesanan selulosa sebagai
agen penguat. Penyerapan air terhadap komposit didapati semakin meningkat
dengan penambahan peratusan kandungan KDC. Komposit yang mengandungi 60%
kandungan KDC menunjukkan kadar penyerapan air sebanyak 12%. Peratusan ini
bagaimanapun adalah agak rendah di dalam biokomposit.
© COPYRIG
HT UPM
ix
ACKNOWLEDGEMENTS
All praises be to the Mighty Allah S.W.T, the Merciful and the Beneficent for the
strength, patience, determination and blessing in the completion of this study. It is
impossible for me to finish this thesis all by myself without the guidance and help of
many important people.
Firstly, for the preparation of this thesis and the well going for this project, I wish to
express my acknowledgement to my main supervisor, Dr. Rosnita A. Talib who
guide me continuously and patiently reviewed this thesis. I had been receiving
invaluable guidance, encouragement and constructive criticism from my supervisor.
She has been my advisor throughout my graduate education. I would like to thank
my co-supervisor Dr. Khalina Abdan, who has been very supportive and helpful
especially during the preparation of my samples and thesis. I also appreciate her
guidance and support in supervising me. Not forgotten, my appreciation to Mr.
Khalid from International Islamic University Malaysia, (IIU) for his guidance and
help in sharing valuable experience and knowledge regarding this research.
Appreciation and thanks are also dedicated to all the staff and technicians in
Radiation Processing Technology Division, Malaysian Nuclear Agency (MNA),
Department of Food and Process Engineering UPM, Department of Chemical and
Environmental Engineering UPM and Laboratory of Biocomposite Technology,
Institute of Tropical Forestry and Forest Products (INTROP), especially to Mr.
Faizal, Mr. Bernard, Mr. Falah, Mrs. Siti Hajar, Mr. Raman, Mr. Zahir, Mr. Shah,
Mr. Ismail Abdul Ghani and Ms. Hasniza. A special thanks goes to Mr. Wan Ali,
© COPYRIG
HT UPM
x
staff of MNA for his assistance during the preparation of samples and sharing his
outstanding knowledge. Thank you for your help and assistance throughout the
experimental work. Beside that, I would like to thank PhD students, Mrs. Behjat
Tajeddin from UPM and Mrs. Aishah @ Min Min Aung from UKM for their
encouragement and willingness in sharing experience. To INTROP’s students Ipin,
Mai, Jue and Eda thank you for your time, help and guidance.
Also last but not least, a special thanks to my family especially my beloved mother,
brothers and sister for their encouragements, patience and moral support in
completing this study. To all of my friends and colleagues especially, Faridah,
Norazlin, Nurul Lina, So’bah, Awanis, Aziana, Rohaiza, Zafirah, Che Rodiziah,
Aishah, Roazita, Intan Shidatul, Chui Yen, Hamidah and my peer group (Norma,
Siti Hajar, Faezah and Zuhair) for being supportive with their kindness and co-
operations all the way. Your supports and encouragements mean a word to me.
Thanks a lot to you all. I could not have completed this thesis without each of you.
© COPYRIG
HT UPM
xi
I certify that a Thesis Examination Committee has met on 24 February 2011 to
conduct the final examination of Intan Syafinaz Mohamed Amin Tawakkal on her
thesis entitle “Preparation of Kenaf Derived Cellulose-Filled Polylactic Acid
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:
Russly bin Abdul Rahman, PhD
Professor
Faculty of Engineering
Universiti Putra Malaysia
(Chairman)
Yus Aniza binti Yusof, PhD
Senior Lecturer
Faculty of Engineering
Universiti Putra Malaysia
(Internal Examiner)
Mohd Nordin bin Ibrahim, PhD
Associate Professor
Faculty of Engineering
Universiti Putra Malaysia
(Internal Examiner)
Rozman bin Din, PhD
Professor
School of Industrial Technology
Universiti Sains Malaysia
(External Examiner)
______________________________
ZULKARNAIN ZAINAL, PhD Professor and Deputy Dean
School of Graduate Studies
Universiti Putra Malaysia
Date:
© COPYRIG
HT UPM
xii
This thesis was submitted to the Senate of Universiti Putra Malaysia and has been
accepted as fulfilment of the requirement for the degree of Master of Science. The
members of the Supervisory Committee were as follows:
Rosnita A. Talib, PhD
Senior Lecturer
Faculty of Engineering
Universiti Putra Malaysia
(Chairman)
Khalina Abdan, PhD
Senior Lecturer
Faculty of Engineering
Universiti Putra Malaysia
(Member)
________________________________
HASANAH MOHD GHAZALI, PhD
Professor and Dean
School of Graduate Studies
Universiti Putra Malaysia
Date:
© COPYRIG
HT UPM
xiii
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.
_____________________________
INTAN SYAFINAZ MOHAMED
AMIN TAWAKKAL
Date: 24 February 2011
© COPYRIG
HT UPM
xiv
TABLE OF CONTENTS
Page
DEDICATION ii
ABSTRACT iii
ABSTRAK vi
ACKNOWLEDGEMENTS ix
APPROVAL xi
DECLARATION xiii
LIST OF TABLES xvi
LIST OF FIGURES xvii
LIST OF ABBREVIATIONS xx
CHAPTER
1 INRODUCTION
1.1 Background 1
1.2 Research Objectives 5
1.3 Outline of the Thesis 5
2 LITERATURE REVIEW
2.1 Introduction 7
2.2 Biodegradable Polymers 8
2.3 Polylactic Acid (PLA) 9
2.4 PLA as Bio-based Packaging Materials 12
2.5 Plant Fibres and Biocomposites 15
2.6 Natural Fibres Reinforced Biopolymers 17
2.7 Kenaf (Hibiscus Cannabinus L.) 19
2.8 Lignocellulosic Fibres Structure 21
2.9 Modification of Natural Fibres 24
2.10 Mercerisation 25
2.11 The Characteristics of Short Fibres
2.11.1 Fibres/Matrix Adhesion and Interaction 27
2.11.2 Fibres Aspect Ratio 28
2.11.3 Fibres Volume Fraction 29
2.11.4 Fibres Distribution 30
2.12 Mixing Torque Curve 32
2.13 Respond Surface Method (RSM) 34
2.14 FTIR Spectroscopy 35
2.15 The Mechanical Properties 36 2.16 The Thermal Properties 41
2.17 The Physical Properties 43
3 METHODOLOGY
3.1 Introduction 46
3.2 Materials 46
3.3 The Preparation of the Cellulose from Kenaf Bast Fibre 48
3.4 The Experimental Design of the Optimisation of Processing
Variables 49
3.5 The Preparation of the Composites 51
3.6 The Preparation of the Testing Specimens 52
© COPYRIG
HT UPM
xv
3.7 Testing and Characterisation Procedures
3.7.1 FTIR Spectra Analysis 53
3.7.2 Mechanical Properties Testing 53
3.7.3 Dynamic Mechanical Analysis 54
3.7.4 Characterisation of Physical Properties 55
3.7.5 ESEM Micrograph Analysis 56
4 CHARACTERISTICS OF KENAF FIBRE AND CELLULOSE
4.1 Introduction 57
4.2 The Properties of Kenaf Fibre and Cellulose
4.2.1 FTIR Spectra 57
4.2.2 Morphology Analysis 58
4.2.3 Bulk Density 60
4.3 Discussions 61
4.4 Summary 64
5 OPTIMISATION OF THE MIXING VARIABLES
5.1 Introduction 65
5.2 The RSM of Processing Variables
5.2.1 Statistical Analysis and Response Surface on
Tensile Strength 66
5.2.2 Statistical Analysis and Response Surface on
Stock Temperature 70
5.2.3 Overlay between Responses 73
5.3 Discussions 74
5.4 Summary 79
6 EFFECTS OF THE KDC LOADING
6.1 Introduction 80
6.2 Properties of the KDC/PLA Composites
6.2.1 Fourier Transmission Infrared Spectra 80
6.2.2 Tensile Properties 82
6.2.3 Flexural Properties 84
6.2.4 Notched Izod Impact Strength 85
6.2.5 Dynamic Mechanical Analysis (DMA) 86
6.2.6 Water Absorption 90
6.2.7 Density 91
6.2.8 Morphology Analysis 91
6.3 Discussions 92
6.4 Summary 110
7 CONCLUSIONS AND RECOMMENDATIONS
7.1 Introduction 111
7.2 Summary of the Study 111
7.3 Recommendations for Future Work 113
REFERENCES 115
APPENDICES 130
BIODATA OF STUDENT 148
LIST OF PUBLICATIONS 149