DEVELOPMENT AND CHARACTERIZATION OF PLASTICIZED POLYLACTIC ACID BIOCOMPOSITE WITH DURIAN SKIN FIBRE FOR FOOD PACKAGING
SITI MUNIRAH SALIMAH BINTI ABD RASHID
A thesis submitted in fulfilment of the requirement for the degree of Master of Science (Materials Engineering)
Kulliyyah of Engineering
International Islamic University Malaysia
Disposable food packaging materials are mainly made from petroleum-based polymers, which give rise to landfill problems as they are not biodegradable. To overcome this issue, a biodegradable material such as polylactic acid (PLA) can be used as an alternative. The aim of this research was to develop biodegradable food packaging containers made from a PLA biocomposite reinforced with durian skin fibre (DSF). However, since the application of PLA is restricted by its brittleness, therefore, epoxidized palm oil (EPO) was added as a plasticizer to improve the flexibility of PLA. A PLA biocomposite with 30 wt.% DSF and 5 wt.% EPO was extruded and injection moulded for testing and characterization. The effects of EPO on the chemical, mechanical, morphological, thermal, physical and biodegradation properties of the PLA/DSF biocomposite were studied. Then, life cycle assessment (LCA) was investigated to study the effect on environment. The C-O-C stretching from the oxirane vibrations in the Fourier transform infrared (FTIR) spectroscopic analysis revealed the presence of EPO in the PLA/DSF biocomposite. The mechanical test proved that the incorporation of EPO enhanced the tensile, flexural and impact strength by approximately 6 to 37%. The elongation at break improved by up to 70%, showing that the EPO imparted flexibility to the PLA/DSF biocomposite. The SEM micrograph showed there was good compatibility between DSF and PLA and the ductile surface in the presence of EPO. The thermogravimetric analysis (TGA) results showed that the degradation temperature for the PLA/DSF biocomposite was 289 °C, while for the PLA/DSF/EPO biocomposite was 300 °C, hence suggesting that EPO contributed to the heat resistance of the biocomposite. From the differential scanning calorimetry (DSC) results, it was found that the addition of EPO had a plasticizing effect, where it reduced the glass transition temperature (Tg) of the biocomposite from 61 to 59 °C. The crystallization temperature (Tc) was also reduced from 125 to 105 °C, indicating that EPO accelerated the crystallization of the PLA/DSF biocomposite. The storage modulus of the plasticized PLA/DSF biocomposite was lowered as it become less stiff. A soil burial test indicated that the PLA/DSF/EPO biocomposite possessed a faster biodegradation rate and was almost fully biodegraded at 83% at 90 days. This could have been due to the high level of water absorption with 14% and changes to the dimensional stability of the biocomposite as the water penetrated into the PLA matrix. A life cycle assessment indicated that the PLA/DSF biocomposite had a major negative impact on the environment in terms of the global warming potential (GWP) about 198 kg CO2 eq. The other impacts on the environment were with regard to the eutrophication potential (EP), acidification potential (AP) and ozone layer depletion potential (ODP) with impact score 9 kg P eq., 0.7 kg SO2 eq. and 1 x 1011 kg CFC-11 eq., respectively. These impacts were mainly brought about by the usage of electricity, which contributed to the emission of CO2. However, the PLA/DSF/EPO biocomposite had lower negative impacts because EPO improved the workability and processability of the biocomposite, and hence, reduced the amount of energy required for production. It can be concluded that the cradle-to-cradle plasticized PLA/DSF biocomposite can be a potential biodegradable food packaging material as it has favourable properties and produces no waste.
ABSTRACT IN ARABIC
لىإ يدؤت تيلاو ، طفنلا ىلع ةمئاقلا تارميلوبلا نم اهنم صلختلا نكيم تيلا ةيئاذغلا داولما فيلغت داوم عينصت متي يساسأ لكشب نلأ تايافنلا نفد عقوم في لكاشم داولما هذه
ةلباق ةدام ليدبك مادختسا نكيم ، ةلكشلما هذه ىلع بلغتلل .للحتلل ةلباق يرغ
ضحم لثم للحتلل كيتكلايلوبلا
(PLA) ةيئاذغلا داولما فيلغت تايواح ريوطتل ثحبلا اذه فدهي . ةلباق
يويلحا للحتلل ةعونصمو
ةيجولويبلا كيتكلايلوبلا ضحم تابكرم نم نايرودلا دلج فايلأب ةززعلماو
( DSF قيبطت نلأ اًرظنو ، كلذ مغرو .) كيتكلايلوبلا ضحم
شاشه ببسب ديقم ضملحا ة
يديسكوبلإا ليخنلا تيز ةفاضإ تتم دقف ، (epoxidized palm oil)
مك ةنورم ينسحتل نّدل
كيتكلايلوبلا ضحم .
بكرم جارخإ تم عم كيتكلايلوبلا ضحم
30 نم ٪ يلأ ا نايرودلا دلج ف و
5 تيز نم ٪ ،يديسكوبلإا ليخنلا
فيصوتلاو رابتخلال بلاقلا نقح تمو .
يديسكوبلإا ليخنلا تيز رثآ ةسارد تتم ةيجولوفرولماو ةيكيناكيلماو ةيئايميكلا صاولخا ىلع
صالخا يويلحا للحتلل ةيجولويبلاو ةيئايزيفلاو ةيرارلحاو ضمبح
، نايرودلا دلج فايلأو كيتكلايلوبلا و
يلحا ةرود مييقت صحف تم ةا
( life cycle assessment )
دادتما ليلتح فشك .ةئيبلا ىلع يرثأتلا ةساردل C-O-C
ليوتح في نايرسكلأا تازازتها نم
ءارملحا تتح ةعشلأاب فيطلل هييروف (FTIR)
دوجو نع يديسكوبلإا ليخنلا تيز
ب صالخا يويلحا بيكترلا في PLA /
DSF جمد نأ يكيناكيلما رابتخلاا تبثأ . خنلا تيز
يديسكوبلإا لي دشلا ةوق ززع دق
و ، ءاننحلاا و لياوبح مادطصلاا 6
لىإ 37 .٪
امك نستح ت لىإ لصت ةبسنب ةحاترسلاا دنع ةلاطتسلاا 70
نأ ىلع لدي امم ، ٪ يديسكوبلإا ليخنلا تيز
في ةنورم ىطعأ دق
ب صالخا يويلحا بيكترلا PLA / DSF
الما نيوتركللإا رهجملل ةيرهلمجا ةروصلا ترهظأ . حس
SEM ينب ديج قفاوت دوجو
DSF و PLA و طسلا ح بحسلل لباقلا يرارلحا يعونلا لقثلا سايقم ليلتح جئاتن تحضوأ .يديسكوبلإا ليخنلا تيز دوجو في
(TGA) يويلحا بكرملل للحتلا ةرارح ةجرد نأ
PLA / DSF تناك
289 يويلحا بيكترلا نأ ينح في ، ةيوئم ةجرد
PLA / DSF / EPO
ناك 300 نأ لىإ يرشي امم ، ةيوئم ةجرد يديسكوبلإا ليخنلا تيز
بكرملل ةيرارلحا ةمواقلما في مهاس
نييابتلا حسلما رعسم جئاتن ترهظأ .يويلحا (differential scanning calorimetry)
ةفاضإ نأ ليخنلا تيز
لإا يديسكوب جاجزلا لاقتنا ةرارح ةجرد تضفخ ثيح ، نِّدل م يرثأت هل ناك
g) (T نم يويلحا بيكترلا في 61
لىإ 59 .ةيوئم ةجرد
رولبتلا ةرارح ةجرد ضيفتخ تم هنأ امك
c) نم اًضيأ(T 125 لىإ 105 نأ لىإ يرشي امم ، ةيوئم ةجرد يديسكوبلإا ليخنلا تيز
بيكترلا ةرولب في عراس ب صالخا يويلحا
PLA / DSF يويلحا بكرلماب صالخا نيزختلا لماعم ضيفتخ تم .
PLA / DSF
ةبلاص لقأ حبصأ هنلأ ندللما .
ـلل يويلحا بيكترلا نأ لىإ ةبترلا نفد رابتخا راشأ PLA / DSF / EPO
للتح لدعم كلتيم
عرسأ يجولويب دق هنأو ،
للتح ًلاماك ةبسنب اًبيرقت اًيجولويب 83
في ٪ ءالما صاصتما ىوتسم عافترا ببسب نوكي دق اذه .اًموي 90
ةبسنب 14 نأ لىإ ةايلحا ةرود مييقت راشأ .كيتكلايلوبلا ضحم ةفوفصلم هايلما قاترخا عم يويلحا بيكترلا داعبأ رارقتسا في تايرغتلاو ٪
ـلل يويلحا بيكترلا PLA / DSF
إب قلعتي اميف ةئيبلا ىلع يربك بيلس يرثأت هل ناك يلماعلا راترحلاا ثودح ةيلامتح
لياوبح 198 فيترتلا ةيلامتحإب ةقلعتم ةئيبلا ىلع ىرخلأا تايرثأتلا تناكو .نوبركلا ديسكأ نياث ئفاكم نم مجك ( EP)
ضيمحتلا ةيلامتحإ (AP)
و نوزولأا ةقبط دافنتسا ةيلامتحإ (ODP)
يرثأت ةجرد عم 9
مجك ئفاكم نم P
، 0.7 م مجك
فاكم ئ SO2
، و 1
11 × 10 تابكرم نم مجك 11
- CFC قيرط نع يسيئر لكشب راثلآا هذه تأشن دقو .لياوتلا ىلع ،
نوبركلا ديسكأ نياث ثاعبنا في مهاس امم ، ءابرهكلا مادختسا .
يويلحا بكرملل ناك ، كلذ عمو PLA / DSF / EPO
نلأ لقأ ةيبلس تايرثأت يديسكوبلإا ليخنلا تيز
ح نِم نَّس ةقاطلا ةيمك نم للق لياتلابو ،يويلحا بكرملل عينصتلاو ليغشتلا ةيلباق
ندللما يويلحا بيكترلا نأ لىإ جتنتسن نأ نكيم .جاتنلإل ةبولطلما PLA / DSF
يئاذغلا فيلغتلل ةلمتمح ةدام نوكي نأ نكيم
تايافن يأ هنع جتني لاو ةمئلام صئاصخ ىلع يوتيح هنأ ثيح للحتلل لباقلا .
I certify that I have supervised and read this study and that in my opinion, it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a thesis for the degree of Master of Science (Materials Engineering)
Hazleen Anuar Supervisor
Yose Fachmi Buys Co-Supervisor 1
Noor Azlina Hassan Co-Supervisor 2
I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a thesis for the degree of Master of Science (Materials Engineering)
Noorasikin Samat Internal Examiner
Hazizan Md. Akil External Examiner
This thesis was submitted to the Department of Manufacturing and Materials Engineering and is accepted as a fulfilment of the requirement for the degree of Master of Science (Materials Engineering)
Mohamed Abd. Rahman
Head, Department of Manufacturing and Materials Engineering
This thesis was submitted to the Kulliyyah of Engineering and is accepted as a fulfilment of the requirement for the degree of Master of Science (Materials Engineering)
Ahmad Faris Ismail
Dean, Kulliyyah of Engineering
I hereby declare that this thesis is the result of my own investigations, except where otherwise stated. I also declare that it has not been previously or concurrently submitted as a whole for any other degrees at IIUM or other institutions.
Siti Munirah Salimah binti Abd Rashid
Signature ... Date ...
INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA
DECLARATION OF COPYRIGHT AND AFFIRMATION OF FAIR USE OF UNPUBLISHED RESEARCH
DEVELOPMENT AND CHARACTERIZATION OF
PLASTICIZED POLYLACTIC ACID BIOCOMPOSITE WITH DURIAN SKIN FIBRE FOR FOOD PACKAGING APPLICATION
I declare that the copyright holders of this thesis are jointly owned by the student and IIUM.
Copyright © 2019 Siti Munirah Salimah binti Abd Rashid and International Islamic University Malaysia. All rights reserved.
No part of this unpublished research may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without prior written permission of the copyright holder except as provided below
1. Any material contained in or derived from this unpublished research may be used by others in their writing with due acknowledgement.
2. IIUM or its library will have the right to make and transmit copies (print or electronic) for institutional and academic purposes.
3. The IIUM library will have the right to make, store in a retrieved system and supply copies of this unpublished research if requested by other universities and research libraries.
By signing this form, I acknowledged that I have read and understand the IIUM Intellectual Property Right and Commercialization policy.
Affirmed by Siti Munirah Salimah binti Abd Rashid
In the Name of Allah, the Most Gracious, the Most Merciful
Firstly, gratitude and appreciation are for Allah, the Most Merciful and Most Compassionate for granting me a precious opportunity to complete this research work and granted me health and strength.
I would like to convey my deepest appreciation to my respected supervisor Assoc. Prof. Dr. Hazleen Anuar for her encouragement, support and invaluable guidance towards a successful realization of the research and the write up of this thesis. I also would like to thank to my co-supervisors, Dr. Yose Fachmi Buys, Dr.
Noor Azlina Hassan and En. Romainor for their support.
It is my utmost pleasure to dedicate this work to my dear parents and my family, who granted me the gift of their unwavering belief in my ability to accomplish this goal: thank you for your support and patience.
Lastly, I would like to thank to my colleagues and friends for their continuous help and support and also Br. Hairi and Br. Syamsul for their assistance in successfully completing this research.
TABLE OF CONTENTS
Abstract ... ii
Abstract in Arabic ... iii
Approval Page ... iv
Declaration ... v
Acknowldgements ... vii
Table of Contents ... viii
List of Tables ... xi
List of Figures ... xii
List of Abbreviations ... xiv
List of Symbols……….xv
CHAPTER ONE: INTRODUCTION ... 1
1.1 Background ... 1
1.2 Problem Statement ... 3
1.3 Objectives ... 5
1.4 Scope of Research... 5
1.5 Thesis Organization ... 6
1.6 Summary ... 7
CHAPTER TWO: LITERATURE REVIEW ... 8
2.1 Introduction... 8
2.2 Biopolymers ... 8
2.2.1 Polylactic Acid ... 10
126.96.36.199 Biodegradation of PLA ... 13
2.3 Natural Fibre ... 14
2.3.1 Surface Treatment of Natural Fibre ... 17
2.3.2 Mercerization Process (Alkali Treatment) ... 17
2.3.3 Durian Skin Fibre (DSF) ... 18
2.4 Plasticizers ... 20
2.4.1 Natural-based Plasticizer ... 21
2.4.2 Epoxidized Palm Oil (EPO) ... 22
2.5 Food Packaging Container ... 23
2.5.1 Food Packaging Materials ... 24
2.5.2 Biodegradable Food Packaging ... 26
2.5.3 Physical Properties of Food Packaging ... 27
2.5.4 Environmental Impact on Food Packaging ... 28
2.5.5 Global Warming ... 29
2.5.6 Acidification... 29
2.5.7 Eutrophication ... 30
2.5.8 Ozone Layer Depletion ... 31
2.6 Measuring Environmental Impacts: Life Cycle Assessment (LCA) ... 33
2.6.1 LCA Framework ... 35
2.7 Summary ... 37
CHAPTER THREE: METHODOLOGY ... 40
3.1 Introduction... 40
3.2 Materials ... 41
3.2.1 Polylactic Acid (PLA) ... 41
3.2.2 Durian Skin Fibre (DSF) ... 41
3.2.3 Epoxidized Palm Oil (EPO) ... 41
3.3 Preparation of Treated DSF ... 43
3.3.1 Preparation of DSF... 43
3.3.2 Mercerization Process of DSF ... 43
3.4 Preparation of Biocomposite ... 44
3.5 Chemical Properties Characterization ... 45
3.5.1 Fourier Transform Infrared (FTIR) Analysis ... 45
3.6 Mechanical Properties Characterization ... 45
3.6.1 Tensile Test ... 45
3.6.2 Flexural Test ... 46
3.6.3 Impact Test ... 46
3.7 Morphological Observation ... 46
3.8 Thermal Properties Characterization ... 47
3.8.1 Thermogravimetric Analysis (TGA) ... 47
3.8.2 Differential Scanning Calorimetry (DSC) ... 47
3.8.3 Dynamic Mechanical Analysis (DMA) ... 47
3.8.4 Vicat Softening Temperature (VST) ... 48
3.9 Physical Properties Characterization ... 48
3.9.1 Water Absorption and Dimensional Stability ... 48
3.9.2 Optical Analysis ... 49
3.10 Fabrication of Food Container ... 50
3.10.1 Biodegradation Property (Soil Burial Test) ... 50
3.11 Life Cycle Assessment (LCA) of PLA/DSF Biocomposite Food Container ... 50
3.11.1 Goal and Scope ... 51
188.8.131.52 Functional Unit ... 52
184.108.40.206 Data Sources and Limitation ... 52
3.11.2 Inventory Analysis ... 53
220.127.116.11 Transportation ... 53
18.104.22.168 Electricity... 54
22.214.171.124 End of life stage ... 54
3.11.3 Impact Assessment ... 56
3.12 Summary ... 57
CHAPTER FOUR: DISCUSSION ... 58
4.1 Introduction... 58
4.2 Chemical Properties ... 58
4.2.1 Fourier Transform Infrared (FTIR) Analysis ... 58
4.3 Mechanical Properties ... 60
4.3.1 Tensile Properties ... 60
126.96.36.199 Tensile Strength ... 60
188.8.131.52 Tensile Modulus ... 62
184.108.40.206 Stress-Strain Curve ... 63
4.3.2 Flexural Properties ... 65
220.127.116.11 Flexural Strength ... 65
18.104.22.168 Flexural Modulus ... 66
4.3.3 Impact Strength ... 67
4.4 Morphological Properties ... 69
4.4.1 Scanning Electron Microscopy (SEM) ... 69
4.5 Thermal Properties... 71
4.5.1 Thermogravimetric Analysis (TGA) ... 71
4.5.2 Differential Scanning Calorimetry (DSC) ... 72
4.5.3 Dynamic Mechanical Analysis (DMA) ... 76
4.5.4 Vicat Softening Temperature (VST) ... 80
4.6 Physical Properties... 82
4.6.1 Water Absorption and Dimensional Stability ... 82
4.6.2 Colour Analysis... 84
4.7 Biodegradability ... 86
4.8 Life Cycle Assessment (LCA) ... 89
4.8.1 Global Warming Potential (GWP) ... 89
4.8.2 Eutrophication Potential (EP) ... 92
4.8.3 Acidification Potential (AP) ... 94
4.8.4 Ozone Layer Depletion Potential (ODP) ... 97
4.9 Summary ... 99
CHAPTER FIVE: CONCLUSION AND RECOMMENDATION ... 100
5.1 Introduction... 100
5.2 Recommendations... 101
REFERENCES ... 103
LIST OF PUBLICATIONS ... 114
Journal(s) ... 114
Journal(s) Proceeding ... 114
AWARDS ... 115
APPENDIX ... 116
LIST OF TABLES
Table 2.1: Difference between synthetic and biodegradable polymer 9
Table 2.2: Tensile properties of PLA composites 12
Table 2.3: Properties of natural fibres and glass fibres 16 Table 2.4: The production of fruits crops, Malaysia, 2017 18 Table 2.5: Comparison of DSF with other natural fibres and synthetic fibre 19
Table 3.1: Composition of biocomposite prepared 45
Table 3.2: Weight for 1 and 50 units for PLA/DSF biocomposites 52 Table 3.3: Weight for 1 and 50 units for PLA/DSF/EPO biocomposites 52
Table 3.4: Electricity usage of each process 54
Table 4.1: Thermal analysis of PLA, PLA/DSF and PLA/DSF/EPO
Table 4.2: DSC properties of PLA, PLA/DSF and PLA/DSF/EPO biocomposites 76 Table 4.3: DMA properties of PLA, PLA/DSF and PLA/DSF/EPO biocomposites 77 Table 4.4: Optical properties of PLA, PLA/DSF and PLA/DSF/EPO
Table 4.5: Contribution of each process to GWP for PLA/DSF and PLA/DSF/EPO
Table 4.6: Contribution of each process to EP for PLA/DSF and PLA/DSF/EPO
Table 4.7: Contribution of each process to AP for PLA/DSF and PLA/DSF/EPO
Table 4.8: Contribution of each process to ODP for PLA/DSF and PLA/DSF/EPO
LIST OF FIGURES
Fig. 2.1: Polymerization of lactic acid 10
Fig. 2.2: Classification of natural fibre 15
Fig. 2.3: Chemical interactions between PLA and EPO 23
Fig. 2.4: Biopolymer usage in various sectors 27
Fig. 2.5: Illustration of human activities on how this is affecting the aquatic life 30 Fig. 2.6: Photolysis process of CFCs and ozone molecule in stratosphere layer 33
Fig. 2.7: Cradle-to-cradle process 34
Fig. 2.8: Scopes of LCA 35
Fig. 2.9: Life cycle assessment frame work 36
Fig. 2.10: Midpoint and endpoint level in LCIA framework 37
Fig. 3.1: Research flowchart 42
Fig. 3.2: Preparation of treated durian skin fibre 44
Fig. 3.3: A simplified life cycle process of PLA/DSF biocomposite food
Fig. 3.4: System boundary for PLA/DSF biocomposite 55
Fig. 3.5: System Boundary for PLA/DSF/EPO biocomposite 56
Fig. 4.1: FTIR spectra of PLA, PLA/DSF and PLA/DSF/EPO biocomposites 59 Fig. 4.2: Tensile strength of PLA, PLA/DSF and PLA/DSF/EPO biocomposites 61 Fig. 4.3: Tensile modulus of PLA, PLA/DSF and PLA/DSF/EPO biocomposites 63 Fig. 4.4: Stress-strain curves of PLA, PLA/DSF and PLA/DSF/EPO
Fig. 4.5: Flexural strength of PLA, PLA/DSF and PLA/DSF/EPO biocomposites 66 Fig. 4.6: Flexural modulus of PLA, PLA/DSF and PLA/DSF/EPO biocomposites 67 Fig. 4.7: Impact strength of PLA, PLA/DSF and PLA/DSF/EPO biocomposites 68
Fig. 4.8: SEM micrographs of (a) PLA, (b) PLA/DSF, (c) PLA/DSF/EPO
Fig. 4.9: TG curves for PLA, PLA/DSF and PLA/DSF/EPO biocomposites 72 Fig. 4.10: DSC curves of PLA, PLA/DSF and PLA/DSF/EPO biocomposites 76 Fig. 4.11: Storage modulus of PLA, PLA/DSF and PLA/DSF/EPO
Fig. 4.12: Loss modulus of PLA, PLA/DSF and PLA/DSF/EPO biocomposites 79 Fig. 4.13: Tan δ of PLA, PLA/DSF and PLA/DSF/EPO biocomposites 80 Fig. 4.14: Softening temperature of PLA, PLA/DSF and PLA/DSF/EPO
Fig. 4.15: Water absorption of PLA, PLA/DSF, PLA/DSF/EPO biocomposites 83 Fig. 4.16: Thickness swelling of PLA, PLA/DSF, PLA/DSF/EPO biocomposites 84 Fig. 4.17: Lightness values of PLA, PLA/DSF and PLA/DSF/EPO biocomposites 85 Fig. 4.18: Biodegradation rate of PLA, PLA/DSF and PLA/DSF/EPO
Fig. 4.19: Physical appearance of PLA, PLA/DSF and PLA/DSF/EPO
Fig. 4.20: The percentage of different types of gas emission for GWP 92 Fig. 4.21: The percentage of different types of gas emission for EP 94 Fig. 4.22: The percentage of different types of gas emission for AP 96 Fig. 4.23: The percentage of different types of gas emission for ODP 98
LIST OF ABBREVIATIONS
AP Acidification potential
BBP Butylbenzyl phthalate
BPA Bisphenol A
CO2 Carbon dioxide
DSC Differential Scanning Calorimetry DDT Dichlorodiphenyltrichloroethane
DMA Dynamic Mechanical Analysis
DEHP di-(2-ethylhexyl) phthalate
DiNP di-isononyl phthalate
DSF Durian skin fibre
EP Eutrophication potential
EPO Epoxidized palm oil
FDA Food and Drug Administration
FTIR Fourier Transform Infrared
GWP Global warming potential
HDPE High-density polyethylene
ISO International Organization for Standardization
KF Kenaf fibre
LCA Life cycle Assessment
LDPE Low-density polyethylene
Mw Moecular weight
MSW Municipal solid waste
MT Metric ton
ODP Ozone Layer Depletion potential
HDPE High-density polyethylene
PAHs Polycyclic aromatic hydrocarbons PBDEs Polybrominated diphenyl ethers
PBS Polybutylene succinate
PEG Polyethylene glycol
PET Polyethylene terephthalate
PHA Polyhydroxyl alkanoate
PLA Polylactic acid
PVC Polyvinyl chloride
SEM Scanning Electron Microscopy
TGA Thermogravimetric Analysis
VST Vicat Softening Temperature
WPO World Packaging Organization
LIST OF SYMBOLS
a* Red-green coordinates
b* Yellow-blue coordinates
L* Lightness and chromaticity coordinates
E Energy (MJ)
Tan δ Ratio of tan delta
Tc Crystallization temperature (°C) Tg Glass transition temperature (°C) Tm Melting temperature (°C)
T1 Initial thickness (mm)
T2 Final thickness (mm)
W1 Initial weight (g)
W2 Final weight (g)
Xc Percentage of crystallinity (%)
∆E Colour difference
ΔHc Enthalpy of crystallization ΔHm Enthalpy of fusion
CHAPTER ONE INTRODUCTION
Food packaging is a container or cover that protects food from contaminations and damage, while maintaining the taste and quality of the food throughout its entire shelf life. Food quality is crucial as the food is consumed by consumers and the affected food quality may give bad effects to human health. According to Shin & Selke (2014), more than 25% of spoiled food was discarded due to poor packaging. Besides, food packaging must be discarded in a proper way after use to prevent environmental problems. In fabricating food packaging, the material selection is one of the prominent factors to its durability and safe to be used. The demand for food packaging materials which satisfies the quality characteristics as specified by the standard food packaging and environmental friendly has increased recently. Most of current food packaging are made of petroleum-based polymer like polystyrene (PS), polypropylene (PP) and polyethylene (PE). Plastics are most commonly used in food packaging industries as it can be formed into a various type of shapes, lightweight, durable and can be processed at relatively low temperatures compared to glass and metal (Shin & Selke, 2014).
According to Othman (2014), biopolymers are polymers that are made up from the covalently bonded monomer forming large structures. Polylactic acid (PLA) is one of the appropriate alternative biopolymers as a packaging material due to its properties and performances that are comparable to synthetic polymers like PP and PE. PLA is one of the most economical biopolymers in the world’s market today. PLA is widely used in food packaging as it can be formed in rigid packaging, films, bottles and cutlery due to the good mechanical properties, thermally stable, biocompatible and
low environment impact as it is fully biodegradable (Penjumras et al., 2015a). PLA is safe to be used as it has been approved by the Food and Drug Administration (FDA) for food contact materials (Ahmed & Varshney, 2011). In Europe and North America, PLA is used for packaging bottled water, juices and yogurts in supermarket products.
However, PLA does have its disadvantages. It is highly brittle, has low durability and has low elongation at break. These drawbacks limit its applications in certain ways. In order to overcome these problems, plasticizer is added into PLA to enhance the flexibility and processability of PLA. Recently, the attention on natural- based plasticizer has grown greatly in the industry as it has low toxicity, sustainable resources, low cost and biodegradable (Czub & Franex, 2013). Moreover, it is widely used as an additive in polymer industry due to high index viscosity, good lubricity and solvency and low vitality (Kamarudin et al., 2018). For example, epoxidized palm oil (EPO) is a favorable natural plasticizer that has been used by many researchers and Malaysia has become one of the major producers of palm oil in the world.
Natural fibre such as kenaf, jute, flax and bamboo are commonly used as a reinforcing agent to produce biocomposite materials. Natural fibre is not only harvested from plant but also agricultural waste like peel, husk and hull. Durian skin is a waste that can be transformed to reinforcement fibre. Penjumras et al. (2015b) state that the total world harvest of durian is 1.4 metric ton (Mt): Thailand is the largest producer with 781 kt, followed by Malaysia and Indonesia with 376 kt and 265 kt, respectively. Generally, about 40% of durian skin fibre could be generated from 1 kg of durian skin waste (Manshor et al., 2014). This waste can be used as a reinforcing agent in biopolymer matrix to enhance its performance by reducing the density as well as lowering the cost of the biopolymer. The DSF contains 68% cellulose, 16%
hemicellulose and 13% lignin with density of 1.243 g/cm3. The reinforcement of DSF
in low linear density polyethylene (LLDPE) was studied by Wan Nazri et al. (2014).
They found that 30% of DSF showed the optimum impact and flexural strength. The Young’s modulus and impact strength of DSF reinforced PLA also increased with increasing of cellulose content at 35% (Penjumras et al., 2015a).
1.2 PROBLEM STATEMENT
Designing and fabricating the food packaging are vital in determining the shelf life of a food product. The right selection of packaging materials mainly food container could maintain the product quality during consumption period by the consumer. The common materials used for food packaging are polystyrene (PS), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP) and polyethylene terephthalate (PET).
However, these plastics are petroleum-based polymers and they are non- renewable resources. They are neither fully biodegradable nor environmental friendly and unaffected from microbial attack. They take very long time to decompose and the continous usage of these plastics lead to a serious problem with long life of plastic waste. It is a global challenge as it takes millions of years for fossil fuels to be replenished (Kuruppalil, 2011). Therefore, the volume of plastic waste increases year by year either on the landfill or in the ocean.
In addition, some states government in Malaysia have banned the use of polystyrene food packaging container as it may hazards human health. It has been proven that the polystyrene has long term effects on all living things. Styrene and benzene are toxic substances contained in polystyrene which may leach out when in contact with hot food or beverages and other types of food that is acidic and contain oil and alcohol (Ahmad & Bajahlan, 2007).
In order to reduce the environmental problems, a ‘green’ material of food packaging should be developed to avoid further destruction of the environment.
Commodity of synthetic polymer can be replaced with non-petroleum resources which is a biopolymer due to its biodegradable nature such as PLA.
Nevertheless, PLA has major drawbacks too. It is known to have brittleness (Ali et al., 2016) and low impact resistance as well as less flexibility (Xing &
Matuana, 2016; Al-Mulla et al., 2014; Silverajah et al., 2012a). To reduce this problem, plasticizer is currently being employed in a biodegradable polymer. Natural- based plasticizer such as epoxidized vegetable oil (EVO) is a natural resource is added in polymer as a replacement for traditionally used phthalates in the plastic industry, which are characterized by their high toxicity (Kamarudin et al., 2018).
The advantages of epoxidized vegetable oil in polymer industry are biodegradable, environmentally friendly, renewable and low cost. Furthermore, it has potential to be used as an additive for polymer industry that requires properties, such as good lubricity, low vitality, high index viscosity and good solvency. Thus, in order to reduce the brittleness and enhance the flexibility and durability of PLA, EPO is used as a plasticizer into PLA/DSF biocomposite as it is obtained from renewable resources, easily available, biodegradable and environmentally friendly.
Therefore, this research worked on the development of fully ‘green’
biodegradable food packaging container from durian skin fibre (DSF) reinforced polylactic acid (PLA) and epoxidized palm oil (EPO) as a plasticizer. The DSF was obtained from biomass, then incorporated into PLA to produce biocomposite as it maintains the truly green characteristics and reduces the cost of PLA. This research also investigated the properties of neat PLA, PLA/DSF and PLA/DSF/EPO biocomposites and the impact of the PLA/DSF biocomposite process on the
environment of this food packaging container from raw materials to the disposal method.
The focal point of this research is to develop biodegradable a food container made from polylactic acid reinforced with durian skin fibre biocomposite. In order to achieve the aim, several objectives are set as follows:
i. To investigate the effect of epoxidized palm oil (EPO) on chemical, mechanical, morphological, thermal and physical properties of PLA/DSF biocomposite.
ii. To fabricate food container and characterize the biodegradation properties of PLA, PLA/DSF and PLA/DSF/EPO biocomposite.
iii. To assess the lifecycle of durian skin fibre (DSF) biocomposite food container.
1.4 SCOPE OF RESEARCH
This research is carried out to produce a biodegradable food container that causes less harm to the environment compared to the current disposable food containers. The biocomposites consisting of PLA/DSF and PLA/DSF/EPO are fabricated via extrusion and injection moulding processes before being characterized according to standard.
Chemical, mechanical, morphological, thermal and physical properties are done to analyse the effects of EPO on PLA. Soil burial test is carried out to determine the biodegradation properties of PLA/DSF biocomposite. Finally, life cycle assessment for PLA/DSF biocomposites with and without EPO is investigated to study the effect of durian skin fibre preparation, manufacturing process of biocomposite on the environment and disposal method which is landfill. The environmental impacts
covered are global warming potential, acidification potential, eutrophication potential and ozone layer depletion potential.
1.5 THESIS ORGANIZATION
This thesis consists of five chapters and the first chapter is an introduction of the research, then literature review, followed by methodology, results and discussion, respectively. The introduction part explains in detail the background and overview of this research, problem statement, objectives and the scope of the research.
Chapter 2 provides review of literatures related to PLA biopolmer, natural fibre, plasticizers, food packaging and life cycle assessment overview and previous works related to the investigation.
The next part is Chapter 3 where it states the procedure from the early steps in producing durian skin fibre, treatment of DSF and fabrication of biocomposite.
Moreover, this chapter shares on the characterization on chemical, mechanical, morphological, thermal and physical of PLA, PLA/DSF and PLA/DSF/EPO related to the process. Next, there is a presentation of analysis of PLA/DSF biocomposite that is used to manufacture food container and its biodegradation properties. Lastly, using GaBi software, the life cycle assesment on PLA/DSF biocomposite to discover the effect of manufacturing process and disposal method on the environment is share as well.
Chapter 4 presents the findings of the biocomposites for all analysis. The first part of Chapter 4 discusses the chemical, mechanical, morphological, thermal and physical properties of unreinforced PLA, reinforced PLA with DSF and plasticized PLA/DSF. Then, biodegradation properties are discussed for all samples. Lastly, the
impact of production for both PLA/DSF biocomposites on environment is shared in this chapter.
The last part is the conclusion that summarizes or determines to which extent the research objectives have been achieved. It also discusses the advantages and limitations of this research and recommendations to improve this research.
This chapter has presented and discussed the background of the study. It explained the effect of current food packaging container by using petroleum-based polymer. The problem statement was discovered and this research was conducted to find an alternative to substitute the petroleum-based polymer. This chapter also discussed the sub-objectives of this research in order to complete the main objectives. Finally, the details of the research scope was elaborated from the first process until the end followed by organization of this thesis.
CHAPTER TWO LITERATURE REVIEW
Over the past few decades, the most polymers used are petroleum-based which are non-renewable and non-biodegradable. These polymers give serious problems to the environment as they take a very long time to decompose. As a result, the quantity of commercial and industrial dumps in the landfills were increased (Penjumras et al., 2015a). In order to reduce related waste to environment and reduce dependency on the fossil fuels, biopolymers are the most suitable substance to replace the petroleum- based polymers. This is due to their biodegradable nature and as renewable and sustainable resources. However, biopolymer has low durability, slow biodegradation rate and rather costly and these have become a limitation on its applications. So, incorporation of natural fibre as a filler and plasticizer as an additive in the composite may overcome these drawbacks.
Biodegradable polymer or biopolymer has gained massive attention recently especially in the production of food container, general packaging, biomedical application, drug delivery system and pharmaceutical technologies. Bratovcic et al.
(2015) stated that the global production of biopolymer in 2013 was 1.6 million tons and it increased by 28% with 2.05 million tons in 2017. In fact, Asia was the highest producer of PLA with 56%. The major advantage of biopolymer is it can preserve the fossil fuel resources and reduce the environmental problem. So, it could be an effective alternative to substitute petroleum-based polymer in producing the desired
product. Biopolymer has the tendency to degrade after disposal. However, it can be resistant to degrade during utilization period as it does not expose to the open environment (Velde & Kiekens, 2002) and its degradation depends on some parameters like environmental factors and presence of microorganisms. The use of biomass as raw materials should be considered due to the limitation of natural gas resources and crude oil in the long term as they take years to replenish. The comparison between synthetic and biodegradable polymer are summarized in Table 2.1.
Table 2.1: Difference between synthetic and biodegradable polymer (Makhijani et al., 2015)
Synthetic polymer Biopolymer - Synthesized using fossil fuels as
- Synthesized using natural resources
- Resources are diminished - Resources are abundant in nature - Can be processed easily into various
- Shapes cannot be easily obtained as their native structure is destroyed during processing at high temperature - Contain compounds that do not allow
- Cannot be degraded by microbial action
- Physical recycling is impractical and undesirable
- Physical recycling is beneficial as it leads to soil enrichment
- Relatively cheap and easily available - Processing from natural resources is a costly, hence they are expensive and very few are currently available