Post on 21-Mar-2020
CHARACTERIZATION AND BIODEGRADABILITY OF EXTRUDED
FOAMED POLYPROPYLENE FILLED PINEAPPLE LEAF FIBER
BIOCOMPOSITES
RAFIDAH BINTI RUSMAN
A project report submitted in partial fulfilment of
the requirements for the award of the degree of
Master of Science (Polymer Technology)
Faculty of Chemical Engineering
University Teknologi Malaysia
NOV 2010
iii
Specially dedicated to my beloved parents,
family and friends
Thanks for encouraging and supporting me.
iv
ACKNOWLEDGEMENT
“In the name of Allah SWT, the most gracious and most merciful”
I would like to take this opportunity to express my deepest appreciation to my
respectful supervisors, Assoc. Prof. Dr. Wan Aizan Wan Abdul Rahman and Dr.
Zurina Mohammad for their supports, supervision and guidance towards the
completion of this research.
Special thanks also go to all staffs from the Department of Polymer Engineering
supported me in my research work. I want to thank them for all their assistances,
support, interest and inspiration. Most importantly to Ms. Zainab Salleh, Mr.
Suhee Tan Hassan and Mr. Azri.
My sincere appreciation also extends to all the lecturers who have taught valuable
knowledge throughout the learning semester in UTM. Not forgetting, my course
mates and all postgraduate students for all their ideas and motivation.
Finally, I am also indebted to my beloved parents and also all the persons who
involved directly and indirectly in the success of this research. Above all, I thank
Allah the Almighty for His grace, mercy and guidance throughout my life. Thank
You.
v
ABSTRACT
Polymer foam biocomposites based on Polypropylene (PP)-Pineapple Leaf
Fiber (PALF) were successfully produced by an extrusion foaming
process. The compounding of PP with PALF was performed in twin-screw
extruder which blend the materials with dicumyl peroxide (DCP) and
chemical blowing agent (ADC). The DCP (1%) and ADC (1.5%) were
kept constant while PALF content were varied from 0% to 30% by weight.
After forming the foam, samples was prepared for water absorption test
(ASTM D-2842), density determination and biodegradability test (ASTM
G21). The PP-PALF biocomposite foam was characterized using
Thermogravimetry Analysis (TGA) and Differential Scanning Calorimetry
(DSC). It was found that PP-PALF biocomposite foam is open-cell foam
and is proved by the water absorption test which increased linearly with
increment of PALF loadings. From the DSC result, it was showed that the
percent of crystallinity decreases with increased in filler loading and the
melting temperature of the PALF-PP biocomposite foam were not much
affected by incorporation of PALF. Finally, the additions of pineapple leaf
fiber into each formulation have significantly improved the
biodegradability of the biocomposites.
vi
ABSTRAK
Biokomposit polimer berbusa berasaskan gentian daun nenas (PALF) diisi
polypropiline (PP) telah Berjaya dihasilkan melalui proses penyemperitan. Proses
penyaemperitan PP dan PALF telah dilakukan dengan menggunakan mesin
penyemperitan screw berkembar. Bahan mentah ini kemudiannya diadunkan pula
bersama-sama dicumyl perosida (DCP) dan agen pembuih kimia (ADC) untuk
menghasilkan biokomposit berbusa. Dalam kajian ini, hanya kandungan PALF
dipelbagaikan dari 0% hingga 30% daripada berat keseluruhan, manakala
kandungan DCP (1%) dan ADC (1.5%) adalah tetap. Selepas proses
penyemperitan berbusa, sampel-sampel ini kemudiannya telah menjalani proses
penentuan ketumpatan, ujian penyerapan air (ASTM D-2842) dan ujian
kebolehuraian (ASTM G21). Proses pencirian juga telah dilakukan ke atas
biokomposit berbusa tersebut. Mikrogaf optikal (SEM) pula telah digunakan
untuk mengkaji struktur sel biokomposit bebusa tersebut. Pemerhatian
menggunakan SEM telah mendedahkan bahawa struktur sel biokomposit berbusa
ini terdiri daripada sel-sel terbuka. Dari proses penentuan ketumpatan pula telah
menunjukan berlakunya peningkatan ketumpatan bagi setiap komposit berbusa
apabila kandungan PALF ditambah. Peningkatan kandungan PALF juga
mengurangkan peratusan hablur yang hadir dalam setiap biokomposit berbusa
tersebut. Akhir sekali, penambahan PALF juga telah meningkatkan kadar
kebolehuraian bagi setiap biokomposit berbusa tersebut.
vii
TABLE OF CONTENTS
CHAPTER
TITLE PAGES
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENT vii
LIST OF TABLES x
LIST OF FIGURES xi
LIST OF ABBREVIATIONS xiv
LIST OF APPENDICES xv
1
INTRODUCTION
1.1 Research Background 1
1.2 Problem Statement 4
1.3 Objectives of Study 5
1.4 Scope of Research 5
1.5 Significance of Study 6
2
LITERATURE REVIEW
2.1 Introduction 8
2.2 Polymer Biocomposite 9
2.3 Natural Fiber 12
2.3.1 Pineapple Leaf Fiber (PALF) 14
2.4 Polymeric Foams 15
2.4.1 The Formation of Foam Structure in Polymer 26
2.4.2 Foam Morphology 30
2.4.3 Characteristic of Foaming Agent 31
2.5 Biodegradation of Polypropylene 34
viii
3
RESEARCH METHODOLOGY
3.1 Introduction 39
3.2 Raw Material Preparation
3.2.1 Polypropylene (PP) 39
3.2.2 Preparation of PALF 40
3.2.3 The Foaming Agent 42
3.2.4 Foam Nucleating Agent 42
3.3 Extrusion Foaming 43
3.4 Testing Method 45
3.4.1 Density Determination 46
3.4.2 Scanning Electron Microscope 46
3.4.3 Water Absorption of Rigid Cellular Plastics 48
3.4.4 Determining Resistance of Synthetic Polymeric
Materials to Fungi 51
3.4.5 Differential Scanning Calorimetry 52
3.4.6 Thermogravimetry Analysis 53
4
RESULTS AND DISCUSSION
4.1 Physical Properties 55
4.1.1 Density 55
4.1.2 Morphological Analysis 57
4.2 Thermal Properties
4.2.1 Differential Scanning Calorimetry 59
4.2.2 Thermogravimetry Analysis 61
4.3 Physical Tests
4.3.1 Water Absorption 63
4.3.2 Biodegradability 65
ix
5
CONCLIUSIONS AND RECOMMENDATIONS
5.1 Conclusion 68
5.2 Recommendation 70
REFERENCES 71
APPENDICES 78
x
LIST OF TABLES
TABLE
NO. TITTLE PAGE
2.1 Advantage and Disadvantage of Composite 10
2.2 Physical and Mechanical Properties of PALF 15
2.3 Foam Properties and Application Attributes 17
2.4 Various Literature Reports on Biodegradation Polypropylene 38
3.1 Properties of Polypropylene (TITANPRO6331) 40
Typical Physical Properties of Cellcom AC-1000C Chemical
3.2 Raw Materials Formulation and Composition 44
3.3 Reagents for Nutrients Salts Agar 52
4.1
Density of pure PP foam and PP/PALF foam composites for
various PALF content 55
4.2 The thermal parameter DSC of PP/PALF foam composite 59
4.3 TGA data for pure PP and PP/PALF foam biocomposites 62
4.4
Percentage of Water Absorption of pure PP foam and
PP/PALF foam composite
63
xi
LIST OF FIGURES
FIGURE
NO. TITTLE PAGE
2.1 Categories of Natural Fiber 14
2.2 Effect of Silane Treated Rossells and the Addition of
Compatibilizer on Tensile and Impact Strength
18
2.3 Relationship between compressive strength and density of PP
foam.
20
2.4 Effects of blowing time and cross-linking agent (VTMOS) on
the density of PP foam at 0.5 phr ADCA. (BPO: 0.5 phr;
CAT: 0.15 phr).
21
2.5 Effects of blowing time and cross-linking agent (VTMOS) on
the density of PP foam at 1.0 phr ADCA. (BPO: 0.5 phr;
CAT 0.15 phr).
21
2.6 Effect of cross-linking agent (VTMOS) on the expansion
ratio of PP foam. (BPO: 0.5 phr; CAT: 0.3 phr, blowing time:
30 min).
22
2.7 Effect of cross-linking agent (VTMOS) on the gel fraction of
PP foam. (BPO: 0.5 phr.)
23
2.8 Effect of cross-linking accelerator (CAT) on the gel fraction
of PP foam. (BPO: 0.5 phr)
24
2.9 Effect of cross-linking initiator (BPO) on the gel fraction of
PP foam. (VTMOS: 2 phr; CAT: 0.3 phr).
25
2.10 Surface morphology of composites: (a) unmodified,
(b) OTMS_3hr,
xii
(c) MAPP_1phr, (d) MAPP_2phr, (e) MAPP_4phr, (f)
MAPP_6phr, (g) MAPP_8phr and (h) MAPP_10phr.
26
2.11 The Principle of Batch Foaming 27
2.12 The Principle of Continous Foaming 28
2.13 Morphological Changes in the Extrudate During
Microcellular Processing
29
2.14 Comparative lengths for morphological features in a foam 31
2.15 Typical isothermal gas evolution curves for
azodicarbonamide at various temperatures.
33
2.16 Overview of degradation of polymers (Adapted from Vasile) 35
3.1 Two Roll Mill Machine Used For Remove Water 41
3.2 Long PALF Extracted From Raw Leaf 41
3.3 Chopped PALF 41
3.4 Schematic of an extrusion foaming process 45
3.5 Sample placed on the stub before coated 47
3.6 Sample placed on the stub after coated with platinum 48
3.7 Empty submerged jig 49
3.8 Submerged jig with test specimens
50
4.1 Density determination of foam samples at different filler
loading
56
4.2 Effect of PALF content on cell morphology at (a) 0 wt%, (b)
10 wt%, (c) 20 wt%, and (d) 30 wt%
58
xiii
4.3 TGA curves of PP/PALF foam for various PALF contents 61
4.4 Percentage of water absorption of pure PP foam and
PP/PALF foam composite with different filler loading
64
4.5 Photograph of microbial growth on the film surface of PP/PALF 66
foam composites at (a) 0 wt%, (b) 10 wt%, (c) 20 wt%, and
(d) 30 wt%
xiv
LIST OF ABBREVIATIONS
PP
Polypropylene
PALF
Pineapple Leaf Fiber
DCP
Dicumyl Peroxide
ADC
Azodicabonamide
ASTM
American Society for Testing and Materials
TGA
Thermogravimetry Analysis
DSC
Diffential Scanning Calorimetry
SEM
Scanning Electron Microscope
SHSD
Sunflower Hull Sanding Dust
SITRA
South India Textile Research Association
MAPP
Maleic Anhydride Polypropylene
OTMS
Octadecyltrimethoxysilane
ADCA
Azodicarbonate
BPO
Benzyl Peroxide
CAT
di-nbutyltin dilaurate
VTOMS
Vinyl Trimethoxy Silane
CFA
Chemical Blowing Agent
PFA
Physical Blowing Agent
VOC
Volatile Organic Content
HC
Hydrocarbon
CFC
Chlorofluorocarbon
HFC
hydrofluorocarbon
HDPE
High Density Polethylene
LLDPE
Low Linear Density Polyethylene
LDPE
Low Density Polyethylene
EM
Effective Microorganism
∆Hf
Heat of Fusion
Tm
Melting Temperature
Xcom
Percent Crystallinity
Xpp
Crystallinity of PP in the Composite
∆H
Heat of Fusion of Perfectly Crystalline
xv
LIST OF APPENDICES
APPENDIX TITLE PAGE
A Cell Morphology of Pure PP Foam 78
B Cell Morphology of PP/PALF (10% PALF) Biocomposite
Foam 78
C Cell Morphology of PP/PALF (20% PALF) Biocomposite
Foam 79
D Cell Morphology of PP/PALF (30% PALF) Biocomposite
Foam 79
E Raw Data for Water Absorption Determination 80
F TGA Thermogram for PP/PALF (10% PALF) 81
G TGA Thermogram for PP/PALF (20% PALF) 82
H TGA Thermogram for PP/PALF (30% PALF) 83
I DSC Thermogram for PP/PALF (10% PALF) 84
J DSC Thermogram for PP/PALF (20% PALF) 84
K DSC Thermogram for PP/PALF (30% PALF) 85
CHAPTER 1
INTRODUCTION
1.1 Research Background
The use of polymeric foam in today‟s world has constantly increased. Many
reasons support this growth: light weight, insulation properties, softness, excellent
strength/weight ratio, material costs and energy absorption performance. Many times
reductions after foaming in material costs are around 30% without compromising the
function or required strength, which is one of the advantages that could lead to even
wider use of foams in industry. The chemicals used are today environmental friendly
and the mechanical and barrier properties can be greatly affected by multilayer
constructions; mechanically strong sandwich structures can be produced with solid skin
layers, low gas permeability polymers and tie layers support their use for high barrier
packages (Krayink et al., 1987).
The main applications for foamed plastics can be found in the building,
automobile, packaging and sport industries. They include the end products for insulative
2
sheets, floor coverings, and profile for finishing, automobile linings, packaging films,
cable wires, interior finishing, shoes and cups (Kumar, 1993).
Because of environmental demands, foamed polymers have also been threatened
and raw material and process manufactures have been forced to find solutions for
recyclable polymers and alternatives for blowing agents‟ deleterious effects on the ozone
layer. These challenges have led studies more away from the traditional materials,
polystyrene and polyurethane and towards the use of polyolefins, polyethylene and
polypropylene (Fox and Goodman, 1993). The tremendous growth in the use of foams in
the last three decades has also created a serious problem of waste disposal and to
overcome this problem, natural fiber will be added to make the foam biodegradable
(Daniel Klempner and Vahid Sendijarevic, 2004).
In Malaysia, agriculture is an important sector of economy. Traditionally,
agricultural materials have been shipped away for processing, or disposed of
postharvest. Diversification of the industry is crucial in encouraging economic stability
and growth. Value-added processing would helps in agricultural diversification.
Pineapple Leaf Fiber (PALF), the subject of the present study, is a waste product of
pineapple cultivation. Hence, pineapple fiber can be obtained for industrial purposes
without any additional cost.
Traditional plastic materials are reinforced by the non-biodegradable fiber, which
are both expensive and harmful to the environment. A fiber based biocomposite material
contains polymers reinforced with natural fiber. There are number of advantages of
using natural fibers in biocomposites, among which are: a) natural fiber will make the
material partially biodegradable; b) natural fiber, in this research is PALF is currently
disposed of by burning; and c) PALF is a low cost, low density and low energy
consumption. Over the past decade, cellulosic fillers have been of greater interest as they
3
improve composites mechanical properties compared to those containing non-fibrous
fillers. In recent years, thermoplastic materials have been increasingly used for various
applications (Folkes, 1982).
Research on a cost effectiveness modification of natural fiber is necessary since
the main attraction for today‟s markets of biocomposites is the competitive cost of
natural fiber. This research attempts to address the following question: do PALF have
any influence on the foam properties. Polymer reinforced biocomposites have
demonstrated a marked improvement in the physical properties of polymeric materials.
Natural fibers have proven to yield many desirable properties when utilized as
reinforcing agents in polymer composite (Sui et al., 2009).
Since the tensile strength for these natural fibers are low, the composites reach
only of about 60 % of the tensile strength of the GF-PP composites. However the
Young‟s moduli are commonly higher than those of GF-PP composites. By considering
the economy factors where the natural fiber are abundant and are relatively cheap
compare to engineering glass fiber, natural fibers have their significant important in the
composite field as reinforcement.
Although there are not many tests carried out for the flexural properties of
composites, this property is important to study the fracture behavior. Regarding PALF
reinforced polyester, Uma Devi et al. (1997) pointed that the addition of fiber made the
composite more ductile. In her work, the flexural strength values of the PALF-polyester
composites were less than the pure polyester at low weight fractions (10 wt %) of the
fiber. Further increased of the fiber loading, the flexural strength had improved by
nearly 120 % for composite containing 30mm long fibers. But when reach more than 30
wt %, the flexural modulus decreased. At 40 wt %, the flexural strength decreased cited
13 % of value. To explain this, the author pointed that higher fiber loading encouraged
4
fiber-to-fiber interaction and the fiber were not well dispersed within the resin latex. For
this research, the best result was obtained at fiber loading of 30 wt %.
In order to take full advantage of the natural agriculture processing by-product,
this study will comminute and compound PALF in Polypropylene (PP) matrix, which
will then be foamed to enhance light weight properties of the finished polymer foam
biocomposites. Generally, this research is conducted to develop PP/PALF foam
biocomposites to attain the desired properties for the application in construction
(pellets), packaging (example: egg tray, fruits tray) and furniture industry (synthetic
wood).
1.2 Problem Statement
The use of plastic foam creates lots of difficulties and problem such as high cost
and environmental pollution. Moreover polymer foams difficult to dispose. Thus, the
best solution to overcome these problems is to produce partially biodegradable materials
such as polymer foam biocomposite. Creating a cellular structure to produce foam
thermoplastics and utilizing inexpensive fillers to manufacture thermoplastic composites
are two effective ways of addressing the price challenge and improve biodegradability.
The large consumption of thermoplastics continues to draw deep development
effort to improve resin manufacturing, which becomes phenomenal support to the foam
industry. It is well-known that thermoplastic foams have lot advantages compared to
thermoplastic itself. However, the research and development in thermoplastic foam
5
biocomposite is less conducted. Thus, this study emphasis on the extrusion foaming
process for PP/PALF foam biocomposite. This project is mainly to evaluate:
i. Is PALF enhance the physical, thermal and morphological properties and
reduce weight of the biocomposite?
ii. What is the effect of PALF loading on the biocomposite foam?
iii. Does addition of PALF improved the biodegradability of the
biocomposites?
1.3 Objectives of Study
The objectives of this research are to:
i. To study the cell morphology and cell size of the composite by Scanning
Electron Microscopy (SEM).
ii. To investigate the effect of filler loading on physical and thermal
properties of PP/PALF foam biocomposites.
iii. To investigate the effect of filler loading on the biodegradability.
1.4 Scopes of Research
The scopes of research are:
i. Preparation of short pineapple leaf fiber (PALF)
6
ii. Extrusion Foaming
iii. Testing to study properties:
- Density
- Water Absorption of Rigid Cellular Plastics (ASTM D2842)
- Resistance of Synthetic Polymer Material to Fungi
(ASTM G21)
v. Scanning Electron Microscope (SEM) to study the cell morphology and
cell size
iv. Differential Scanning Calorimetry (DSC)
v. Thermogravimetry Analysis (TGA)
This study focuses on the effect of foaming process condition and the properties
of PP/PALF foam biocomposite. Foam biocomposites are prepared by using extrusion
foaming technique. Materials used are Polypropylene (PP), pineapple leaf fiber (PALF),
azodicarbonamide (ADC) and dicumyl peroxide (DCP). The filler loading varies in
order to study the effects on foam properties. The foam biocomposite cell structures are
characterized by using Scanning Electron Microscope (SEM).
1.5 Significance of Study
Biocomposite based on polypropylene (PP) and natural filler (pineapple leave
fiber) use as synthetic wood that can replace the wood in the furniture industries and
packaging such as egg and fruit tray in Malaysia. Due the abundance of natural filler
(rice husk, rice straw, kenaf, etc.) in Malaysia, biocomposite simply provides the
alternative for wood apart from several other benefits such as biodegradability, low
density, renewable resources, non-abrasive and low cost due to low material usage. In
7
addition, foaming is introduced to enhance the light weight of material to suit certain
industrial needs. The establishment of structure and properties relationship will help
manufacturer to predetermine the biocomposite material properties based on the
component composition and processing parameter since this relates to the structural and
morphological behavior. In brief, this study is important for development of
thermoplastics filled foam biocomposite as it will provide lots of advantages in the
related industries.
72
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