empty fruit bunch fiber composite -...
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UNIVERSITI TEKNIKAL MALAYSIA MELAKA
EMPTY FRUIT BUNCH FIBER COMPOSITE
This report submitted in accordance with requirement of the Universiti Teknikal
Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Engineering Materials) with Honours.
by
NORJULIA SURIATI BINTI GHAZALY
FACULTY OF MANUFACTURING ENGINEERING
2009/2010
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA
TAJUK: EMPTYFRUIT BUNCH FIBER COMPOSITE
SESI PENGAJIAN: 2009/10 Semester 2
Saya NORJULIA SURIATI BINTI GHAZALY mengaku membenarkan Laporan PSM ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:
1. Laporan PSM adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis. 2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja dengan izin penulis. 3. Perpustakaan dibenarkan membuat salinan laporan PSM ini sebagai bahan
pertukaran antara institusi pengajian tinggi.
4. **Sila tandakan (√)
SULIT
TERHAD
TIDAK TERHAD
(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia yang termaktub di dalam
AKTA RAHSIA RASMI 1972)
(Mengandungi maklumat TERHAD yang telah ditentukan
oleh organisasi/badan di mana penyelidikan dijalankan)
Alamat Tetap:
1203 Jalan Pasir Panjang
21100 Kuala Terengganu
Terengganu Darul Iman
Tarikh: 20 April 2010
Disahkan oleh:
Cop Rasmi: Tarikh: 20 April 2010
** Jika Laporan PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh laporan PSM ini perlu dikelaskan sebagai
SULIT atau TERHAD.
DECLARATION
I hereby, declared this report entitled “Empty Fruit Bunch Fiber Composite” is the
results of my own research except as cited in references.
Signature : …………………………………………
Author‟s Name : Norjulia Suriati binti Ghazaly
Date : 20 April 2010
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of UTeM
as a partial fulfillment of the requirements for the degree of Bachelor of
Manufacturing Engineering (Engineering Materials) with Honours. The member
of the supervisory committee is as follow:
………………………………
(Principal Supervisor)
(Mr Yuhazri bin Yaakob)
ABSTRACT
The purpose of this research was to study and test a composite material for use in
manufacturing product. The manufacturing of the product needs raw material that
meet the specification such as stiff, safe to use, and easy to fabricate. In this research,
thermoplastic that is Polypropylene resin with Maleic Polypropylene (MAPP) as
additives is used to be studied so that a final specimens based on this material can be
fabricated. Before fabricate the composite, the Empty Fruit Bunch Fibers (EFBF) as
reinforcement was treated using alkali solution that is NaOH to removing the
residual oil and contaminant. By using the Hydraulic Hot Press Machine, the plastic
composite is produced in frame with size 25 cm X 25 cm x 0.3 cm and the melting
temperature is 180º C. The effects obtained after the modification have been
analyzed by mechanical and physical testing which are tensile, flexural, shore
durometer hardness, flammability, water and moisture absorption were determined
according to ASTM standards. In this study mechanical and physical properties will
analyze to determine the best composition. It was observed that, the addition of
EFBF content enhanced the physical and mechanical testing. From the test have been
done, the best composition is S/N 1. Although this composition is the matrix, but it
properties is the best in both of testing. For mechanical testing, S/N 1 is good in
flexural strength, tensile strength, young modulus, with the higher value for flexural
strength, tensile strength and young modulus are 30.76 Mpa, 18.46 Mpa and 14.81
Mpa. While for physical testing, S/N 1 best in water absorption and moisture
absorption properties with the values are 0 percent.
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ABSTRAK
Penyelidikan ini membincangkan tentang bahan komposit yang digunakan dalam
bidang pengeluaran produk. Pengeluaran produk memerlukan bahan mentah bagi
mencapai permintaan seperti kekakuan, selamat digunakan dan senang untuk
dihasilkan. Dalam kajian ini, termoplastik iaitu resin Polipropelina dengan MAPP
iaitu sebagai bahan penambah digunakan untuk menghasilkan produk akhir. Sebelum
penghasilan komposit, tandan kosong kelapa sawit sebagai bahan penguat akan
dirawat dengan menggunakan larutan alkali iaitu sodium hidroksida untuk
menanggalkan sisa minyak dan bahan pencemaran. Dengan menggunakan mesin
pemampatan berhidraulik, komposit akan dihasilkan dalam rangka yang bersaiz 25
cm X 25 cm x 0.3 cm dan suhu lebur ialah 180º C. Kesan yang terhasil selepas
pengubahsuaian tersebut dianalisis dengan menggunakan ujian mekanikal dan fizikal
seperti ujian keterikan, kelenturan, kekerasan, kebolehbakaran serta daya serapan air
dan kelembapan yang dijalankan mengikut piawai ASTM. Dalam kajian ini, sifat-
sifat mekanikal dan fizikal di analisis untuk menentukan komposisi yang terbaik.
Daripada pemerhatian, penambahan komposit tandan kosong kelapa sawit ke dalam
PP mampu meningkatkan ujian fizikal dan mekanikalnya. Daripada ujian yang
dibuat, didapati komposisi yang terbaik ialah S/N 1. Walaupun komposisinya ialah
bahan mentah, tetapi ianya mempunyai sifat mekanikal dan fizikal yang terbaik. Bagi
ujian mekanikal, S/N 1 terbaik dalam sifat- sifat keterikan, kelenturan dan „Young
Modulus‟ dengan nilai tertinggi bagi keterikan, kelenturan dan„Young Modulus‟
ialah 30.76 Mpa, 18.46 Mpa dan 14.81 Mpa. Semantara bagi ujian fizikal pula, S/N 1
terbaik dalam ujian serapan air dan kelembapan dengan nilai 0 peratus.
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DEDICATION
Mom and dad
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ACKNOWLEDGEMENT
Alhamdulillah, finally I have finished my Final Year Project for the fulfillment of
Bachelor of Manufacturing (Engineering Material). First and foremost, I would like
to dedicate my deepest gratitude to University Teknikal Malaysia Melaka, especially
for Manufacturing Faculty for the provision of funding to carry out this research and
my bachelor degree study. A special thanks to my supervisor En Yuhazri bin Yaakob
for the supervision along the time I was doing this project. I greatly appreciate his
consistent encouragement, advice and invaluable guidance throughout the course of
this project. I also like to express my thanks to all technician staff at FKP Laboratory
that helping me in gives the information that relate with my study especially about
the machine that have in this lab. Finally I would like to express my deepest
appreciation and gratitude to my family and members for their sacrifice, motivation
and support given during the course of this project.
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TABLE OF CONTENT
NO PAGES
Abstract i
Abstrak ii
Dedication iii
Acknowledgement iv
Table of Content v
List of Tables vii
List of Figures viii
List of Abbreviations ix
1.0 INTRODUCTION
1.1 Background 1
1.2 Problem Statement 3
1.3 Objectives 3
1.4 Scope of Research 4
1.5 Rational of Research 5
1.6 Thesis Frame 5
2.0 LITERATURE REVIEW
2.1 Composite Materials 6
2.1.1 Definition of Composite 6
2.1.1.2 Classifications of Composite Materials 7
2.2 Matrices 8
2.2.1 Thermoset 8
2.2.2 Thermoplastic 9
2.2.2.1 Polypropylene (PP) Composite 10
2.3 Additives 11
2.3.1 Coupling Agents 11
2.3.1.1 Coupling Ratio 15
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2.4 Fiber Reinforcement 16
2.4.1 Stiff and Strong Fiber 16
2.4.2 Lignocellulose Fiber Composite 17
2.4.3 Natural Fiber 18
2.5 Oil Palm Empty Fruit Bunch Fiber (OPEFB) 21
2.5.1 Physical Properties of EFB 23
2.6 Manufacturing Processes 24
2.6.1 Hot Press 24
2.7 Mechanical and Physical Properties 25
2.7.1 Mechanical Properties Testing 25
2.7.1.1 Tensile Test 26
2.7.1.2 Flexural Test 26
2.8 Physical Properties Testing 28
2.8.1 Moisture Content 28
3.0 METHODOLOGY
3.1 Introduction 31
3.2 Material Preparation 33
3.3 Specimens Fabrication 34
3.4 Mechanical Testing 36
3.4.1 Tensile Test 36
3.4.2 Flexural Modulus Test 38
3.4.3 Shore Durometer Hardness Test 39
3.5 Physical Testing 40
3.5.1 Moisture Absorption Testing 40
3.5.2 Water Absorption 42
3.5.3 Flammability 42
4.0 RESULTS AND ANALYSIS
4.1 Introduction 45
4.2 Specimens Analysis 45
4.3 Hardness Analysis 48
4.3.1 Comparison with Previous Study 50
4.4 Flexural Analysis 52
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4.4.1 Flexural Strength Analysis 52
4.4.2 Flexural Modulus Analysis 54
4.4.3 Comparison with Previous Study 55
4.4.4 Flexural Properties 56
4.4.5 Sampling Analysis for Flexural Test 57
4.5 Tensile Analysis 59
4.5.1 Tensile Strength 59
4.5.2 Young Modulus Analysis 61
4.5.3 Comparison with Previous Study 62
4.5.4 Tensile properties. 63
4.5.5 Sampling Analysis for Tensile 64
4.6 Physical Testing Analysis 66
4.6.1 Water Absorption Testing Analysis 66
4.6.1.1Comparison with Previous Study 68
4.6.1.2 Properties of Water Absorption 69
4.6.2 Moisture Absorption Testing Analysis 71
4.6.3 Flammability Testing Analysis 73
4.6.4 Flammability Testing Observation 74 5.0 CONCLUSION
5.1 Conclusion 76
5.2 Recommendations 77
REFERENCES 78
APPENDICES
A Gantt Chart PSM 1 82
B Gantt Chart PSM 2 83
C The Tensile Graph 84
D The Flexural Graph 91
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LIST OF TABLES
NO TITLE PAGES
2.1 Optimum Ratios of Coupling Agent 15
2.2 Ratio of Compounding the Fiber, PP and 6 percent of MAPP 15
2.3 Advantages and Disadvantages of Natural Fiber 21
2.4 World Mature Areas of Oil Palm 22
2.5 Lists the press settings for each material composition 24
2.6 Mechanical properties using E-43 coupling agents (MAPP) 26
2.7 Mechanical properties of natural fiber composites 26
2.8 Mechanical properties of WPC 27
2.9 The Composites due to Moisture Sorption that Investigated 29 2.10 Water absorption and thickness swelling of 30
natural fibers composites
4.1 Composition of Specimens 46
4.2 Hardness Measurement 48
4.3 Flexural Results 52
4.4 Flexural Modulus Results 54
4.5 Tensile Strength data 59
4.6 Young Modulus Result 61
4.7 Water Absorption Testing 67
4.8 Moisture Absorption Testing 72
4.6 The linear burning of PP:EFB:MAPP 74
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LIST OF FIGURES
NO TITLE PAGES
2.1 Resin of Polypropylene that Available at Material Lab 10
2.2 Additives Available at Material Lab 13
2.3 Three Basic Coupling Treatments in WPC 14
2.4 Natural Fiber of Empty Fruit Bunch (EFB)
Available of Felda Tembangau 19
2.5 Natural Fiber Fall into Three Main Categories
Depends of the Origin 19
2.6 Hot Press Machine Available at Composite Lab 24
2.7 Universal Testing Machine 28
3.1 The Flow Chart of Research Methodology 32
3.2 Refined the EFBF 33
3.3 Detech the EFBF 33
3.4 Immersed EFBF with NaOH 33
3.5 Dried the EFBF 33
3.6 Switch on the compress button 35
3.7 Put (PP/EFB/MAPP) onto the plate 35
3.8 Put on at the center position 35
3.9 Samples produce (1 st hot press) 35
3.10 Crushing the samples 35
3.11 Sample Produce (2 nd hot press) 35
3.12 An Example Shape of Tensile Test Bar 36
3.13 Sample Cutter 37
3.14 Test Specimen 37
3.15 Tensile Machine 37
3.16 Loading in the Center of Support Span (3 point band) 38
3.17 Loading in the Center of Support Span (3 point band) 39
3.18 Shore Durometer Hardness 39
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3.19 Oven 41
3.20 Desiccator 41
3.21 Immersion of Specimens 42
3.22 Balance 42
3.23 The Position of Flammability Testing 43
3.24 (a) 25 mm, (b) 75 mm, (c) 20 mm 43
3.25 The Flammability observation 44
3.26 The final specimens after testing 44
4.1 The Defect Mechanisms of EFBF composite, (a) warping, (b) void, 46
(c) bubbles and (d) an unmelted defects.
4.2 Graph of Hardness Value of Differences Ratio 49
4.3 Comparison the Hardness of EFB Composite and Research Results 51
4.4 Graph Flexural Strength of EFBF Composite 53
4.5 The Flexural modulus of PP:EFB 55
4.6 The Flexural Modulus of Natural Fibers 56
4.7 The Fracture not the Middle Side 57
4.8 Not Fracture at the High Loading 58
4.9 Not Fracture at the High Loading 58
4.10 The Tensile Strength of PP:EFB 58
4.11 Graph of Young Modulus relate to Composition 61
4.12 The Comparison of Natural Fiber Composites 62
4.13 The Fracture of Specimens 64
4.14 The Failure of Tensile Testing (bubbles) 65
4.15 Void defects 65
4.16 Graph of Percentage of Water Absorption 67
4.17 The Comparison of Natural Fiber Composites 68
4.18 NaOH as the chemical treatment 70
4.19 Graph of Moisture Absorption 72
4.20 S/N 1 74
4.21 S/N 2 74
4.22 S/N 3 74
4.23 S/N 4 74
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LIST OF ABBREVIATIONS
PP - Polypropylene
POF - Palm Oil Fiber
EFB - Empty Fruit Bunch
MAPP - Maleic Anhydride Polypropylene
NaOH - Sodium Hydroxide
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CHAPTER 1
INTRODUCTION
1.1 Background
Nowadays, natural fibers, which have many advantages, were investigated to replace
synthetic fibers. It will be economical if it is used as reinforcement in polymer
composites. An example of natural fibers is Empty Fruit Bunch Fibers (EFBF) that
has good potential reinforced polymer composites. (Rowell, R.M., et al., 1997).
The usages of EFBF as reinforcement in composite materials have gained interest
among scientists especially those in the South East Asia region where oil palm is a
major industrial cultivation. Pioneer work on the oil palm fibers were done by
Sreekala, et al., (1997). They conducted a thorough study on the morphology,
chemical composition, surface modifications and mechanical properties of oil palm
fibers alone.
With the increasing global energy crisis and ecological risks, plant fibers reinforced
polymer composites have attracted more and more research interests owing to their
potential of serving as alternative for artificial fiber composites (Bledzki, A.K.,
2002). Accordingly, extensive studies on preparation and properties of thermoplastic
and thermosetting composites filled with jute, bamboo, sisal, coir, hemp, flax,
pineapple and leaves were carried out. Compared with conventional glass fibers or
carbon fibers, plant fibers have many advantages like renewable, environmental
friendly, low cost, lightweight, high specific mechanical performance.
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Over the past decade there has been a growing interest in the use of lignocellulosic
fibers as reinforcing elements in polymeric matrix (Hamadag, H., et al., 1994). The
specific properties of these natural fibers are low cost, lightweight, renewable
character, high specific strength and modulus.
This study aims at introducing the natural fibers that used as fillers in a polymeric
matrix enabling production of economical and lightweight composites for load
carrying structures. In this study, it uses the EFBF in thermoplastic and not in
thermoset because of their good processability and ability to be recycled. Fillers are
added to the polymeric matrix with the aim of improving its thermal and mechanical
properties. There are, however, some adverse effects like toughness, and ultimate
elongation that polymers often suffer because of the addition of fillers.
Oil palm empty fruit bunch filled thermoplastic composites were studied by Rozman
et al. (1998). In their study, they observed that as the oil palm empty fruit bunch
filler loading increased in the high density polyethylene, the modulus of elasticity
and modulus of rupture of the composite increased and decreased respectively. The
tensile and impact properties were found to decrease with the increasing oil palm
empty fruit bunch filler in the composite. In addition, smaller sized empty fruit bunch
filler particles displayed higher modulus of elasticity and modulus of rupture
compared to larger filler particle size
A properly selected interface has a significant effect on the dispersion quality and
adhesion between the polymer and the filler. Natural hard fibers are gaining attention
as a reinforcing agent in thermoplastic matrices (Herrera, et al., 1997). Low density
and a highly reduced wear of the processing machinery may be mentioned as
attractive properties, together with their abundance and low cost. Cazaurang, et al.,
(1997) pointed out these hard fibers posses mechanical properties that make them a
suitable candidate to reinforce thermoplastic resins. Joseph, K., et al., (1993)
reported that hard fibers have been successfully incorporated into elastomers and
thermoplastics
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1.2 Problem Statement
Metal is one of the major structural applications on many fields in decades. Even
though the metal is one of the outstanding mechanical properties, the cost of their
raw material somehow overweigh inherits benefits. Nowadays, people always change
into the lightweight materials.
This situation has open the prospect to discover the possibility of producing
lightweight composite and at the same time try to improve the outstanding
mechanical properties. The cost of manufacturing is also can be reduced significantly
if the process of producing is in the simple step and they are produces locally within
the country area which is Malaysia.
In this research, the main focus is to use natural fiber which is EFBF as one of the
substitute materials for the steel, as the reinforcement in the polymer matrix in order
to produce high strength composite but lightweight. Nowadays, the EFBF can be
finding locally as one of the material to produce furniture like its counterpart the
wood and bamboo. This scenario gives the opportunity to investigate on producing
the lightweight composite since the cost for producing in Malaysia is in expensive
compared to the metals. The exploration in the bio-composite industry has
formulated its potential to be researched. So the usage of the metal is no longer
viable due to the threat of over cost of the materials that heavily depend on natural
source and mining activities
1.3 Objectives
The objectives of this research are:
(a) To study the mechanical and physical properties of EFBF as a filler or
reinforcement in composite.
(b) To identify the best composition of EFBF.
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1.4 Scope of Research
The scopes of this research are focuses to the materials, standard testing and suitable
processing. Study of the mechanical properties of EFBF and the best composition of
EFB fiber are important considerations in this research.
For the materials, it focuses to:
(a) Thermoplastic polymer like polypropylene (PP) as matrix for
composite fabrication
(b) Empty Fruit Bunch (EFB) as the reinforcement or filler
(c) Maleic Anhydride (MA) as coupling agent in additive to improve the
compatibility of interface reaction between plastic and EFB
For physical and mechanical properties of WPC, the standard testing is:
(a) Physical property test
(i) Moisture absorption test
(ii) Water absorption test
(iii) Flammability
(b) Mechanical property test
(i) Tensile strength
(ii) Flexural test
(iii) Hardness
For processing, the suitable machine is important with the right choices, which is:
(a) Hot Press Machine
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1.5 Rational for Research
In this research, EFBF is being investigated to replace the synthetic fiber to EFB
fibers. EFB is a waste fiber and have the criteria like the wood that is lignocelluloses.
The use of EFB filled thermoplastic material (PP) and mixing with additives (MAPP)
as a fabrication material or structural member has great potential. At the same time,
using low cost of reinforcement (EFB) and matrix will have the best mechanical
properties that improve the previous research in EFBF Composite application.
1.6 Thesis Frame
In this thesis frame, it explains the summary of each chapter from Chapter One to
Chapter Five. In Chapter One, it include the background of the study, problem
statement, objectives, scope and rational of research. For Chapter Two, the
explanation of composite material is based on its history, classification, major
properties, application and production processes. This chapter also covers the
manufacturing technologies which involve material and sample preparation
according to the types of process and machine selection. For Chapter Three, the
methodology includes the whole activities before produce the final EFB composite.
The procedure for this chapter is refer to the ASTM standard and the others
resources. While for Chapter 4, contains brief explanation and about the results and
analysis of the failure of the mechanical and physical properties of EFBF Composite,
is. For Chapter 5 is Conclusion and Recommendation of the study.
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CHAPTER 2
LITERATURE REVIEW
2.1 Composite Materials
Composites material consisting lignocellulosic fibers and synthetic thermoplastics
have received substantial attention in scientific literature as well as industry primarily
due to improvements in process technology and economic factor (Sanadi, A.R., et
al., 1992). The use of lignocellulosic in plastic composites is of particular interest
because such fibers can serve as a good reinforce and or filler for synthetic polymers
to enhance certain properties while reducing material cost (Kazayawoko, M., et al.,
1998).
2.1.1 Definition of Composite
Nowadays, composite materials are used in a wide variety of applications. According
to Astrom (1997), the noun composite is derived from the Latin verb componere
which means to put together. Therefore, a composite material can be considered as a
material which is formed when two or more chemically distinct constituents are
combined together on a macro scale (Astrom, 1977; Schwartz, 1992 and Jordan,
2002). Schwartz (1992) further stressed that the constituents in a composite material
can be physically identified and exhibit an interface between one another.
A more detailed description of a composite material was given by Agarwal et al.
(1981) who defined a composite as a material that consists of one or more
discontinuous phases which are usually hard and strong embedded in a continuous
phase. The continuous phase is called the matrix while the discontinuous phase is
termed the reinforcement material.
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Composite material is known as two or more materials to give a unique combination
of properties. The concept of composites was not only invented by human beings but
is already found in nature. An example, wood which is a composite of cellulose
fibers in a matrix of natural glue called lignin. The main concept of composite is that
it contains matrix material. Typically, composite material is formed by reinforcing
fibers in a matrix resin (Sanjay, K.M., 2000).
Based on definition of a composite material, composites can be produced by any
combination of two or more materials which can be metallic, organic or inorganic.
Schwartz, J.A., (1992) cited that the most widely used constituent forms in a
composite material are fibers, particles, lamina or layers, flakes, fillers and matrixes.
Generally, composite materials are classified based on the morphology of
reinforcement and also on the matrix material. Classifications of composite materials
according to the reinforcement forms are particulate reinforced composites, fiber
reinforced composites and structural composites.
2.1.2 Classifications of Composite Materials
Based on the definition of a composite material, composites can be produced by any
combination of two or more materials which can be metallic, organic or inorganic.
Schwartz (1992) cited that the most widely used constituent forms in a composite
material are fibers, particles, laminate or layers, flakes, fillers and matrixes.
Generally, composite materials are classified based on the morphology of
reinforcement and also on the matrix material. Classifications of composite materials
according to the reinforcement forms are particulate reinforced composites, fiber
reinforced composites and structural composites. Particles by definition are non-
fibrous in nature and have roughly equal dimensions. Fiber reinforced composites are
composed of reinforcing fibers which are a characterized as a long fine filament with
an aspect ratio of greater than 10. Glass, carbon, aramid, boron and cellulose fibers
are widely used as reinforcement in composite materials. Structural composites
though, consist of laminate and sandwich composites, which are used in structural
engineering applications.
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In addition, classification of composite materials based on the type of the matrix can
be grouped into there main categories such as metal matrix composites (MMC),
polymer matrix composites (PMC) and ceramic matrix composites (CMC)
(Schwartz, 1992; Hull et al., 1996 and Reinhart, 1987). According to Hull et al.
(1996) most composites in industrial use are based on polymeric matrices. The focus
of this study is mainly on polymer matrix composite in cellulose fiber.
2.2 Matrices
Matrix can be defined as a material where the reinforcing system of a composite is
embedded. The matrix serves as a binder which holds the reinforcing materials in its
place. Besides that, when a composite is subjected to an applied load, the matrix
deforms and transfers the external load uniformly to the fibers (Astrom, K.J., et al.,
1977). The matrix also provides resistance to crack propagation and damage
tolerance owing to the plastic flow at crack tips (Shwartz, 1992). Furthermore, the
matrix also functions to protect the surface of fibers from adverse environmental
effects and abrasion especially during composite processing. Plastic matrices can
generally be classified into two major types which are thermosets and thermoplastic
2.2.1 Thermoset
Thermoset resins are usually liquids or low melting point solids in their initial form.
This liquid resin is then converted to a hard rigid solid by chemical cross-linking
through a curing process which involves the application of heat and the addition of
curing agents or hardeners. Once cured, a tightly bound three dimensional network
structure is formed in the resin and hence the resin cannot be melted, reshaped and
reprocessed by heating (Hull, D., et al., 1996).
Therefore, during composite manufacturing, the impregnation process followed by
the shaping and solidification should be done before the resin begins to cure
(Mariatti, M., 1998). Thermoset resins are brittle at room temperature and have low
fracture toughness. On the other hand, owing to its three dimensional cross linked
structure, thermoset resins have high thermal stability, chemical resistance, high
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dimensional stability and also high creep properties (Matthews, E., et al., 1999). In
this study, thermoset is not used but study the thermoplastic resin.
2.2.2 Thermoplastic
Thermoplastic resins are linear or branched polymers which remain as a solid at
room temperature. Unlike thermosets, thermoplastics do not form a three
dimensional cross linking network. The monomer units in the thermoplastic are held
by a weak Van der Wall‟s forces which are easily broken by heat and stress
(Dominick, D., 1997). As a result, thermoplastics are able to melt when heated and
becomes a solid when cooled to room temperature.
Thermoplastic resins offer several advantages over their thermoset resin counterpart.
Thermoplastic products can be recycled owing to the nature of the thermoplastics
which can be repeatedly heated and shaped (Ruzaidi, 1999 and Matthews et al.,
1999). In addition, thermoplastics offer improved fracture toughness and low
moisture absorption behavior.
The processing time of thermoplastics is shorter than most thermosets as the
processing of thermoplastics only involve melting, shaping and cooling which can be
achieved in a matter of few seconds whereas thermosets would take several hours to
days to fully crosslink (Leong, K.H., 2003). Moreover, imperfect thermoplastic
products can be reprocessed and flash or unused thermoplastics can be used for other
applications.
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