A Study Of Mechanical Properties In Relation With Morphological Structure Of PP/Kenaf Fiber Reinforced Plastic Composite.
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
A STUDY OF MECHANICAL PROPERTIES IN RELATION WITH
MORPHOLOGICAL STRUCTURE OF PP/KENAF FIBER
REINFORCED PLASTIC COMPOSITE
This report submitted in accordance with requirement of the Universiti Teknikal
Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Materials Engineering) with Honours.
by
NOOR SYAFIQ BIN SHAARI
FACULTY OF MANUFACTURING ENGINEERING
2009
ABSTRACT
This research aims to study and analyze the effects of different fiber loading and
coupling agent addition on the mechanical properties and its relationship to the micro
structural behavior of the kenaf fiber reinforced polypropylene composites. The main
raw materials used in this project are polypropylene (PP) resin as matrix materials and
kenaf fiber as reinforcement materials for the composite fabrication. Typically, the
observed size of kenaf fibers used in this study is around 513.39µm. The composite
panels were fabricated by using an internal mixer and compression molding machine
and were then cut into the specific dimension according to the specific ASTM standard
of testing. The specimens primarily were tested for the Critical Properties Analysis Tensile Test. The best compounding formulation of composite was found at the weight
percentage (wt%) of 60wt% of PP matrix and 40wt% of the kenaf fibers. Further
analyses for various mechanical properties of the composite were done accordingly to
all composites formulation. The microstructures of tested specimens fracture surface
were observed as to understand the fracture behavior, the fiber distribution and the
surface morphology and its significant correlation to the mechanical properties studied.
The results showed that the increasing of fiber loading had significantly increased the
mechanical properties of the fabricated composite. The introduction of 3wt% of
polypropylene-graft-maleic anhydride (MAPP) was done to the best formulated
composites which indicate the improvement of the interfacial adhesion between the
fiber-matrix interphase through the morphology observed and also improvement in the
properties studied especially in water absorption behavior. Through the study, the
enhancement of fabricated composite could be applied to the structural engineering
applications through the advantage of the mechanical properties performance of tensile,
flexural and impact properties.
i
ABSTRAK
Matlamat penulisan kertas kerja ini adalah untuk mengkaji dan menganalisis kesan
penambahan gentian dan agen perangkai serta hubungan struktur mikro pada sifat
mekanik komposit gentian kenaf yang diperkuatkan dengan polipropilena. Bahan utama
yang digunakan di dalam kajian ini adalah resin polipropilena (PP) sebagai bahan matrik
dan gentian kenaf sebagai bahan penenulangan komposit. Saiz gentian kenaf yang
digunakan dalam kajian ini adalah dalam lingkungan 513.39µm. Kepingan komposit
dibentuk dengan menggunakan mesin pencampuran dalaman serta mesin pemampat dan
kemudiannya dipotong mengikut spesifikasi tertentu berdasarkan piawaian ujian ASTM.
Pada permulaannya, spesimen-spesimen diuji pada Analisa Sifat Kritikal iaitu ujian
tegangan. Formula sebatian terbaik komposit didapati pada peratusan berat (wt%)
dengan 60wt% matrik PP dan 40wt% gentian kenaf. Analisa lanjutan pelbagai sifat
mekanik komposit diteruskan terhadap semua formula sebatian. Struktur mikro pada
permukaan spesimen yang telah retak dikaji dalam memahami sifat rekahan, taburan
gentian dan morfologi permukaan serta hubungannya terhadap kajian sifat mekanik.
Keputusan menunjukkan bahawa dengan peningkatan pertambahan gentian telah
meningkatkan sifat-sifat mekanik komposit. Pengenalan polypropylene-graft-maleic
anhydride, (MAPP) dilakukan terhadap formula sebatian terbaik komposit yang
menunjukkan penambahbaikan terhadap lekatan antara muka di antara matrik-gentian
melalui pemerhatian morfologi dan juga peningkatan sifat mekanik komposit
terutamanya sifat penyerapan air. Melalui kajian ini juga, penambahbaikan terhadap
sifat mekanik komposit diharap dapat diaplikasikan dengan penggunaan di dalam
industri melalui kelebihan pencapaian dalam sifat tegangan, sifat lenturan dan sifat
hentaman komposit.
ii
DEDICATION
For my beloved family and friends
iii
ACKNOWLEDGEMENT
I would like to convey my thanks to the all person who had contributed in ensuring a
successful occurrence throughout the duration of my final year project (PSM I). I also
gratefully acknowledge to my ex-supervisor, Mrs. Zurina binti Shamsudin, my
supervisor Mr. Jefferie bin Abd Razak and my previous and my current examiners Mr.
Edeerozey bin Abd. Manaf and Associated Professor Dr Thangaraj Joseph Sahaya
Anand for their encouragement, fully support, by providing me enormous guidance and
idea for my research project. Without them all, this project may not valuable. Their
knowledge and experience has fully inspired, motivated and drive me to complete my
final year project successfully. Also, my special thanks to Mr. Hairulhisham bin Rosnan,
for your time and co-operation completing my research project. Subsequently to Mohd
Azhar Bin Abu Shah and all technicians involved to complete this project. To all my
peers, especially those who are undergoing final year in Degree programs, thanks for
your all kindness of delivering ideas and motivation that necessary for me to complete
this study. Besides those mentioned, I also would like to express my gratitude with
highly appreciation and dedication to my family because without them, I won’t be here
to complete my study in Universiti Teknikal Malaysia, Melaka.
iv
TABLE OF CONTENTS
Abstract
i
Abstrak
ii
Dedication
iii
Acknowledgement
iv
Table of Contents
v
List of Tables
ix
List of Figures
x
List of Abbreviations, Symbols, Specialized Nomenclature
xiv
1. INTRODUCTION
1
1.1
Background of study
1
1.2
Problem Statements
3
1.3
Objectives
4
1.4
Hypotheses
5
1.5
Scope of study
5
2. LITERATURE REVIEW
7
2.1
Introduction
7
2.2
Composite
7
2.2.1
Introduction to Composite
7
2.2.2
Polymer Matrix Composite (PMC)
9
2.3
Matrix
2.3.1
2.4
10
Polypropylene (PP) as Matrix Material
11
Reinforcement
12
2.4.1
Natural fiber
13
2.4.1.1 Kenaf fiber
15
2.5
Processing of composites
18
2.6
Rules of Mixture (RoM)
19
v
2.6.1 Elastic Modulus
19
2.6.2 Density
20
2.7
Fiber loading
21
2.8
Tensile and flexural properties
22
2.9
Impact properties
24
2.10
Water absorption
25
2.11
Coupling Agent
27
2.12
Morphological study
31
3. METHODOLOGY
33
3.1
Introduction
33
3.2
Materials
34
3.2.1
Polypropylene (PP)
34
3.2.2
Kenaf short fiber (core)
36
3.3
3.4
3.5
3.6
3.2.3 Coupling agents
37
Raw materials preparation
38
3.3.1 Crushing
38
3.3.2
38
Kenaf fiber drying process
Characterization of kenaf short fiber
39
3.4.1
39
Density measurement
3.4.2 Water absorption
40
3.4.3
Drying profile study
40
3.4.4
Microscopy study
40
Sample fabrication
41
3.5.1
Compounding of PP/kenaf composite
41
3.5.2
Introduction of Coupling Agent
43
3.5.3
Hot and cold compression molding
43
Mechanical testing
44
3.6.1
Critical Properties Analysis – Tensile Test
44
3.6.2
Flexural Test
45
3.6.3
Izod Pendulum Impact Test
46
vi
3.6.4
Water Absorption Test
47
3.6.5
Thickness Swelling Test
47
3.6.6
Morphological study
48
4. RESULTS
49
4.1
Introduction
49
4.2
Characterization
49
4.2.1
49
Fiber size
4.2.2 Density
50
4.2.3
51
Drying study
4.3
Observation of Sample Preparation Process
52
4.4
Critical Property Analysis - Tensile Test
53
4.4.1
55
4.5
4.6
Fracture Surface Morphology of Tensile Specimen
Flexural Test
59
4.5.1
61
Bending Surface Morphology of Flexural Specimen
Impact Test
65
4.6.1
67
Fracture Surface Morphology of Impact Specimen
4.7
Water Absorption Testing
70
4.8
Thickness Swelling Testing
72
5. DISCUSSION
75
5.1
Introduction
75
5.2
Tensile Properties
75
5.3
Flexural Properties
82
5.4
Impact Properties
87
5.5
Water Absorption and Thickness Swelling Behavior
90
6. CONCLUSION AND RECOMMENDATION
92
6.1
Conclusion
92
6.2
Recommendation
94
vii
REFERENCES
95
APPENDIX
A
Gantt chart for PSM I
100
B
Gantt chart for PSM II
101
C
Micrograph of Kenaf Fibers size
102
D
Data of Kenaf Fiber Size Analysis
103
E
Sample designation by weight percentage (wt %)
104
viii
LIST OF TABLES
2.1
Comparison of Thermoplastics and Thermosets polymer
2.2
Comparison of Properties of Kenaf-Filled PP with typical
12
commercially filled PP composites
13
2.3
Comparison between natural fiber and synthetic fiber
14
2.4
Scientific classification of kenaf plant
16
2.5
Chemical composition in Kenaf fiber
17
2.6
Results on mechanical test on various PP/kenaf composite blends
30
3.1
Physical properties of the polypropylene (PP)
36
3.2
Technical properties of Polypropylene-graft-maleic anhydride (MAPP)
37
4.1
Measurement of kenaf fiber density
51
4.2
Total of weight loss of kenaf short fiber of the drying process
51
4.3
Tensile properties of pure PP and PP/kenaf fiber composite with
the absence and presence of MAPP
4.4
54
Flexural properties of pure PP and PP/kenaf fiber composite with
the absence and presence of MAPP
4.5
60
Impact properties of pure PP and PP/kenaf fiber composite with
the absence and presence of MAPP
4.6
66
Weight deflection and Percentage of weight gain of specimens
at the different composition of kenaf fiber addition
4.7
71
Thickness deflection and Percentage of thickness swelling of specimens
at the different composition of kenaf fiber addition
ix
73
LIST OF FIGURES
2.1
A classification scheme for the various composites types
8
2.2
Molecular structure of PP
11
2.3
Parts of Kenaf Plant
15
2.4
Configuration of kenaf fiber
17
2.5
Stress-strain curves of the kenaf sheet, the PLLA film and the
PLLA/kenaf composite
22
2.6
Relationship between tensile properties and fiber content
23
2.7
Relationship between flexural properties and fiber content
23
2.8
Effect of the amount kenaf versus the notched and un-notched
Izod impact strength of PP/kenaf coupled composites with 2% of
weight of coupling agent
25
2.9
Water absorption of natural and glass fiber composites (untreated)
26
2.10
Water absorption of natural fiber composites (treated)
26
2.11
Hypothetical reaction of silanol and the fiber
28
2.12
Proposed reaction mechanism for compatibilization
28
2.13
Stress-strain curves of typical kenaf filled coupled composites with 2%
2.14
of weight of coupling agent
29
Reaction steps in silane grafting of bio fiber surface
30
2.15A SEM micrographs of kenaf fiber surface in composites 100µm
(at 200x)
31
2.15B SEM micrographs of kenaf fiber surface in composites 10µm
(at 500x)
31
2.16a SEM micrographs of the tensile fracture surface of PP/kenaf (20%)
without MAPP
32
2.16b SEM micrographs of the tensile fracture surface of PP/kenaf (20%)
with MAPP
32
2.17a SEM micrograph of an untreated kenaf fiber
32
2.17b SEM micrograph of 3% NaOH treated kenaf fiber
32
x
3.1
Polypropylene Pellets
34
3.2
Flow chart of methodology
35
3.3
Kenaf fibers
36
3.4
Polypropylene-graft-maleic anhydride (MAPP)
37
3.5
Rotor mill machine
38
3.6
Dried kenaf fiber
39
3.7
Electronic Densimeter MD-300S
39
3.8
Scanning Electron Microscopy SEM EVO 50
41
3.9
Internal mixer HAAKE Rheomix OS
42
3.10
Hot Press machine G0-7014-A30
43
3.11
Universal Testing Machine UTM
44
3.12
Flexural Testing at three-point bending process
45
3.13
Standard test configuration of flexural test
46
3.14
Standard test configuration of Impact Test
46
3.15
Specimens mounted on the SEM stubs
48
4.1
Morphology of the kenaf fibers
50
4.2
Total weight loss of the kenaf short fiber in gram (g) of the drying process 52
4.3
Tensile Strength of the PP/Kenaf/MAPP composite
at different composition
4.4
54
Tensile Modulus of the PP/Kenaf/MAPP composite at different
composition
4.5
55
The SEM image of the fractured surface of pure PP at the 1000x
of magnification
4.6
56
The SEM image of the fractured surface of PP/kenaf composite with
10wt% of kenaf addition at the 1000x of magnification
4.7
The SEM image of the fractured surface of PP/kenaf composite with
20wt% of kenaf addition at the 1000x of magnification
4.8
57
57
The SEM image of the fractured surface of PP/kenaf composite with
30wt% of kenaf addition at the 1000x of magnification
xi
58
4.9
The SEM image of the fractured surface of PP/kenaf composite with
40wt% of kenaf addition at the 1000x of magnification
4.10
58
The SEM image of the fractured surface of PP/kenaf composite with
40wt% of kenaf addition and 3wt% of MAPP at the 1000x
of magnification
4.11
59
Flexural Strength of the PP/Kenaf/MAPP composite at different
composition
4.12
60
Flexural Modulus of the PP/Kenaf/MAPP composite at different
composition
4.13
61
The SEM image of the bending surface for pure PP at the 3000x
of magnification
4.14
62
The SEM image of the bending surface for PP/kenaf composite with
10wt% of kenaf fiber addition at the 1000x of magnification
4.15
The SEM image of the bending surface for PP/kenaf composite with
20wt% of kenaf fiber addition at the 1000x of magnification
4.16
66
The SEM image of the fractured surface for pure PP at the 1000x
of magnification
4.21
67
The SEM image of the fractured surface for PP/kenaf composite with
10wt% of kenaf fiber addition at the 1000x of magnification
4.22
68
The SEM image of the fractured surface for PP/kenaf composite with
20wt% of kenaf fiber addition at the 1000x of magnification
4.23
65
Impact Strength of the PP/Kenaf/MAPP composite at different
composition
4.20
64
The SEM image of the bending surface for PP/kenaf composite with
40wt% of kenaf fiber and 3wt% of MAPP at the 500x of magnification
4.19
64
The SEM image of the bending surface for PP/kenaf composite with
40wt% of kenaf fiber addition at the 1000x of magnification
4.18
63
The SEM image of the bending surface for PP/kenaf composite with
30wt% of kenaf fiber addition at the 1000x of magnification
4.17
63
68
The SEM image of the fractured surface for PP/kenaf composite with
30wt% of kenaf fiber addition at the 1000x of magnification
xii
69
4.24
The SEM image of the fractured surface for PP/kenaf composite with
40wt% of kenaf fiber addition at the 500x of magnification
4.25
69
The SEM image of the fractured surface for PP/kenaf composite with
40wt% of kenaf fiber addition and 3wt% of MAPP at the 350x
of magnification
4.26
70
Percentages of weight gain at the ambient temperature after 24 hours
immersion for different specimen composition
4.27
Percentages of thickness swelling at the ambient temperature after
24 hours immersion for different specimen composition
5.1
78
Tensile Properties and Morphological Behavior (1000 X Magnification)
of the pure PP and PP/Kenaf composites
5.3
82
Flexural Properties and Morphological Behavior (1000 X Magnification)
of the pure PP and PP/Kenaf/MAPP composites
5.6
86
Impact Strength and Morphological Behavior (1000 X Magnification)
of the pure PP and PP/Kenaf/MAPP composites
5.8
85
Flexural Properties and Morphological Behavior (1000 X Magnification)
of the PP/Kenaf/MAPP composites
5.7
81
SEM Fractured Surface for PP/Kenaf reinforced composite with
40wt% of kenaf fiber
5.5
79
Tensile Properties and Morphological Behavior (1000 X Magnification)
of the PP/Kenaf/MAPP composites
5.4
74
SEM morphology of the PP/Kenaf reinforced composite with
the introduction of 3wt% of MAPP
5.2
72
88
Impact Strength and Morphological Behavior (1000 X Magnification)
of the PP/Kenaf/MAPP composites
xiii
89
LIST OF ABBREVIATIONS, SYMBOLS, SPECIALIZED
NOMENCLATURE
200x
-
200 times magnification
%
-
Percent
0
-
Degrees Celsius
Ρ
-
Density
σ/ρ
-
Tensile Strength per unit mass (specific strength)
E/ρ
-
Tensile Modulus per unit mass (specific modulus)
-OH
-
Hydroxyl
AMPTES
-
3-aminopropyl-triethoxysilane
APS
-
3-aminopropyl-triethoxysilane
ASTM
-
American Society for Testing and Materials
CCC
-
Carbon-Carbon Composite
CMC
-
Ceramic-Matrix Composite
EcL
-
Longitudinal Young Modulus of Composite
EcT
-
Transverse Young Modulus of Composite
eg.
-
Example
et al.
-
and others
etc.
-
Et cetera
FRP
-
Fiber-reinforced plastics
g/cm3
-
Gram per Centimeter Cube
GPa
-
Giga Pascal
i.e.,
-
That is
J
-
Joule
Kw
-
Kilowatt
(M)
-
Malaysia
MAPP
-
Maleic-Anhydride Grafted Polypropylene
MAPP
-
Polypropylene-graft-maleic anhydride
C
xiv
min
-
Minutes
mm
-
Milimeter
mm/min
-
Milimeter per minute
µm
-
Micrometer
MMC
-
Metal-Matrix Composite
MPa
-
Mega Pascal
N
-
Newton
NF
-
Natural Fiber
N/mm2
-
Newton millimeter square
NaOH
-
Sodium Hydroxide
OH
-
Hydroxyl
PE
-
Polyethylene
PLLA
-
Poly-L-lactic acid
PMC
-
Polymer Matrix Composite
PP
-
Polypropylene
PP/kenaf
-
Kenaf Fiber Reinforced Polypropylene Composite
PS
-
Polystyrene
RoM
-
Rules of Mixtures
rpm
-
Revolution per minute
SEM
-
Scanning Electron Microscope
UTM
-
Universal Testing Machine
UV
-
ultraviolet
wt%
-
Percent of weight fraction
xv
CHAPTER 1
INTRODUCTION
1.1
Background of Study
Recently, the used of fiber-reinforced plastics (FRP) composite becomes famous in
manufacturing industry. The primary advantages of using fiber as filler/reinforcement in
plastics are low densities, non abrasive high filling levels possible resulting in high
stiffness properties, high specific properties, easily recyclable, the fibers will not
fractured when processing over sharp curvatures, biodegradable, low energy
consumption and low cost of production (Kahraman et al., 2005). Throughout its
performance, FRP composites play a vital role in consumer needs or products that
exhibits high level of mechanical properties. The main purpose of using the FRP
composites is to improve the mechanical properties of existing polymeric materials. The
FRP composite can be defined as a material consists of polymer such as Polypropylene
(PP), Polyethylene (PE), Polystyrene (PS) and etc. as matrix and fiber as reinforcement.
Each matrix or reinforcement type can be distinct because of its physical or mechanical
properties, materials form and chemical composition.
Products in a monolithic material are widely used in a daily life such as bottle, food
packaging, vehicles, piping, electronic and etc. These examples of plastics product were
specifically produced by using PP, PE, and PS. However, the manipulation of
monolithic polymer materials as daily life products are not exhibits the high
performances especially in vehicles and electronics application. High impact resistance
is necessary for vehicles and high melting temperature is needed for electronic part
1
(Paul et al., 2008). Melting temperature for PP which is 175ºC has proved that it is not
suitable to be used in electronic and engine vehicles which commonly operated at
higher temperature of service (Kalpakjian and Schmid, 2006; Callister, 2003).
Therefore, the introduction to the fabrication of composites which utilizes the
advantages of fiber reinforcement should capable to improve the performances compare
to monolithic polymeric material, especially in highly demanding application like
automotives and electronics application.
There are two types of fiber commonly used in composites which are natural fiber and
synthetic fiber. Both types of fiber got higher potential to be used as a reinforcement
agent in composite materials. For low cost of production and widely availability of
fiber, natural fiber had been chosen for this study. Natural fiber had played important
roles in enhancing the composites performance. Kenaf, Jute, and Hemp namely as
natural fiber were widely used as reinforcement for composites. In addition, the
performance of the natural fiber, especially kenaf has proved by researchers previously
as the multipurpose used materials because of kenaf plant itself include the stalks (bast
and core), leaves and seeds to be produced as useful material in manufacturing industry.
Beyond the new uses for kenaf including its utilization in building material, absorbents,
household, and vehicles, the commercial success of kenaf has great potential economic
and environmental benefits in replacement or reduced use of fiberglass in industrial
products and the increased used of recycled plastics (Webber et al., 2002). However,
there were also disadvantages of using natural fiber in thermoplastics through its lignocellulosic properties which are the high moisture absorption of the fibers and the low
processing temperature permissible during the fabrication process (Sanadi et al., 1995).
In order to increase the performances and properties of fabricated composites, the
compatibilizer should be introduced. Various types of chemical reagents have been used
in previous study by researchers such as silane, Maleic-Anhydride Grafted
Polypropylene (MAPP), alkoxysilane and etc. Besides the using of Silane, Maleated
coupling agents are widely used as its main function to enhance the interactions
2
between the matrix and fiber and to strengthen composites containing fillers and fiber
reinforcement (Keener et al., 2004). Therefore, the introduction of MAPP as
compatibilizer has been employed through the study in order to improve the mechanical
properties of the fabricated composites.
1.2
Problem Statements
It is important and possible to produce a new types of material that exhibit the
economically and environmentally benefits for the applications in automotive, building,
furniture and packaging industries. By combining the different resources, it is possible
to blend, mix or process the natural fiber with other elements such as glass, plastics and
synthetics material to produces new classes of materials (Sanadi et al., 1990).
Biodegradable or environmentally acceptable materials have attained increasing interest
in few decades to the researchers and manufactures due to the environmental pressure
derived from the consumption of petroleum-based materials, difficulties in degrade in a
landfill and composting environments (Liu et al., 2006; Huda et al., 2007). Thus, the
introduction of natural fiber such as kenaf, hemp, ramie and flex has attractively
influenced the production of biodegradable materials lately, especially in manufacturing
industry (Bledski et al., 2002).
Natural fiber like kenaf can be used as replacement to the conventional fiber. Global
environmental issues have led to a renewed interest in bio-based materials like fiber
glass or carbon fiber; which the focus on renewable raw materials can be biodegradable
or recyclable at reasonable cost (Hong et al., 2007; Zampaloni et al., 2007). The
problem faced by the researchers and manufacturers is to find the good natural fiber for
polymer composite application equipped with the most promising and outstanding
mechanical and physical properties. The uses of natural plant fibers as a reinforcement
materials to replace synthetic fibers is receiving great attention, due to the advantages of
renewability, low density and high specific strength (Ochi, 2008). These fiber
3
outstanding properties such as high specific strength in stiffness, impact resistance,
flexibility, and modulus make them an attractive alternative over the traditional
materials (Sgriccia et al., 2008). Specifically, the good properties of kenaf fiber include
good specific strengths and modulus, economical viability, low density and low weight
has make them as a reinforcement of choice by industry.
The low processing temperature permissible to the ligno-cellulosic fiber in
thermoplastics is limited due to fiber degradation at higher processing temperatures
(Sanadi et al., 1995). It is important to ensure that the fabrication are employed in the
controlled temperature processing, because the degradation of the kenaf fiber will lead
to the failure or poor performance to the properties of the fabricated composite.
Therefore, the chosen suitable processing temperature is important consideration
accordance to the fabrication of PP/kenaf composites.
1.3
Objectives
The purpose of this study is:
a) To study the effects of different fibers loading of kenaf (wt %) to the mechanical
properties of the fiber reinforced polypropylene composite;
b) To study the effects of proposed compatibilizer on the fabrication of PP/kenaf
fiber and compare its effect to the properties enhancement of the fabricated
composites.
4
1.4
i).
Hypotheses
The different filler loading or proportion of kenaf short fiber used for this study
will affect the mechanical properties of the composite. It is expected that, by
increasing the proportion of filler loading, mechanical properties of the
fabricated composite must be also increased correspondingly in accordance with
the rules of mixture theory.
ii).
Introduction of compatibilizer in this study will increased the mechanical
properties of the fabricated composites. The good interfacial adhesion formed
between the surface interaction of kenaf fiber and PP matrix is expected to
improve the properties of composites materials.
1.5
Scope of study
The study was started by preparing and characterizing the kenaf fiber as raw materials
to be used as reinforcement material in the fabrication of PP/kenaf composite. The
materials used that related in this study are polypropylene (PP) pellets and kenaf short
fibers. The kenaf short fibers were prepared by using the rotor mill to get the various
size of fiber length. The size and density of the fiber reinforced were determined by
using Scanning Electron Microscope (SEM) model EVO 5 and Electronic Densimeter
model MD300-S, respectively. However, the kenaf properties are difficult to measure,
thus no preliminary study on the kenaf properties was carried out during this research
(Sanadi et al., 1995).
Next stage of process involves the drying study of kenaf fiber. Kenaf fibers will be
dried in the drying oven for seven hours period of time and the weight losses of fibers
were weighed for every hour. The effects of fiber loading for kenaf short fiber on
polypropylene composites were investigates by varying the weight percentage (wt%)
for both materials. There are five fraction of fiber loading will be employed in this study
5
A STUDY OF MECHANICAL PROPERTIES IN RELATION WITH
MORPHOLOGICAL STRUCTURE OF PP/KENAF FIBER
REINFORCED PLASTIC COMPOSITE
This report submitted in accordance with requirement of the Universiti Teknikal
Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Materials Engineering) with Honours.
by
NOOR SYAFIQ BIN SHAARI
FACULTY OF MANUFACTURING ENGINEERING
2009
ABSTRACT
This research aims to study and analyze the effects of different fiber loading and
coupling agent addition on the mechanical properties and its relationship to the micro
structural behavior of the kenaf fiber reinforced polypropylene composites. The main
raw materials used in this project are polypropylene (PP) resin as matrix materials and
kenaf fiber as reinforcement materials for the composite fabrication. Typically, the
observed size of kenaf fibers used in this study is around 513.39µm. The composite
panels were fabricated by using an internal mixer and compression molding machine
and were then cut into the specific dimension according to the specific ASTM standard
of testing. The specimens primarily were tested for the Critical Properties Analysis Tensile Test. The best compounding formulation of composite was found at the weight
percentage (wt%) of 60wt% of PP matrix and 40wt% of the kenaf fibers. Further
analyses for various mechanical properties of the composite were done accordingly to
all composites formulation. The microstructures of tested specimens fracture surface
were observed as to understand the fracture behavior, the fiber distribution and the
surface morphology and its significant correlation to the mechanical properties studied.
The results showed that the increasing of fiber loading had significantly increased the
mechanical properties of the fabricated composite. The introduction of 3wt% of
polypropylene-graft-maleic anhydride (MAPP) was done to the best formulated
composites which indicate the improvement of the interfacial adhesion between the
fiber-matrix interphase through the morphology observed and also improvement in the
properties studied especially in water absorption behavior. Through the study, the
enhancement of fabricated composite could be applied to the structural engineering
applications through the advantage of the mechanical properties performance of tensile,
flexural and impact properties.
i
ABSTRAK
Matlamat penulisan kertas kerja ini adalah untuk mengkaji dan menganalisis kesan
penambahan gentian dan agen perangkai serta hubungan struktur mikro pada sifat
mekanik komposit gentian kenaf yang diperkuatkan dengan polipropilena. Bahan utama
yang digunakan di dalam kajian ini adalah resin polipropilena (PP) sebagai bahan matrik
dan gentian kenaf sebagai bahan penenulangan komposit. Saiz gentian kenaf yang
digunakan dalam kajian ini adalah dalam lingkungan 513.39µm. Kepingan komposit
dibentuk dengan menggunakan mesin pencampuran dalaman serta mesin pemampat dan
kemudiannya dipotong mengikut spesifikasi tertentu berdasarkan piawaian ujian ASTM.
Pada permulaannya, spesimen-spesimen diuji pada Analisa Sifat Kritikal iaitu ujian
tegangan. Formula sebatian terbaik komposit didapati pada peratusan berat (wt%)
dengan 60wt% matrik PP dan 40wt% gentian kenaf. Analisa lanjutan pelbagai sifat
mekanik komposit diteruskan terhadap semua formula sebatian. Struktur mikro pada
permukaan spesimen yang telah retak dikaji dalam memahami sifat rekahan, taburan
gentian dan morfologi permukaan serta hubungannya terhadap kajian sifat mekanik.
Keputusan menunjukkan bahawa dengan peningkatan pertambahan gentian telah
meningkatkan sifat-sifat mekanik komposit. Pengenalan polypropylene-graft-maleic
anhydride, (MAPP) dilakukan terhadap formula sebatian terbaik komposit yang
menunjukkan penambahbaikan terhadap lekatan antara muka di antara matrik-gentian
melalui pemerhatian morfologi dan juga peningkatan sifat mekanik komposit
terutamanya sifat penyerapan air. Melalui kajian ini juga, penambahbaikan terhadap
sifat mekanik komposit diharap dapat diaplikasikan dengan penggunaan di dalam
industri melalui kelebihan pencapaian dalam sifat tegangan, sifat lenturan dan sifat
hentaman komposit.
ii
DEDICATION
For my beloved family and friends
iii
ACKNOWLEDGEMENT
I would like to convey my thanks to the all person who had contributed in ensuring a
successful occurrence throughout the duration of my final year project (PSM I). I also
gratefully acknowledge to my ex-supervisor, Mrs. Zurina binti Shamsudin, my
supervisor Mr. Jefferie bin Abd Razak and my previous and my current examiners Mr.
Edeerozey bin Abd. Manaf and Associated Professor Dr Thangaraj Joseph Sahaya
Anand for their encouragement, fully support, by providing me enormous guidance and
idea for my research project. Without them all, this project may not valuable. Their
knowledge and experience has fully inspired, motivated and drive me to complete my
final year project successfully. Also, my special thanks to Mr. Hairulhisham bin Rosnan,
for your time and co-operation completing my research project. Subsequently to Mohd
Azhar Bin Abu Shah and all technicians involved to complete this project. To all my
peers, especially those who are undergoing final year in Degree programs, thanks for
your all kindness of delivering ideas and motivation that necessary for me to complete
this study. Besides those mentioned, I also would like to express my gratitude with
highly appreciation and dedication to my family because without them, I won’t be here
to complete my study in Universiti Teknikal Malaysia, Melaka.
iv
TABLE OF CONTENTS
Abstract
i
Abstrak
ii
Dedication
iii
Acknowledgement
iv
Table of Contents
v
List of Tables
ix
List of Figures
x
List of Abbreviations, Symbols, Specialized Nomenclature
xiv
1. INTRODUCTION
1
1.1
Background of study
1
1.2
Problem Statements
3
1.3
Objectives
4
1.4
Hypotheses
5
1.5
Scope of study
5
2. LITERATURE REVIEW
7
2.1
Introduction
7
2.2
Composite
7
2.2.1
Introduction to Composite
7
2.2.2
Polymer Matrix Composite (PMC)
9
2.3
Matrix
2.3.1
2.4
10
Polypropylene (PP) as Matrix Material
11
Reinforcement
12
2.4.1
Natural fiber
13
2.4.1.1 Kenaf fiber
15
2.5
Processing of composites
18
2.6
Rules of Mixture (RoM)
19
v
2.6.1 Elastic Modulus
19
2.6.2 Density
20
2.7
Fiber loading
21
2.8
Tensile and flexural properties
22
2.9
Impact properties
24
2.10
Water absorption
25
2.11
Coupling Agent
27
2.12
Morphological study
31
3. METHODOLOGY
33
3.1
Introduction
33
3.2
Materials
34
3.2.1
Polypropylene (PP)
34
3.2.2
Kenaf short fiber (core)
36
3.3
3.4
3.5
3.6
3.2.3 Coupling agents
37
Raw materials preparation
38
3.3.1 Crushing
38
3.3.2
38
Kenaf fiber drying process
Characterization of kenaf short fiber
39
3.4.1
39
Density measurement
3.4.2 Water absorption
40
3.4.3
Drying profile study
40
3.4.4
Microscopy study
40
Sample fabrication
41
3.5.1
Compounding of PP/kenaf composite
41
3.5.2
Introduction of Coupling Agent
43
3.5.3
Hot and cold compression molding
43
Mechanical testing
44
3.6.1
Critical Properties Analysis – Tensile Test
44
3.6.2
Flexural Test
45
3.6.3
Izod Pendulum Impact Test
46
vi
3.6.4
Water Absorption Test
47
3.6.5
Thickness Swelling Test
47
3.6.6
Morphological study
48
4. RESULTS
49
4.1
Introduction
49
4.2
Characterization
49
4.2.1
49
Fiber size
4.2.2 Density
50
4.2.3
51
Drying study
4.3
Observation of Sample Preparation Process
52
4.4
Critical Property Analysis - Tensile Test
53
4.4.1
55
4.5
4.6
Fracture Surface Morphology of Tensile Specimen
Flexural Test
59
4.5.1
61
Bending Surface Morphology of Flexural Specimen
Impact Test
65
4.6.1
67
Fracture Surface Morphology of Impact Specimen
4.7
Water Absorption Testing
70
4.8
Thickness Swelling Testing
72
5. DISCUSSION
75
5.1
Introduction
75
5.2
Tensile Properties
75
5.3
Flexural Properties
82
5.4
Impact Properties
87
5.5
Water Absorption and Thickness Swelling Behavior
90
6. CONCLUSION AND RECOMMENDATION
92
6.1
Conclusion
92
6.2
Recommendation
94
vii
REFERENCES
95
APPENDIX
A
Gantt chart for PSM I
100
B
Gantt chart for PSM II
101
C
Micrograph of Kenaf Fibers size
102
D
Data of Kenaf Fiber Size Analysis
103
E
Sample designation by weight percentage (wt %)
104
viii
LIST OF TABLES
2.1
Comparison of Thermoplastics and Thermosets polymer
2.2
Comparison of Properties of Kenaf-Filled PP with typical
12
commercially filled PP composites
13
2.3
Comparison between natural fiber and synthetic fiber
14
2.4
Scientific classification of kenaf plant
16
2.5
Chemical composition in Kenaf fiber
17
2.6
Results on mechanical test on various PP/kenaf composite blends
30
3.1
Physical properties of the polypropylene (PP)
36
3.2
Technical properties of Polypropylene-graft-maleic anhydride (MAPP)
37
4.1
Measurement of kenaf fiber density
51
4.2
Total of weight loss of kenaf short fiber of the drying process
51
4.3
Tensile properties of pure PP and PP/kenaf fiber composite with
the absence and presence of MAPP
4.4
54
Flexural properties of pure PP and PP/kenaf fiber composite with
the absence and presence of MAPP
4.5
60
Impact properties of pure PP and PP/kenaf fiber composite with
the absence and presence of MAPP
4.6
66
Weight deflection and Percentage of weight gain of specimens
at the different composition of kenaf fiber addition
4.7
71
Thickness deflection and Percentage of thickness swelling of specimens
at the different composition of kenaf fiber addition
ix
73
LIST OF FIGURES
2.1
A classification scheme for the various composites types
8
2.2
Molecular structure of PP
11
2.3
Parts of Kenaf Plant
15
2.4
Configuration of kenaf fiber
17
2.5
Stress-strain curves of the kenaf sheet, the PLLA film and the
PLLA/kenaf composite
22
2.6
Relationship between tensile properties and fiber content
23
2.7
Relationship between flexural properties and fiber content
23
2.8
Effect of the amount kenaf versus the notched and un-notched
Izod impact strength of PP/kenaf coupled composites with 2% of
weight of coupling agent
25
2.9
Water absorption of natural and glass fiber composites (untreated)
26
2.10
Water absorption of natural fiber composites (treated)
26
2.11
Hypothetical reaction of silanol and the fiber
28
2.12
Proposed reaction mechanism for compatibilization
28
2.13
Stress-strain curves of typical kenaf filled coupled composites with 2%
2.14
of weight of coupling agent
29
Reaction steps in silane grafting of bio fiber surface
30
2.15A SEM micrographs of kenaf fiber surface in composites 100µm
(at 200x)
31
2.15B SEM micrographs of kenaf fiber surface in composites 10µm
(at 500x)
31
2.16a SEM micrographs of the tensile fracture surface of PP/kenaf (20%)
without MAPP
32
2.16b SEM micrographs of the tensile fracture surface of PP/kenaf (20%)
with MAPP
32
2.17a SEM micrograph of an untreated kenaf fiber
32
2.17b SEM micrograph of 3% NaOH treated kenaf fiber
32
x
3.1
Polypropylene Pellets
34
3.2
Flow chart of methodology
35
3.3
Kenaf fibers
36
3.4
Polypropylene-graft-maleic anhydride (MAPP)
37
3.5
Rotor mill machine
38
3.6
Dried kenaf fiber
39
3.7
Electronic Densimeter MD-300S
39
3.8
Scanning Electron Microscopy SEM EVO 50
41
3.9
Internal mixer HAAKE Rheomix OS
42
3.10
Hot Press machine G0-7014-A30
43
3.11
Universal Testing Machine UTM
44
3.12
Flexural Testing at three-point bending process
45
3.13
Standard test configuration of flexural test
46
3.14
Standard test configuration of Impact Test
46
3.15
Specimens mounted on the SEM stubs
48
4.1
Morphology of the kenaf fibers
50
4.2
Total weight loss of the kenaf short fiber in gram (g) of the drying process 52
4.3
Tensile Strength of the PP/Kenaf/MAPP composite
at different composition
4.4
54
Tensile Modulus of the PP/Kenaf/MAPP composite at different
composition
4.5
55
The SEM image of the fractured surface of pure PP at the 1000x
of magnification
4.6
56
The SEM image of the fractured surface of PP/kenaf composite with
10wt% of kenaf addition at the 1000x of magnification
4.7
The SEM image of the fractured surface of PP/kenaf composite with
20wt% of kenaf addition at the 1000x of magnification
4.8
57
57
The SEM image of the fractured surface of PP/kenaf composite with
30wt% of kenaf addition at the 1000x of magnification
xi
58
4.9
The SEM image of the fractured surface of PP/kenaf composite with
40wt% of kenaf addition at the 1000x of magnification
4.10
58
The SEM image of the fractured surface of PP/kenaf composite with
40wt% of kenaf addition and 3wt% of MAPP at the 1000x
of magnification
4.11
59
Flexural Strength of the PP/Kenaf/MAPP composite at different
composition
4.12
60
Flexural Modulus of the PP/Kenaf/MAPP composite at different
composition
4.13
61
The SEM image of the bending surface for pure PP at the 3000x
of magnification
4.14
62
The SEM image of the bending surface for PP/kenaf composite with
10wt% of kenaf fiber addition at the 1000x of magnification
4.15
The SEM image of the bending surface for PP/kenaf composite with
20wt% of kenaf fiber addition at the 1000x of magnification
4.16
66
The SEM image of the fractured surface for pure PP at the 1000x
of magnification
4.21
67
The SEM image of the fractured surface for PP/kenaf composite with
10wt% of kenaf fiber addition at the 1000x of magnification
4.22
68
The SEM image of the fractured surface for PP/kenaf composite with
20wt% of kenaf fiber addition at the 1000x of magnification
4.23
65
Impact Strength of the PP/Kenaf/MAPP composite at different
composition
4.20
64
The SEM image of the bending surface for PP/kenaf composite with
40wt% of kenaf fiber and 3wt% of MAPP at the 500x of magnification
4.19
64
The SEM image of the bending surface for PP/kenaf composite with
40wt% of kenaf fiber addition at the 1000x of magnification
4.18
63
The SEM image of the bending surface for PP/kenaf composite with
30wt% of kenaf fiber addition at the 1000x of magnification
4.17
63
68
The SEM image of the fractured surface for PP/kenaf composite with
30wt% of kenaf fiber addition at the 1000x of magnification
xii
69
4.24
The SEM image of the fractured surface for PP/kenaf composite with
40wt% of kenaf fiber addition at the 500x of magnification
4.25
69
The SEM image of the fractured surface for PP/kenaf composite with
40wt% of kenaf fiber addition and 3wt% of MAPP at the 350x
of magnification
4.26
70
Percentages of weight gain at the ambient temperature after 24 hours
immersion for different specimen composition
4.27
Percentages of thickness swelling at the ambient temperature after
24 hours immersion for different specimen composition
5.1
78
Tensile Properties and Morphological Behavior (1000 X Magnification)
of the pure PP and PP/Kenaf composites
5.3
82
Flexural Properties and Morphological Behavior (1000 X Magnification)
of the pure PP and PP/Kenaf/MAPP composites
5.6
86
Impact Strength and Morphological Behavior (1000 X Magnification)
of the pure PP and PP/Kenaf/MAPP composites
5.8
85
Flexural Properties and Morphological Behavior (1000 X Magnification)
of the PP/Kenaf/MAPP composites
5.7
81
SEM Fractured Surface for PP/Kenaf reinforced composite with
40wt% of kenaf fiber
5.5
79
Tensile Properties and Morphological Behavior (1000 X Magnification)
of the PP/Kenaf/MAPP composites
5.4
74
SEM morphology of the PP/Kenaf reinforced composite with
the introduction of 3wt% of MAPP
5.2
72
88
Impact Strength and Morphological Behavior (1000 X Magnification)
of the PP/Kenaf/MAPP composites
xiii
89
LIST OF ABBREVIATIONS, SYMBOLS, SPECIALIZED
NOMENCLATURE
200x
-
200 times magnification
%
-
Percent
0
-
Degrees Celsius
Ρ
-
Density
σ/ρ
-
Tensile Strength per unit mass (specific strength)
E/ρ
-
Tensile Modulus per unit mass (specific modulus)
-OH
-
Hydroxyl
AMPTES
-
3-aminopropyl-triethoxysilane
APS
-
3-aminopropyl-triethoxysilane
ASTM
-
American Society for Testing and Materials
CCC
-
Carbon-Carbon Composite
CMC
-
Ceramic-Matrix Composite
EcL
-
Longitudinal Young Modulus of Composite
EcT
-
Transverse Young Modulus of Composite
eg.
-
Example
et al.
-
and others
etc.
-
Et cetera
FRP
-
Fiber-reinforced plastics
g/cm3
-
Gram per Centimeter Cube
GPa
-
Giga Pascal
i.e.,
-
That is
J
-
Joule
Kw
-
Kilowatt
(M)
-
Malaysia
MAPP
-
Maleic-Anhydride Grafted Polypropylene
MAPP
-
Polypropylene-graft-maleic anhydride
C
xiv
min
-
Minutes
mm
-
Milimeter
mm/min
-
Milimeter per minute
µm
-
Micrometer
MMC
-
Metal-Matrix Composite
MPa
-
Mega Pascal
N
-
Newton
NF
-
Natural Fiber
N/mm2
-
Newton millimeter square
NaOH
-
Sodium Hydroxide
OH
-
Hydroxyl
PE
-
Polyethylene
PLLA
-
Poly-L-lactic acid
PMC
-
Polymer Matrix Composite
PP
-
Polypropylene
PP/kenaf
-
Kenaf Fiber Reinforced Polypropylene Composite
PS
-
Polystyrene
RoM
-
Rules of Mixtures
rpm
-
Revolution per minute
SEM
-
Scanning Electron Microscope
UTM
-
Universal Testing Machine
UV
-
ultraviolet
wt%
-
Percent of weight fraction
xv
CHAPTER 1
INTRODUCTION
1.1
Background of Study
Recently, the used of fiber-reinforced plastics (FRP) composite becomes famous in
manufacturing industry. The primary advantages of using fiber as filler/reinforcement in
plastics are low densities, non abrasive high filling levels possible resulting in high
stiffness properties, high specific properties, easily recyclable, the fibers will not
fractured when processing over sharp curvatures, biodegradable, low energy
consumption and low cost of production (Kahraman et al., 2005). Throughout its
performance, FRP composites play a vital role in consumer needs or products that
exhibits high level of mechanical properties. The main purpose of using the FRP
composites is to improve the mechanical properties of existing polymeric materials. The
FRP composite can be defined as a material consists of polymer such as Polypropylene
(PP), Polyethylene (PE), Polystyrene (PS) and etc. as matrix and fiber as reinforcement.
Each matrix or reinforcement type can be distinct because of its physical or mechanical
properties, materials form and chemical composition.
Products in a monolithic material are widely used in a daily life such as bottle, food
packaging, vehicles, piping, electronic and etc. These examples of plastics product were
specifically produced by using PP, PE, and PS. However, the manipulation of
monolithic polymer materials as daily life products are not exhibits the high
performances especially in vehicles and electronics application. High impact resistance
is necessary for vehicles and high melting temperature is needed for electronic part
1
(Paul et al., 2008). Melting temperature for PP which is 175ºC has proved that it is not
suitable to be used in electronic and engine vehicles which commonly operated at
higher temperature of service (Kalpakjian and Schmid, 2006; Callister, 2003).
Therefore, the introduction to the fabrication of composites which utilizes the
advantages of fiber reinforcement should capable to improve the performances compare
to monolithic polymeric material, especially in highly demanding application like
automotives and electronics application.
There are two types of fiber commonly used in composites which are natural fiber and
synthetic fiber. Both types of fiber got higher potential to be used as a reinforcement
agent in composite materials. For low cost of production and widely availability of
fiber, natural fiber had been chosen for this study. Natural fiber had played important
roles in enhancing the composites performance. Kenaf, Jute, and Hemp namely as
natural fiber were widely used as reinforcement for composites. In addition, the
performance of the natural fiber, especially kenaf has proved by researchers previously
as the multipurpose used materials because of kenaf plant itself include the stalks (bast
and core), leaves and seeds to be produced as useful material in manufacturing industry.
Beyond the new uses for kenaf including its utilization in building material, absorbents,
household, and vehicles, the commercial success of kenaf has great potential economic
and environmental benefits in replacement or reduced use of fiberglass in industrial
products and the increased used of recycled plastics (Webber et al., 2002). However,
there were also disadvantages of using natural fiber in thermoplastics through its lignocellulosic properties which are the high moisture absorption of the fibers and the low
processing temperature permissible during the fabrication process (Sanadi et al., 1995).
In order to increase the performances and properties of fabricated composites, the
compatibilizer should be introduced. Various types of chemical reagents have been used
in previous study by researchers such as silane, Maleic-Anhydride Grafted
Polypropylene (MAPP), alkoxysilane and etc. Besides the using of Silane, Maleated
coupling agents are widely used as its main function to enhance the interactions
2
between the matrix and fiber and to strengthen composites containing fillers and fiber
reinforcement (Keener et al., 2004). Therefore, the introduction of MAPP as
compatibilizer has been employed through the study in order to improve the mechanical
properties of the fabricated composites.
1.2
Problem Statements
It is important and possible to produce a new types of material that exhibit the
economically and environmentally benefits for the applications in automotive, building,
furniture and packaging industries. By combining the different resources, it is possible
to blend, mix or process the natural fiber with other elements such as glass, plastics and
synthetics material to produces new classes of materials (Sanadi et al., 1990).
Biodegradable or environmentally acceptable materials have attained increasing interest
in few decades to the researchers and manufactures due to the environmental pressure
derived from the consumption of petroleum-based materials, difficulties in degrade in a
landfill and composting environments (Liu et al., 2006; Huda et al., 2007). Thus, the
introduction of natural fiber such as kenaf, hemp, ramie and flex has attractively
influenced the production of biodegradable materials lately, especially in manufacturing
industry (Bledski et al., 2002).
Natural fiber like kenaf can be used as replacement to the conventional fiber. Global
environmental issues have led to a renewed interest in bio-based materials like fiber
glass or carbon fiber; which the focus on renewable raw materials can be biodegradable
or recyclable at reasonable cost (Hong et al., 2007; Zampaloni et al., 2007). The
problem faced by the researchers and manufacturers is to find the good natural fiber for
polymer composite application equipped with the most promising and outstanding
mechanical and physical properties. The uses of natural plant fibers as a reinforcement
materials to replace synthetic fibers is receiving great attention, due to the advantages of
renewability, low density and high specific strength (Ochi, 2008). These fiber
3
outstanding properties such as high specific strength in stiffness, impact resistance,
flexibility, and modulus make them an attractive alternative over the traditional
materials (Sgriccia et al., 2008). Specifically, the good properties of kenaf fiber include
good specific strengths and modulus, economical viability, low density and low weight
has make them as a reinforcement of choice by industry.
The low processing temperature permissible to the ligno-cellulosic fiber in
thermoplastics is limited due to fiber degradation at higher processing temperatures
(Sanadi et al., 1995). It is important to ensure that the fabrication are employed in the
controlled temperature processing, because the degradation of the kenaf fiber will lead
to the failure or poor performance to the properties of the fabricated composite.
Therefore, the chosen suitable processing temperature is important consideration
accordance to the fabrication of PP/kenaf composites.
1.3
Objectives
The purpose of this study is:
a) To study the effects of different fibers loading of kenaf (wt %) to the mechanical
properties of the fiber reinforced polypropylene composite;
b) To study the effects of proposed compatibilizer on the fabrication of PP/kenaf
fiber and compare its effect to the properties enhancement of the fabricated
composites.
4
1.4
i).
Hypotheses
The different filler loading or proportion of kenaf short fiber used for this study
will affect the mechanical properties of the composite. It is expected that, by
increasing the proportion of filler loading, mechanical properties of the
fabricated composite must be also increased correspondingly in accordance with
the rules of mixture theory.
ii).
Introduction of compatibilizer in this study will increased the mechanical
properties of the fabricated composites. The good interfacial adhesion formed
between the surface interaction of kenaf fiber and PP matrix is expected to
improve the properties of composites materials.
1.5
Scope of study
The study was started by preparing and characterizing the kenaf fiber as raw materials
to be used as reinforcement material in the fabrication of PP/kenaf composite. The
materials used that related in this study are polypropylene (PP) pellets and kenaf short
fibers. The kenaf short fibers were prepared by using the rotor mill to get the various
size of fiber length. The size and density of the fiber reinforced were determined by
using Scanning Electron Microscope (SEM) model EVO 5 and Electronic Densimeter
model MD300-S, respectively. However, the kenaf properties are difficult to measure,
thus no preliminary study on the kenaf properties was carried out during this research
(Sanadi et al., 1995).
Next stage of process involves the drying study of kenaf fiber. Kenaf fibers will be
dried in the drying oven for seven hours period of time and the weight losses of fibers
were weighed for every hour. The effects of fiber loading for kenaf short fiber on
polypropylene composites were investigates by varying the weight percentage (wt%)
for both materials. There are five fraction of fiber loading will be employed in this study
5