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
ABSTRACT
ABSTRAK
DEDICATION
ACKNOWLEDGEMENT
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 10
2.3.1 Polypropylene (PP) as Matrix Material 11 2.4 Reinforcement 12
2.4.1 Natural fiber 13
2.4.1.1 Kenaf fiber 15
2.5 Processing of composites 18
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 3.2.3 Coupling agents 37 3.3 Raw materials preparation 38
3.3.1 Crushing 38
3.3.2 Kenaf fiber drying process 38 3.4 Characterization of kenaf short fiber 39 3.4.1 Density measurement 39 3.4.2 Water absorption 40 3.4.3 Drying profile study 40 3.4.4 Microscopy study 40 3.5 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 3.6 Mechanical testing 44
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 Fiber size 49
4.2.2 Density 50
4.2.3 Drying study 51
4.3 Observation of Sample Preparation Process 52
4.4 Critical Property Analysis - Tensile Test 53 4.4.1 Fracture Surface Morphology of Tensile Specimen 55
4.5 Flexural Test 59
4.5.1 Bending Surface Morphology of Flexural Specimen 61 4.6 Impact Test 65
4.6.1 Fracture Surface Morphology of Impact Specimen 67
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
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
LIST OF TABLES
2.1 Comparison of Thermoplastics and Thermosets polymer 12 2.2 Comparison of Properties of Kenaf-Filled PP with typical
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 54 4.4 Flexural properties of pure PP and PP/kenaf fiber composite with
the absence and presence of MAPP 60 4.5 Impact properties of pure PP and PP/kenaf fiber composite with
the absence and presence of MAPP 66 4.6 Weight deflection and Percentage of weight gain of specimens
at the different composition of kenaf fiber addition 71 4.7 Thickness deflection and Percentage of thickness swelling of specimens
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%
of weight of coupling agent 29 2.14 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
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 54 4.4 Tensile Modulus of the PP/Kenaf/MAPP composite at different
composition 55
4.5 The SEM image of the fractured surface of pure PP at the 1000x
of magnification 56
4.6 The SEM image of the fractured surface of PP/kenaf composite with
10wt% of kenaf addition at the 1000x of magnification 57 4.7 The SEM image of the fractured surface of PP/kenaf composite with
20wt% of kenaf addition at the 1000x of magnification 57 4.8 The SEM image of the fractured surface of PP/kenaf composite with
4.9 The SEM image of the fractured surface of PP/kenaf composite with
40wt% of kenaf addition at the 1000x of magnification 58 4.10 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 59
4.11 Flexural Strength of the PP/Kenaf/MAPP composite at different
composition 60
4.12 Flexural Modulus of the PP/Kenaf/MAPP composite at different
composition 61
4.13 The SEM image of the bending surface for pure PP at the 3000x
of magnification 62
4.14 The SEM image of the bending surface for PP/kenaf composite with
10wt% of kenaf fiber addition at the 1000x of magnification 63 4.15 The SEM image of the bending surface for PP/kenaf composite with
20wt% of kenaf fiber addition at the 1000x of magnification 63 4.16 The SEM image of the bending surface for PP/kenaf composite with
30wt% of kenaf fiber addition at the 1000x of magnification 64 4.17 The SEM image of the bending surface for PP/kenaf composite with
40wt% of kenaf fiber addition at the 1000x of magnification 64 4.18 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 65 4.19 Impact Strength of the PP/Kenaf/MAPP composite at different
composition 66
4.20 The SEM image of the fractured surface for pure PP at the 1000x
of magnification 67
4.21 The SEM image of the fractured surface for PP/kenaf composite with
10wt% of kenaf fiber addition at the 1000x of magnification 68 4.22 The SEM image of the fractured surface for PP/kenaf composite with
20wt% of kenaf fiber addition at the 1000x of magnification 68 4.23 The SEM image of the fractured surface for PP/kenaf composite with
4.24 The SEM image of the fractured surface for PP/kenaf composite with
40wt% of kenaf fiber addition at the 500x of magnification 69 4.25 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 70
4.26 Percentages of weight gain at the ambient temperature after 24 hours
immersion for different specimen composition 72 4.27 Percentages of thickness swelling at the ambient temperature after
24 hours immersion for different specimen composition 74
5.1 SEM morphology of the PP/Kenaf reinforced composite with
the introduction of 3wt% of MAPP 78 5.2 Tensile Properties and Morphological Behavior (1000 X Magnification)
of the pure PP and PP/Kenaf composites 79 5.3 Tensile Properties and Morphological Behavior (1000 X Magnification)
of the PP/Kenaf/MAPP composites 81 5.4 SEM Fractured Surface for PP/Kenaf reinforced composite with
40wt% of kenaf fiber 82 5.5 Flexural Properties and Morphological Behavior (1000 X Magnification)
of the pure PP and PP/Kenaf/MAPP composites 85 5.6 Flexural Properties and Morphological Behavior (1000 X Magnification)
of the PP/Kenaf/MAPP composites 86 5.7 Impact Strength and Morphological Behavior (1000 X Magnification)
of the pure PP and PP/Kenaf/MAPP composites 88 5.8 Impact Strength and Morphological Behavior (1000 X Magnification)
LIST OF ABBREVIATIONS, SYMBOLS, SPECIALIZED
NOMENCLATURE
200x - 200 times magnification % - Percent
0C - 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
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
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.
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(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 ligno-cellulosic properties which are the high moisture absorption of the fibers and the low processing temperature permissible during the fabrication process (Sanadi et al., 1995).
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).
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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;
1.4 Hypotheses
i). 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).
