universiti putra malaysiapsasir.upm.edu.my/51546/1/fk 2009 116rr.pdfuniversiti putra malaysia nor...

UNIVERSITI PUTRA MALAYSIA

NOR HASNI BINTI ZAHARI

FK 2009 116

DEVELOPMENT OF CARBON FIBER-REINFORCED POLYPROPYLENE COMPOSITE FOR CAR BUMPERS

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DEVELOPMENT OF CARBON FIBER-REINFORCED POLYPROPYLENE

COMPOSITE FOR CAR BUMPERS

By


Thesis Submitted to

the School of Graduate Studies, Universiti Putra Malaysia

in Partial Fulfilment of the Requirements for the Degree of Master of Science

May 2009

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Thanks to my beloved husband, mom, auntie, sisters and brother for their support during the long preparation of this thesis.

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Abstract of thesis presented to the Senate of Universiti Putra Malaysia in fulfilment

of the requirement for the degree of Master of Science in Chemical Engineering.

DEVELOPMENT OF CARBON FIBER-REINFORCED

POLYPROPYLENE COMPOSITE FOR CAR BUMPERS

By


May 2009

Chairman : Professor Madya Robiah Bt. Yunus, PhD

Faculty : Engineering

Carbon fiber reinforced composites (CFRC) are very strong and extremely lighter

than steel. Their toughness provides excellent abrasion and tear resistance. The usage

of the CFRC in automotive industries is widely explored due to the new requirements

related to energy conservation, safety and antipollution. In this study, discontinuous

carbon fiber reinforced polypropylene composite was selected due its characteristics

such as light-weight, corrosion resistance, low to moderate cost, thermal stability and

ease of fabrication.

Polypropylene (PP) was chosen as the matrix because it is available in large

quantities and not very sensitive to chemical stress cracking. PP also has a

combination of high elongation and tensile strength. Carbon fibers are widely used in

polymer–matrix composites owing to their good mechanical, thermal and electrical

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properties. Cheap discontinuous carbon fiber or short fiber is the low quality carbon

fiber which cannot be used in aircraft and aerospace industry which requires high

quality continuous-fiber laminates as primary structures. The composite was

developed to fill the mechanical property gap between the discontinuous-fiber

composites and the un-reinforced polymers used in non-load-bearing applications.

The objectives of this work are to develop carbon fiber polypropylene composite

under various process conditions, and to investigate the mechanical and thermal

properties of carbon fiber polypropylene composite. In this study, two different

types of polypropylene composites were produced by mixing and compressing the

mixtures using hot press. In the first stage, the mixture was prepared by mixing

polypropylene with chopped carbon fiber and carbon fiber percentage (wt%) was

varied. The composites were evaluated for mechanical properties. Mixing time,

mixing temperature and rotor speed were varied to determine the best conditions.

Among the mechanical testing and analysis investigated were tensile test, impact test,

bending test and density test. Whilst the, the Scanning Electron Microscopy (SEM)

was employed to study the morphology of the composites and Dynamic mechanical

analysis (DMA) and Thermal gravimetric analysis (TGA) were used to determine the

thermal properties

The highest tensile strength was obtained for polypropylene with melt flow index 60

(MFI 60) composites reinforced with 10 wt% carbon fiber. The composite also

showed the best tensile and flexural properties. TGA analysis of composite with 10

wt% carbon fiber content revealed excellent thermal stability compared to the plain

polypropylene. The performance of the selected composite was comparable to a local

commercial car bumper.

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Abstrak thesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai

memenuhi sebahagian keperluan untuk Ijazah Master Sains dalam Kejuruteraan

Kimia.

PEMBANGUNAN KOMPOSIT GENTIAN KARBON-

MEMPERKUAT POLIPROPILENA UNTUK BAMPER KERETA

Oleh


Mei 2009

Pengerusi : Profesor Madya Robiah Bt. Yunus, PhD

Fakulti : Kejuruteraan

Komposit diperkuat gentian karbon (CFRC) adalah sangat kuat dan jauh lebih ringan

berbanding aloi. Sifatnya yang tahan lasak menjadikan ia tahan hakisan dan

mempunyai rintangan carikkan. Penggunaan CFRC di dalam industri automotif telah

dipraktikkan secara meluas berdasarkan kepada kehendak terkini yang

mengutamakan penjimatan tenaga, keselamatan dan antipencemaran. Dalam kajian

ini, komposit gentian karbon tidak bersambung perkuat polipropilena telah dipilih

berdasarkan ciri-ciri seperti ringan, tahan karat, kos yang rendah ke sederhana,

kestabilan terma dan mudah dibentuk.

Polipropilena (PP) telah dipilih sebagai matrik kerana ia boleh diperolehi dalam

kuantiti yang banyak dan tidak terlalu sensitif terhadap retakan tekanan kimia. PP

juga mempunyai kombinasi sifat yang tinggi rintangan dan kekuatan tegangan.

Gentian karbon telah digunakan secara meluas dalam komposit polimer-matrik

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kerana sifat-sifat mekanikal, terma dan elektriknya. Gentian karbon tidak

bersambung atau gentian pendek yang murah adalah gentian karbon yang berkualiti

rendah di mana ia tidak boleh digunakan dalam industri pesawat udara dan angkasa

yang memerlukan penggunaan lapisan gentian bersambung berkualiti tinggi sebagai

struktur asas. Komposit ini dibangunkan untuk memenuhi jurang sifat mekanikal di

antara gentian karbon tidak bersambung dan polimer yang tidak bertetulang yang

digunakan untuk aplikasi galas tidak berbeban.

Objektif bagi kajian ini adalah untuk membina komposit gentian karbon

polipropilena di bawah pelbagai kondisi proses, dan untuk mengkaji sifat mekanikal

dan terma bagi komposit gentian karbon prolipropilena. Dalam kajian ini, dua jenis

polipropilena yang berbeza dihasilkan melalui pencampuran dan himpitan bahan

campuran itu dengan menggunakan penekan panas. Campuran dihasilkan dengan

mencampurkan polipropilena bersama gentian karbon yang telah dipotong dan

peratusan (wt%) gentian karbon ini dipelbagaikan. Komposit ini dinilai melalui sifat-

sifat mekanikalnya. Masa pencampuran, kelajuan rotor, suhu dan masa pengacuan

dipelbagaikan untuk mendapatkan kondisi terbaik.

Antara ujian dan analisa secara mekanikal diperoleh melalui ujian kekuatan

tegangan, kekuatan hentaman, kekuatan lenturan dan ujian ketumpatan. Analisis

dinamik mekanik (DMA) dan analisis gravitian terma (TGA) dijalankan untuk

mengenalpasti sifat-sifat terma. Scanning Electron Microscopy (SEM) digunakan

untuk mengkaji kesan morfologi.

Kekuatan tegangan yang tertinggi bagi komposit gentian karbon perkuat

polipropilena diperoleh adalah pada 10 wt% gentian karbon perkuat polipropilena

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dengan MFI 60. Komposit tersebut menunjukkan keputusan sifat-sifat kekuatan

tegangan dan lenturan yang lebih baik. Analisis TGA bagi 10 wt% gentian karbon

memberi menunjukkan kestabilan terma yang lebih baik berbanding polipropilena

asli. Prestasi komposit terpilih telah dibandingkan dengan sebuah bamper komersial

tempatan.

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ACKNOWLEDGEMENTS

First and foremost, I would like to thank my Advisor and Chairman of the

Supervisory Committee, Assoc. Prof. Dr. Robiah Yunus for her support and

encouragement throughout this study. My appreciation also goes to my supervisory

committee Dr. Mohamad Amran Mohd Salleh and Dr. Nor Azowa Ibrahim, for their

constant guidance and encouragement. Thank you for providing me with professional

training, advice and suggestion.

I am grateful to the staff, technicians and my colleagues in the Material Science and

Engineering Laboratory, Department of Chemical and Environmental Engineering,

Faculty of Engineering and Polymer Laboratory, Chemical Department, Faculty of

Science, Universiti Putra Malaysia. And last, but not least I would like to express my

gratitude to my dear husband, my beloved mother, my auntie, sisters and brother for

their continuous support during the completion of this thesis.

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I certify that the Examination Committee meet on 21st May 2009 to conduct the final

examination of Nor Hasni Binti Zahari on her Master of Science in Chemical

Engineering thesis entitled “Development of Carbon Fiber Reinforced

Polypropylene Composite for Car Bumper Application” in accordance with

Universiti Pertanian Malaysia (Higher Degree) Act 1980 and Universiti Pertanian

Malaysia (Higher Degree) Regulations 1981. The Committee recommends that the

candidate be awarded a relevant degree. Members of the Examination Committee are

as follows:

Fakhru’l-Razi Ahmadun, PhD

Professor

Faculty of Graduate Studies

Universiti Putra Malaysia

(Chairman)

Luqman Chuah Abdullah, PhD

Associate Professor



(Internal Examiner)

Suraya Abdul Rashid, PhD

Lecturer



(Internal Examiner)

Ahmad Fauzi Ismail, PhD

Professor



(External Examiner)

________________________

BUJANG KIM HUAT, PhD

Professor and Deputy Dean

School of Graduate Studies


Date: 24 December 2009

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This thesis submitted to the Senate of Universiti Putra Malaysia and was accepted as

fulfilment of the requirement for the degree of Master of Science in Chemical

Engineering. The members of the supervisory committee were as follow:

Robiah Yunus, PhD

Associate Professor

Faculty of Engineering


(Chairman)

Nor Azowa Ibrahim, PhD

Lecturer

Faculty of Science


(Member)

Mohamad Amran Mohd Salleh, PhD

Lecturer

Faculty of Engineering


(Member)

________________________________

HASANAH MOHD GHAZALI, PhD

Professor and Dean

School of Graduate Studies


Date: 14 January 2010

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DECLARATION

I hereby declare that the thesis is based on my original work except for quotations

and citations which have been duly acknowledged. I also declare that it has not been

previously or co currently submitted for any other degrees at UPM or other

institutions.

__________________________


Date:

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TABLE OF CONTENTS

DEDICATION ii

ABSTRACT iii

ABSTRAK v

ACKNOWLEDGEMENTS viii

APPROVAL ix

DECLARATION xi

LIST OF TABLES xiv

LIST OF FIGURES xv

LIST OF ABBREVIATIONS xviii

CHAPTER

1. INTRODUCTION

1.1 Background

1.2 Problem Statement

1.3 Objectives and Scope of Research Work

1.4 Thesis Layout

1

1

2

5

6

2. LITERATURE REVIEW

2.1 Carbon Fiber

2.1.1 PAN Carbon Fiber

2.1.2 Pitch Carbon Fiber

2.2 Glass Fiber

2.3 Composites

2.3.1 Polymer Composites

2.3.2 Composite Manufacturing

2.4 Resin System

2.4.1 Thermoset Polymer

2.4.2 Thermoplastic Polymer

2.5 Polyurethane

2.6 Polypropylene

2.7 Thermoplastic Composites

2.7.1 Long Fiber Reinforced Thermoplastic (LFT) Composites

2.7.2 Short Fiber Reinforced Polymer (SFRP) Composites

2.7.3 Carbon Fiber Reinforced Polypropylene Composite

(CFPP)

2.8 Polymer Properties: Molecular Weight and Flow Rate

2.8.1 Dynamic Mechanical Properties of Polymer

2.9 Bumper System and Components

2.10 Comparison between Metal and Composites

2.11 Summary

7

7

8

10

11

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47

3. METHODOLOGY

3.1 Carbon Fiber Reinforced Polyurethane (CFPU)

3.1.1 Material Preparation

3.1.2 Preparation of CFPU composites by internal mixer

3.1.3 Results and Discussions of CFPU composites (by

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Internal Mixer)

3.1.4 Preparation of CFPU Composites by Open Cast

3.2 Carbon Fiber Reinforced Polypropylene (CFPP)

3.2.1 Preparation of CF Reinforced PP Composites (CFPP)

3.3 Mechanical Testing

3.3.1 Tensile Test

3.3.2 Flexural Test

3.3.3 Izod Impact Test

3.3.4 Hardness Measurement

3.4 Characterization of CFPP Composites

3.4.1 Density Measurement

3.4.2 Scanning Electron Microscope (SEM) Analysis

3.4.3 Thermal Gravimetric Analysis (TGA)

3.4.4 Dynamic Mechanical Analysis (DMA)

3.5 Bumper Analysis

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4. RESULTS AND DISCUSSIONS

4.1 Introduction

4.2 Carbon Fiber Reinforced Polypropylene (CFPP)

4.2.1 Effect of Mixing Temperature for CFPP MFI 60

4.2.2 Effect of Rotor Speed for CFPP MFI 7

4.3 Density Test

4.4 Tensile Test

4.4.1 Tensile Strength

4.4.2 Tensile Modulus

4.5 Flexural Properties

4.5.1 Flexural Strength

4.5.2 Flexural Modulus

4.6 Impact Properties

4.7 Hardness Measurement

4.8 Thermal Gravimetric Analysis (TGA)

4.9 Dynamic Mechanical Analysis (DMA)

4.9.1 Storage Modulus (E’)

4.9.2 Loss Modulus (E”)

4.9.3 Tan Delta (Tan δ)

4.10 Scanning Electron Microscope (SEM)

4.11 Comparison of CFPP Composite and Commercial Plastic

Bumper Fascia

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106

5. CONCLUSIONS AND RECOMMENDATIONS

5.1 Introduction

5.2 Conclusions

5.3 Recommendations

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110

REFERENCES 111

APPENDIX 118

BIODATA OF STUDENT 120

LISTS OF PUBLICATION 121

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LIST OF TABLES

Table Page

2.1 Summary of the Diverse Method of Processing Composite Product 18

2.2 Advantages and Disadvantages of Polymer and Steel Systems 45

2.3

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

3.10

Distribution of Materials in a Typical Vehicle

Mechanical and Physical Properties of CF, PU and hardener

Parameters and setting on CFPU study

Parameters and Setting for CFPU Mixing Process

Parameters and setting for CFPU Molding Process

Mechanical Properties of Polypropylene with melt flow rate (MFI)

60 and 7

Mechanical and Physical Properties of CF and PP

Carbon Fibers and Polypropylene Percentage and Weight

Parameters and Conditions for Compounding CFPP MFI 60

Parameters and Conditions for Compounding CFPP MFI 7

Parameters and Setting for Compression Molding of CFPP MFI 60

and CFPP MFI 7

46

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49

49

50

57

57

59

60

60

61

4.1 Storage Modulus and % Improvement at 60oC for CFPP MFI 60 92

4.2 Storage Modulus and % Improvement at 60oC for CFPP MFI 92

4.3 Comparison of Composites and Commercial Plastic Fascia

107

4.4 Percentage of Improvement of CFPP MFI 60 at 10 wt% CF

Compared to Commercial Plastic Bumper Fascia

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LIST OF FIGURES

Figure Page

2.1 Carbon Fiber Reel 8

2.2 Flow Diagram for Manufacturing Process of Carbon Fiber

(PAN type)

9

2.3 Alignment of Mesophase Pitch into a Pitch Filament 10

2.4 Glass Fiber (a) Glass Strand (b) Glass Fiber Perform for a Boat

Deck

11

2.5 Mechanical Properties of Different Material 13

2.6 Polymer Structure (a) Themoset Polymer (b) Thermoplastic

Polymer

19

2.7 Morphology of Elastomer Polymer 21

2.8 General Reaction in the Production of Polyurethane 24

2.9 Molecular structure of MOCA 25

2.10 Polypropylene Molecule Chain (a) Isotactic; (b) Sydiotactic

where R is CH3

26

2.11 Build-up of Stress on a Fiber in a Matrix 33

2.12 Bumper Systems in Common Use 40

2.13

3.1

GMT Bumper Beam for BMW

Tensile Strength of CFPU Composites

43

51

3.2

3.3

3.4

3.5

3.6

Tensile Modulus of CFPU Composites

Method of Producing Polyurethane

Design of Equipment for CFPU Production

Carbon Fiber Yarn

Chopped Carbon Fiber

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3.7

3.8

3.9

3.10

3.11

3.12

3.13

Experimental Steps for The Composite Preparation

Internal Mixer (Thermo Haake Rheomix)

HSINCHU Hot Press Machine

Instron Universal Testing Machine 4302

Izod Impact Tester

Notch Cutter

Local Bumper

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4.1 Tensile Strength for Various Carbon Fiber Loading at Different

Mixing Temperature

70

4.2 Tensile Strength for 5wt% CF Reinforced PP with MFI 7 at

Different Rotor Speeds

72

4.3 Tensile Modulus for 5wt% CF Reinforced PP with MFI 7 at

Different Rotor Speeds

72

4.4 Density Measurement for CFPP MFI 60 and CFPP MFI 7 at

Different Fiber Loading

73

4.5 Tensile Strength (MPa) for CFPP Carbon Fiber (wt%) 74

4.6 Tensile Modulus (MPa) for CFPP Carbon Fiber (wt%) 78

4.7 Flexural Strength (MPa) versus Carbon Fiber (wt%) 80

4.8 Flexural Modulus (MPa) versus Carbon Fiber (wt%) 81

4.9 Impact Strength for Various CF Loading 83

4.10 Hardness Property at Various CF Loading 84

4.11 TGA of PP and CFPP at 10wt% fiber 86

4.12 Storage Modulus for PP MFI 60 and CFPP MFI 60 Composites 89

4.13 Storage Modulus for PP MFI 7 and CFPP MFI 7 Composites 91

4.14 Loss Modulus for PP MFI 60 and CFPP MFI 60 Composites 94

4.15 Loss Modulus for PP MFI 7 and CFPP MFI 7 Composites 95

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4.16 Tan Delta for PP MFI 60 and CFPP MFI 60 Composites 97

4.17 Tan Delta for PP MFI 7 and CFPP MFI 7 Composites 98

4.18 SEM micrograph of tensile fracture surface of 5 wt% CF

reinforced PP MFI 60 composite

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101



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LIST OF SYMBOLS AND ABBREVIATIONS

ASTM American Society for Testing Materials

BIW Body-In-White

CF Carbon Fiber

CFPP Carbon Fiber Reinforced Polypropylene

CFPU Carbon Fiber Reinforced Polyurethane

CR Controlled Rheology

CTE Coefficients of Thermal Expansion

DMA Dynamic Mechanical Analysis

E’ Storage Modulus or Elastic Modulus

E” Loss Modulus or Viscous Modulus

FRP Fiber Reinforced Plastic

GFRP Glass Fiber Reinforced Plastic

GMT Glass Mat Thermoplastic

IC Isocyanates

Lc Critical Fiber Length

LFT Long Fiber Thermoplastic

MFI Melt Flow Index

Mn Number Average Molecular Weight

Mn/Mw Molecular Weight Distribution or Dispersity Index

MOCA 4,4'-methylene-bis(2-chloroaniline)

mph Miles Per Hour

MFR Melt Flow Rate

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Mw Weight Average Molecular Weight

NVH Noise, Vibration, and Harshness

OEM Original Engineering Manufacturing

PAN Polyacrylonitrile

PP Polypropylene

PU Polyurethane

r Fiber Radius

RH Rockwell Hardness

RIM Reaction Injection Molding

SEM Scanning Electron Microscope

SFRP Short Fiber Reinforced Polypropylene

SFRT Short Fiber Reinforced Thermoplastic

SMC Sheet Moulding Compound

t Interfacial Shear Strength

Tan δ Tangen delta

Tg Glass Transition

TGA Thermal Gravimetric Analysis

Tm Melting Point (oC)

UPM Universiti Putra Malaysia

wt Weight

σmax Tensile Stress Acting on the Fiber

µm Micro Meter

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CHAPTER ONE

INTRODUCTION

1.1 Background

Glass fibers are the most common reinforcing fibers for polymeric (plastic) matrix

composites. The advantages of this fiber are low cost, high tensile strength, high

chemical resistance and excellent insulating properties. Thus it has always been chosen

as a filler in a composite production. However, this type of fibers has a low tensile

modulus, relatively high specific gravity (among commercial fibers), sensitive to

abrasion and low fatigue resistance (Mallick, 1993).

In the early 1960s, carbon fiber was invented at the Royal Aircraft Establishment,

Farnborough, Hampshire (England) (Wikipedia, 2006). Carbon fibers are fibrous

material with carbon content of more than 90%. They are transformed from organic

matter by 1000-1500oC heat treatment, which is the substance with imperfect graphite

crystalline structure arranged along the fiber axis (Donnet et al. 1998). They are

characterized by very high stiffness and low density. Some carbon fibers have a

stiffness that are ten times higher and densities that are one half that of glass fibers.

According to Adam (1997), the application of carbon fiber is due to the high energy

absorption ability. Thus the material can contribute to an improved crash management

and therefore to an improved passive safety of a passenger car.

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Carbon fiber composite can be designed as a component of energy absorbers to absorb a

portion of the kinetic energy from a vehicle collision. Energy absorbers are very

effective in a low speed impact, where the bumper springs back to its original position.

Energy absorber types include foam, honeycomb and mechanical devices. All foam and

honeycomb absorbers are made from polypropylene, polyurethane or low-density

polyethylene. Mechanical absorbers are metallic and resemble shock absorbers.

However, mechanical absorbers have several times the weight of foam or honeycomb

absorber and receive very limited usage. In some bumper systems, the reinforcing beam

itself is designed to absorb energy and separate energy absorbers are not required.

1.2 Problem Statement

A bumper is a shield made of steel, aluminum, rubber or plastic that is mounted on the

front and rear of a passenger car. Traditionally, metal alloys were used in manufacturing

automobile exteriors. Nowadays, the car bumper generally consists of a plastic cover

and, underneath, reinforcement is made of steel, aluminum, fiberglass composite or

plastic and includes mechanisms that compress to absorb crash energy. Usually, bumper

system consists of built-in fascia, beam and energy absorbers.

There are several factors that an engineer must consider when selecting a bumper

system. The most important factor is the ability of the bumper system to absorb enough

energy to meet the Original Engineering Manufacturing (OEM) internal bumper

standard. Another important factor is the bumper’s ability to absorb energy and stay

intact at high-speed impacts (AISI, 2003). Five miles per hour (5 mph) is a benchmark

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that engineers must comply when designing the bumper system. It is an impact speed at

which bumpers could prevent damage in barrier test (Cheon, et al. 1995). The 5 mph

crash test can be used to assess bumper performance, including front-into-flat-barrier

test, rear-into-flat-barrier test, front-into-angle-barrier test and rear-into-pole test. The

least demanding impacts are front and rear-into-flat-barrier because the energy of the

crash is spread across the whole width of the vehicle.

Automotive bumper system plays a very important role not only in absorbing impact

energy (original purpose of safety) but also in a styling stand point. In recent years, a

great deal of attention within the automotive industry has been focused upon lightweight

and safety issues. The bumper system equipped with thermoplastic and energy absorbing

element is a new trend in the market. While experimental test is rather costly and time

consuming, finite element analysis helps engineers to study design concept at an early

design stage when prototypes are not available (Lee and Jang, 1993).

Automobile design engineers face many constrictions when designing with metal, such

as corrosion and dents. Low-cost, single-unit production of large automobile sections,

such as a front grille, is nearly impossible when using metal. Plastic offers auto

engineers a variety of practical, costs-effective alternatives, as well as tremendous

advantages over traditional automobile production materials. By using plastics,

manufacturers have the possibility of adopting modular assembly practices, lowering

production costs, improving energy management, achieving better dent resistance, and

using advanced styling techniques for sleeker, aerodynamic exteriors. However, plastic

outer cover does not promise good protection if it performs alone (Mallick, 1993).

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With current technology, many manufacturers are using composite instead of plastic

alone to fabricate the automotive parts including the bumper. Fuel efficiency and

emission gas regulations are the main causes for reducing the weight of passenger cars

by using composite structures (Hosseinzadeh et al. 2005). In the last few years, more

intense effort have been spent on the application of fiber reinforced plastics. While glass

fiber reinforced plastics (GFRP) are used in several vehicle components, the carbon

fibers as reinforcing material are of relative low significance for the lightweight

construction in motor vehicles (Adam, 1997).

Short fiber reinforced composites have enormous potential for automotive application

(Adam, 1997). To achieve these advantages, many researchers focus on the

discontinuous carbon fiber reinforced polypropylene composite where the material is

expected to have a better property and has a potential to reduce the weight of a car and

fuel consumption. The use of a short-carbon-fiber or discontinuous carbon fiber

reinforced polypropylene (SCF/PP) composite has been investigated by Rezaei et.al

(2007) for car bonnet application. They found that the SCF/PP composite is a good

option for replacing steel in car bonnet and can achieve the standards of car bonnet with

remarkable lower weight and higher mechanical properties. However, this study focuses

on the use of discontinuous carbon fiber reinforced polypropylene composite for the

application of car bumper which requires different specifications.

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1.3 Objectives and Scope of Research Work

The objectives of this research are:

(a) To develop carbon fiber polypropylene composites under various process

conditions.

(b) To investigate the mechanical and thermal properties of carbon fiber

polypropylene composites.

Based on the first objective, the scope of work stated with preliminary investigation on

the existing bumper system of a passenger car in order to understand the material

properties. This was undertaken so that improvement on the material designs can be

made. A local commercial car bumper was used as a reference to develop an alternative

material that is comparable with the existing material for the application of bumper. This

is an important step to ensure that the composite is viable and practical to be used as a

bumper fascia. The work continued with the manufacture of carbon fiber reinforced

polypropylene composite where the procedure were began with fiber preparation

followed by melt compounding process. Hot press was used to mold the composite into

a sheet so that the sample for analysis can be made. As to accomplish the second

objective, the research work was continued with sample analysis where the samples

were evaluated to investigate the mechanical and thermal properties. The analyses

consist of tensile, flexural, impact and hardness test, thermal gravimetric and dynamic

mechanical analysis. These results were finally compared with local commercial car

bumper properties.

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1.4 Thesis Layout

This thesis contains five chapters. Chapter One covers the introduction that includes the

background of carbon fiber and its application followed by the problem statement and

the objectives of the research. In Chapter Two, a survey is presented on carbon fiber

composite, matrix and the concept of bumper system. Subsequently, Chapter Three

describes the research materials and methodology used in the study. The results and

discussion are covered in Chapter Four where the analysis on experimental results is

included. The thesis ends with the Conclusion in Chapter Five. Here the results are

compared with the objectives and some recommendations for future works are also

presented.

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