Microstructure and Mechanical Properties of Epoxy – Rice Husk Ash Composite.
ABSTRACT
This study is about the production and characterization of epoxy-rice husk ash composite. Composites were produced at 10%,20%,30%,40% and 50% volume fraction of Rice Husk Ash(RHA) fillers and the epoxy was cast neat at 0%RHA which served as the control.
The microstructure of the composites were studied with Scanning Electron Microscopy(SEM) and Energy Dispersive X-ray Spectroscopy(EDX).
Mechanical properties of the composites such as tensile properties(tensile stress, tensile strain, Young’s modulus, tensile strength and percentage elongation at fracture),compressive strength, toughness.F
lexural strength and hardness were experimentally determined in the engineering labouratory using hounsfield (monsanto) tensometer, charpy v-notch impact testing machine, flexural testing machine and Rockwell hardness testing machine.
The Scanning Electron Microscopy (SEM) analysis showed that interfacial interactions existed between the rice husk ash particles and the epoxy matrix.
Energy Dispersive X-ray Spectroscopy (EDX) analysis indicated that interfacial reactions existed between the epoxy matrix and the rice husk ash particles because the composites did not contain homogenous elements.
However each of the composites contained C,O,Si and Cl while the cast neat epoxy(control) contained C,O and Cl. Results of the mechanical property tests showed low gain in hardness, toughness, flexural strength and Young’s modulus.
The tensile properties showed: that at 40%RHA the highest tensile strength of 37.006MPa was obtained, the cast neat epoxy (control 0%RHA) had the best Young’s modulus of 356.538MPa and percentage elongation at fracture improved from 1.3% to 2.0% as volume fraction of rice husk ash increased from 0% to 10%,20%,30%,40% and 50%.
Increasing the volume fraction of rice husk ash from 0% to 10%, 20%,30%,40% and 50% led to decrease of these mechanical properties: toughness from 2.0J to 0.3J, hardness from 344hardness value to 144 hardness value and flexural strength from 6.0Mpa to 1.50Mpa.
There was significant improvement in the compressive strength of the composites from 15.75MPa to 18.75MPa as the volume fraction of rice husk ash increased from 0% to 10%,20%,30%,40% and 50%.
It was deduced from the study that epoxy-rice husk ash composite is suitable for engineering applications subjected to compression.
Surface coating of rice husk ash could be used to improve its adhesion to the epoxy matrix in order to enhance the mechanical properties of the composites for other engineering applications.
TABLE OF CONTENTS
Title Page – – – – i
Approval Page- – ii
Certification – – iii
Dedication – – – iv
Acknowledgement – – v
Abstract – vi
Table of Content – – vii
List of Figures x
List of Tables xiii
List of Plates – – xv
CHAPTER ONE: INTRODUCTION
CHAPTER TWO: LITERATURE REVIEW
- Overview of Composites – – – – – – 9
- Rice Husk Ash – – – – – – – – 14
- 2.1 Industrial Applications of Rice Husk Ash – – – – 15
2.3 Epoxy – – 16
2.3.1 Curing of Epoxy Resins – – 17
2.5.2 Engineering Applications of Epoxy 17
2.4 Compressive Strength – – 18
2.5 Toughness – 19
2.6 Flexural Strength – 19
2.7 Hardness — 19
- Tensile Properties – – 20
2.8.1 Stress – – 20
2.8.2 Strain – 20
- Tensile Strength – – – – – – – 21
- Young’s Modulus – – – – – – – 22
- Elongation at Fracture – – – – – – 22
- Scanning Electron Microscopy – – – – – 23
- Components of a Scanning Electron Microscope – – 25
- Energy Dispersive X-Ray Spectroscopy – – – – 26
- Applications of Scanning Electron Microscopy – Energy Dispersive
X-Ray Spectroscopy Analysis – – – – – 29
- Microstructure – – – – – – – – 30
- Adhesion and Cohesion – – – – – – 31
- Calculation of Fiber Volume Fraction – – – – 32
CHAPTER THREE: MATERIALS AND METHODS
3.1 Materials – — 33
- Matrix Material – – – – – – – 33
- Filler Material – – – – – – – – 33
3.2.0 Methods – – 34
- Preparation of Composite Mould – – – – – 34
- Composite Fabrication – – – – – – 35
- Mechanical Property Tests – – – – – – 37
- Tensile Testing of Composite Samples – – – – 37
- Compressive Strength Test – – – – – – 38
- Toughness Test – – – – – – – 38
- Hardness Test – – – – – – – – 39
- Flexural Strength Test – – – – – – 39
- Scanning Electron Microscopy and Energy Dispersive X- Ray Spectroscopy Analysis – – 40
CHAPTER FOUR: RESULTS AND DISCUSSION
4.1 Results – – 42
4.1a Results for Mechanical Properties – – – – – 43
4.1b Results of Scanning Electron Microscopy Analysis – – 53
- c Results of the Energy Dispersive X-Ray Spectroscopy Analysis 61
- Discussion of Results – – – – – – – 70
- Mechanical Properties – – – – – – 70
4.2.1a Tensile Properties – 70
4.2.1b Toughness – – 72
4.2.1c Hardness – 73
4.2.1d Flexural Strength – 73
- e Compressive Strength – – – – – – 73
- Scanning Electron Microscopy Analysis – – – – 74
- Energy Dispersive X-Ray Spectroscopy Analysis – – 76
CHAPTER FIVE: CONCLUSION AND RECOMMENDATIONS
- Conclusion – – – – – – – 78
- Recommendations – – – – – – – 79
References – 80
INTRODUCTION
1.1 Background Information
Most times engineers are faced with the task of developing a new material that has light weight, low cost and good mechanical properties. A promising option to this task is to use a low density particulate material like rice husk ash in a polymer matrix to form a polymer composite.
Rice husk ash is a by-product of combustion of rice husk at rice mills (Zemke and Woods, 2008). Researchers are currently investigating the use of ash for composite production since ash is an abundant agricultural waste, is renewable and has low bulk density.
Rice husk ash had been applied in other areas like manufacturing insulating powder, production of refractory bricks, cement production and sandcrete block production. However there are limited applications of rice husk ash in composite production.
A composite material is a microscopic or macroscopic combination of two or more distinct materials with a recognizable interface between them. In a composite material the constituents do not dissolve or merge completely in one another.
Normally the components in a composite material can be physically identified and they exhibit interface between one another. A particulate composite consists of a matrix reinforced with a dispersed phase in form of particles.
Soft particles like coir dust, rice husk flour, baggase ash, sawdust and rice husk ash can be dispersed in a harder matrix to improve machinability and reduce coefficient of friction (Lake,2002;Jiquao et al, 2010).
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