UNIVERSITY OF SOUTHERN QUEENSLAND
A FOUNDATIONAL INVESTIGATION OF
VINYL ESTER / CENOSPHERE COMPOSITE MATERIALS
FOR CIVIL AND STRUCTURAL ENGINEERING
A Dissertation Submitted by
Scott W Davey
B Eng (Civil) (Hons I)
For the award of Doctor of Philosophy
ABSTRACT
With the increasing use of fibre reinforced polymer (FRP) composites in civil engineering structures, there is a growing realisation of the need to develop new structural systems which can utilise the unique characteristics of these materials in a more efficient and economical manner. In many instances this will require the development of new materials tailored to address the unique performance and economic parameters of mainstream construction.
Over recent years, researchers at the University of Southern Queensland have pioneered the use of a new type of particulate filled polymer core material which greatly improves the robustness and cost effectiveness of FRP structural systems. These composite materials are composed of small hollow spherical fillers (microspheres) in a thermosetting polymer matrix. Initial research into these materials, including their feasibility in prototype structural elements, have shown these materials to have major potential for widespread application in structural composite systems.
One of the most promising classes of these materials investigated to date are vinyl ester / cenosphere composites, which utilise cenospheres derived from fly ash in a vinyl ester matrix. Previously reported studies into these materials have been restricted to initial surveys of material behaviour which sought to identify key parameters in achieving desired performance outcomes in the composite.
This dissertation presents the first in-depth investigation of these materials specifically as a core material option for civil infrastructure applications. The particular focus of this work is on the relationship of the vinyl ester matrix to the characteristics of the resulting composite. Several key matrix parameters were identified and assessed as to their influence on cure characteristics, fabrication operations, mechanical properties and the retention of such properties under elevated service temperatures.
CERTIFICATION OF DISSERTATION
I certify that the ideas, experimental work, results, analyses, software and conclusions reported in this dissertation are entirely my own effort, except where otherwise acknowledged. I also certify that the work is original and has not been previously submitted for any other award, except where otherwise acknowledged.
Signature of Candidate Date
Endorsement
Signature of Supervisor Date
Signature of Supervisor Date
ASSOCIATED PUBLICATIONS
Davey, S.W., Van Erp, G.M. and Marsh, R., 2001, Fibre Composite Bridge Decks – An Alternative Approach. Composites Part A, Vol 3A, No 9, pp. 1339-1343.
Davey, S.W., Van Erp, G.M. and Marsh, R., 2000, Fibre Composite Bridge Decks – An Alternative Approach. In: Proceedings of the ACUN-2 International Composites Conference. Sydney: University of New South Wales, pp. 216-221.
ACKNOWLEDGEMENTS
The completion of a PhD thesis is an arduous task, taking one to the limit and back again. The enormity of the task entails the assistance of a number of people to help bring it to a conclusion.
To my supervisory team –
Dr Stephen Ayers - Your advice and assistance has been unwavering. Thankyou for the considerable time and effort you have directed towards ensuring the completion of this PhD project.
Dr Tim Heldt - Thankyou for your guidance and counsel in many matters, particularly in helping me stay the course to complete my PhD, and in giving your time to review this dissertation.
Professor Gerard Van Erp - Thankyou for your support, for reviewing this dissertation and providing me the opportunity to complete my PhD studies. To my parents Bill and Christine Davey – Thankyou for your continual support throughout the completion of my PhD and in everything else that I do. I extend similar thanks to my brothers Aaron and Kim.
To my friends – You have stood by me through it all for which I am eternally grateful. People are often measured by the friends that they keep, so thankfully I will be judged favourably.
To the FCDD team, my fellow postgraduates and Research Office and Faculty staff – Thankyou for your advice, assistance and friendship over the years which has contributed to the successful completion of this work.
To all others who have assisted me, no matter how small a contribution, I give you my thanks.
“That Which Does Not Kill Us Makes Us Stronger”
TABLE OF CONTENTS
Page
ABSTRACT i
CERTIFICATION ii
ASSOCIATED PUBLICATIONS iii
ACKNOWLEDGEMENTS iv
TABLE OF CONTENTS v
CHAPTER 1. INTRODUCTION
1.1 Introduction 1
1.2 Background 1
1.3 Aims and Objectives 3
1.4 Scope and Limitations 4
1.5 Structure of Dissertation 5
1.6 References 6
CHAPTER 2. A REVIEW OF CONSTITUENT OPTIONS FOR VINYL ESTER / CENOSPHERE COMPOSITES
2.1 Introduction 7
2.2 Composition Basics 8
2.3 Review of Previous Research 8
2.4 Vinyl Ester Polymers 11
2.4.1 Basic Chemistry 11
2.4.3 Modified Vinyl Ester Grades 14 2.4.4 Modification of Toughness 14 2.4.5 Reduced Emissions During Processing 18 2.4.6 Elevated Temperature Performance 22 2.4.7 Improved Chemical Resistance 26
2.5 Curing Vinyl Ester Polymers 27
2.6 Cenospheres 33
2.7 Discussion 39
2.8 Conclusions 43
2.9 References 44
CHAPTER 3. THE CURE BEHAVIOUR OF VINYL ESTER / CENOSPHERE COMPOSITES
3.1 Introduction 50
3.2 Experimental Investigation 54
3.2.1 Materials 55
3.2.2 Experimental Techniques 58 3.2.2.1 Differential Scanning Calorimetry 58 3.2.2.2 Cure Assessment of Cenosphere Composites 62
3.3 Results and Discussion 63
3.3.2.1 Influence of Peroxide Initiator Type 93
3.3.2.2 Influence of Accelerator Level 98
3.3.2.3 Influence of the Oligomer Molecular Weight 100
3.4 Summary and Conclusions 103
3.5 References 104
CHAPTER 4. THE PROCESSING CHARACTERISTICS OF VINYL ESTER / CENOSPHERE COMPOSITES 4.1 Introduction 105
4.1.1 Review of Processing Characteristics 106
4.1.2 Material Combinations for Investigation 111
4.1.3 Characterisation Parameters 112
4.2 Experimental Investigation 113
4.2.1 Materials 113
4.2.2 Experimental Techniques 113
4.2.2.1 Viscosity Measurement Using the Brookfield Test Method 115
4.2.2.2 Shrinkage Measurement Using a Linear Method 116
4.2.2.3 Shrinkage Measurement Using a Block Method 117
4.3 Results and Discussion 118
4.3.1 Characterisation of Viscosity Behaviour 118
4.3.1.1 Influence of Filler Volume Fraction 118
4.3.1.2 Influence of Styrene Concentration 122
4.3.2 Characterisation of Shrinkage Behaviour 126
4.3.2.1 Influence of Filler Volume Fraction 126
4.3.2.2 Influence of the Oligomer Molecular Weight 129
4.3.2.3 Influence of Styrene Concentration 133
4.4 Summary and Conclusions 138
4.5 References 140
CHAPTER 5. THE MECHANICAL PROPERTIES OF VINYL ESTER / CENOSPHERE COMPOSITES 5.1 Introduction 142
5.1.1 Background 143
5.1.2 Characterisation Parameters 143
5.2 Experimental Investigation 145
5.2.1 Materials 145
5.2.2 Experimental Techniques 146
5.2.2.1 Characterisation of Tensile Properties 147
5.2.2.2 Characterisation of Compressive Properties 148
5.2.2.3 Characterisation of Flexural Properties 149
5.2.3 Sample Details 150
5.3 Results and Discussion 151
5.3.1 Influence of Specimen Fabrication 151
5.3.2 Strength Characteristics 155
5.3.3 Stiffness Characteristics 162
5.3.4 Poisson’s Ratio 164
5.4 Summary and Conclusions 166
5.5 References 168
CHAPTER 6. THE TRANSITION BEHAVIOUR OF VINYL ESTER / CENOSPHERE COMPOSITES 6.1 Introduction 170
6.1.2 Characterisation of Glass Transitions 172
6.1.3 Interpretation of DMA Data 174
6.2 Experimental Investigation 178
6.2.1 Materials 178
6.2.2 Experimental Techniques 179
6.2.2.1 Dynamic Mechanical Analysis 179
6.3 Results and Discussion 181
6.3.1 Using the Glass Transition Temperature to Gauge Elevated Temperature Performance 181
6.3.2 Transition Behaviour of Unfilled Vinyl Esters 184
6.3.2.1 Influence of Initiator Concentration 184
6.3.2.2 Influence of Peroxide Initiator Type 189
6.3.2.3 Influence of Accelerator Level 190
6.3.2.4 Influence of the Oligomer Molecular Weight 194
6.3.2.5 Influence of Styrene Concentration 198
6.3.3 Temperature Performance After an Ambient Temperature Cure 201
6.3.4 Transition Behaviour of Filled Vinyl Esters 203
6.3.4.1 Influence of Filler Volume Fraction 204
6.3.4.2 Influence of the Oligomer Molecular Weight 208
6.4 Summary and Conclusions 213
6.5 References 216
CHAPTER 7. CONCLUSIONS 7.1 Overview 217
7.2 Key Findings 218
7.3 Primary Conclusions 221
7.4 Recommendations for Future Research 224
7.4.2 Additional Foundational Research 225
7.4.3 Production Investigations 226
LIST OF TABLES 227
LIST OF FIGURES 231
APPENDIX A. DIFFERENTIAL SCANNING CALORIMETRY (DSC)
AND THERMOCOUPLE MONITORING RESULTS
APPENDIX B. EXPERIMENTAL DATA AND RESULTS FOR THE
DETERMINATION OF THE TENSILE PROPERTIES OF VINYL ESTER / CENOSPHERE COMPOSITES
APPENDIX C. EXPERIMENTAL DATA AND RESULTS FOR THE
DETERMINATION OF THE COMPRESSION PROPERTIES OF VINYL ESTER / CENOSPHERE
COMPOSITES
APPENDIX D. EXPERIMENTAL DATA AND RESULTS FOR THE
DETERMINATION OF THE FLEXURE PROPERTIES OF VINYL ESTER / CENOSPHERE COMPOSITES
