Tailoring the Natural Toughness in Epoxy Resins
There is a rising need to create high performance, lightweight and strong yet tough materials for use in various industries including aerospace (civil, military aircraft), automotive (sports, utility, emergency vehicles) and others (civil engineering etc.). The use of composite materials (consisting of long fibre reinforcements in a thermosetting polymeric matrix) to meet this need is now commonplace for several reasons. These include significant weight savings over traditional materials, design flexibility (load bearing only where required/reduced number of parts), corrosion resistance and thermal/electrical insulation. The matrix phase in such composite materials plays several important roles, including binding the reinforcement together, maintaining shape and stress transfer onto the reinforcements but also it enhances properties. While fibres are excellent at improving tensile stiffness and strength, a well-chosen matrix will provide shear and compressive stiffness but also, critically, toughness. The ability to survive impact from a relatively small everyday strikes to a potentially catastrophic event (ballistic, blast) is one of the most important questions requiring research in composites today. Strategies for improving the existing toughness in thermosetting polymers such as epoxy resins include the addition of rubber particles and dissolved/phase separated thermoplastic polymers. Whilst using these approaches will increase the toughness it is often difficult to correspondingly maintain the strength and stiffness of the material. However, high performance epoxy resins invariably have some natural (built-in) toughness courtesy of the reacted epoxy ring or cooperative rotation of the backbone phenyl rings. This provides a mechanism to dissipate energy and therefore improves the toughness of the material. As part of a wider research effort into this phenomenon, this project will investigate the effect of systematically altering the rotation of the backbone phenyl rings in a model epoxy resin matrix. The effect this has on the properties of the resins will be measured and correlated with the toughness in composite materials. The rotation of the rings will either be hindered (by making resins with brominated phenyl rings which are less able to rotate due to steric hindrance) or promoted (by making resins with a less sterically hindered epoxy). The amount of natural toughness present in the resins will be quantified using dynamic mechanical thermal analysis which shows the location and extent of the sub-ambient beta transition which directly contributes to composite toughness.
Candidates should be self-funded, sponsored, or applying for Scholarships. The University and the Faculty of Engineering award PhD scholarships for Home, EU, and International students on a competitive basis every year. The deadline for Faculty/University Scholarships is February each year - for more information see: www.shef.ac.uk/postgraduate/research/scholarships
Candidates should have or expect to gain a good Honours degree with 2i or above in Materials Science and Engineering or related discipline.
If English is not your first language then you must have International English Language Testing Service (IELTS) average of 6.5 or above with at least 6.0 in each component.
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Materials Science and Engineering
FTE Category A staff submitted: 34.80
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