Tailoring the Thermomechanical Properties of High Performance Aerospace & Automotive Composite Materials

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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 and design flexibility (load bearing only where required/reduced number of parts).
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 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 chemistry of a model epoxy resin composite matrix. A structure property map will be built allowing the properties of not only the matrix phase, but also the composite itself, to be tailored. A variety of resin and composite samples will be manufactured and tested in order to build the map. This in turn will lead to insight into the properties of both the matrix and composite, and also allow composite designers to use these materials more efficiently in the future.