Greener, cleaner, composites

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The overall aim of this proposal is to develop a fundamental understanding of the processing fabrication and performance of polymer based composites where the matrix material is either partially or wholly derived from bio-based feedstock. Moreover, the knowledge gained during this Fellowship will allow FAC Technology to increase commercial uptake in composite components manufactured from bio-based resin.Epoxy resin is the matrix of choice for high-performance composites due to their outstanding mechanical properties, including high modulus, high strength and favourable processing characteristics, e.g. low viscosity. Epoxy accounts for approximately 70% of the thermoset resin market worldwide. Diglycidylether of bisphenol A (DGEBA) is the most widely used monomer to formulate epoxy resins. DGEBA is mostly synthesised from fossil resources. Thus, there is clearly a pressing need to explore alternative thermoset chemistry that can be derived from renewable resources to reduce our dependence on fossil resources and our impact on the planet.Interest in resin and fibres derived from biological materials has surged in recent years, fueled by a desire to become more environmentally friendly and reduce dependence on dwindling fossil fuel supplies. Although epoxy polymers have generally good mechanical properties, they suffer from a lack of toughness due to the high degree of crosslinking in the cured thermoset. This lack of toughness has been alleviated in recent years by groups such as Kinloch et al at Imperial College London (Dr. Carolan was previously a Fellow with Prof. Kinloch). This is achieved by adding additives in to the resin blend before final cure of the component. Micron scale rubber particles, either preformed or formed via reaction induced phase separation have proven to be most effective. Bio-based resins also suffer from lack of toughness. To date, no extensive study on the 'toughenability' of bio-based resins (or hybrid resin containing a mixture of bio-based and conventional petroleum derived thermosets) has been carried out. 'Toughenability' refers to the amount by which the toughness of a thermoset polymer increases per unit additive added. It is currently unknown whether, or how well, the same toughening mechanisms will apply. Such knowledge is absolutely critical to increase the usage of more environmentally friendly resins from renewable feedstocks. The Future Leaders Fellowship will enable Dr. Carolan to be at the forefront of this transition in the UK composites industry.Indeed, there is some evidence in the literature to suggest that blends of petroleum derived resins and bio-derived resins will naturally phase separate during the curing reaction. Dr. Carolan has already demonstrated that by controlling the rate of the curing reaction, it is possible to profoundly influence the final microstructure of a phase separated system. This potentially means that the use of hybrid fossil- and bio-derived resins may offer synergistic benefits over the other. This will be investigated during the proposed Fellowship.The work proposed is multi-disciplinary in nature and will bridge the fields of materials science, chemistry and mechanical engineering. Moreover, by considering the effect of the molecular makeup of a resin, the Fellowship will bridge the length scales within a composite structure from the molecular level, through to the nanoscale and mesoscopic fibre-matrix interface behaviour and finally considering the composite structure itself. The element of time (or reaction rate) in determining the final microstructure will also be considered. This system level design approach, from molecule to component and from 'Pot to Part', is a truly innovative idea in industry and will allow FAC Technology to better design composite structure using less and less material while extracting ever more functionality from the structure and position Dr. Carolan as one of the industry leaders in composite materials in the UK.