Greener, cleaner, composites

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.

The outcomes of this fellowship and its research findings will, in a broader context, have social, economic and environmental impacts. It will aid the achievement of the government's energy policy in addition to its contribution to the industrial and academic scientific and engineering community. Preventing energy shortfall and climate change are major national and global issues and it is recognised that advancing materials for energy applications is a key factor for addressing these. Increasing the uptake of lightweight composite materials plays a key role in that and championing the use of environmentally responsible composites, as outlined in this Fellowship, will be even more impactful in achieving these societal aims.

The fundamental understanding of materials processing and ultimate material and component behaviour will lead to the development of advanced material and component designs, with predictable behaviour. This, in turn will lead to the uptake of composites as a viable design choice in components and products that have, to date, been reluctant to embrace composite materials as a technology.

The work proposed in this Fellowship is impactful and strategically relevant and aligns directly with the UK government's composite strategy, 'Lightening the Load', to grow the native composites industry and ensure that the UK remains remains 'recognised as one of the world's leading places for the research and commercial exploitation of composite materials and processes'.

The principal beneficiary of this research will be FAC Technology, who, assuming a successful conclusion to this research will be in a position to bring to resin blends with outstanding durability and mechanical properties and partially or wholly manufactured from renewable resources. At the end of this Fellowship, FAC Technology will realistically be in a position to begin developing product offerings manufacture with renewable resins and it is not unreasonable that the products will begin to make an impact on markets within another one to three years (dependant on applications' regulatory environments).

This will have secondary benefits for the UK composites sector as it will cement the UK's positions as one the best places in the world to conduct leading R&D and translate that R&D into commercially successful products. FACT's existing supply chain for composites that may be manufactured as a result of this Fellowship is largely UK based.

The use of resins derived from renewable resources in the UK composites sector has a clear environmental impact. It will reduce our dependence on fossil fuels which contribute to global warming. Moreover, the production of renewable resources, e.g. growing the plants required will also act as a carbon sink and the commercial realties are that renewable feedstocks have the potential to less costly than the fossil-derived alternatives. This will drive down the cost of composite components and open the sector to markets that had previously been closed off for commercial reasons.