Nano-engineered design and manufacturing of high-performance epoxy matrix composites with carbon fiber/selectively integrated graphene as multi-scale reinforcements

Three different architectural designs are developed for manufacturing advanced multi-scale reinforced epoxy based composites in which graphene sheets and carbon fibers are utilized as nano-and micro-scale reinforcements, respectively. In the first design, electrospraying technique as an efficient and up-scaleable method is employed for the selective deposition of graphene sheets onto the surface of carbon fabric mats. Controlled and uniform dispersion of graphene sheets on the surface of carbon fabric mats enhances the interfacial strength between the epoxy matrix and carbon fibers and increases the efficiency of load transfer between matrix and reinforcing fibers. In the second design, graphene sheets are directly dispersed into the hardener-epoxy mixture to produce carbon fiber/epoxy composites with graphene reinforced matrix. In the third design, the combination of the first and the second arrangements is employed to obtain a multi-scale hybrid composite with superior mechanical properties. The effect of graphene sheets as an interface modifier and as a matrix reinforcement as well as the synergetic effect due to the combination of both arrangements are investigated in details by conducting various physical-chemical characterization techniques. Graphene/carbon fiber/epoxy composites in all three different arrangements of graphene sheets show enhancement in in-plane and out of plane mechanical performances. In the hybrid composite structure in which graphene sheets are used as both interface modifier and matrix reinforcing agent, remarkable improvements are observed in the work of fracture by about 55% and the flexural strength by about 51% as well as notable enhancement on other mechanical properties.