Mechanical and thermal properties of carbon fiber epoxy composite with interlaminar graphene at elevated temperature

In this study we examined the mechanisms of graphene reinforcement in CFRP and the resulting improvements to mechanical strength, resistance to crack propagation, and thermal conductivity at elevated temperatures. Plant-based graphene nanoplatelets (pGNP), produced from renewable biomass and with flakes 3–10 layers dispersed in alcohol/water was applied via spray at 2.3 g/m2 to unidirectional carbon fiber/epoxy prepreg, creating an interlaminar nanocomposite. Raman spectroscopy, XPS, and DMA show polymer crosslinking with graphene surface groups and the resulting restriction of side chain movement. These restrictions improve composite performance at ambient and elevated temperatures, extending the damage process zone and increasing fracture toughness. Interlaminar pGNP improved Mode I fracture toughness at crack initiation by 145% at 20 °C and 126% at 90 °C, with fracture toughness improved by 53% and 52% during propagation at 20 °C and 90 °C, respectively. Mode II fracture toughness was not changed at 20 °C and improved 55% at 90 °C.