Fracture Toughness of Hybrid Carbon Fibre/Epoxy Enhanced by Graphene and Carbon Nanotubes

Carbon-based nanoparticles have attracted considerable attention in materials science and engineering fields as they can significantly improve the electro-thermo-mechanical properties of polymer-based materials. With the need of enhancing the mechanical property through the thickness direction of a carbon fibre reinforced polymer (CFRP) system, this study investigates the effect of graphene nanoplatelets (GNP), multi-walled carbon nanotubes (MWCNT) and their hybridisations on its Mode I interlaminar fracture toughness. Various nanoplatelet sizes and weight percentages are compared to prohibit their agglomeration in epoxy which can drastically reduce the mechanical properties of CFRP. The smallest GNP size, 1 μm, dispersed in the n-methyl-2-pyrrolidone solvent leads to an advanced 146% enhancement of Mode I interlaminar fracture toughness on the CFRP system. The acetone solvent is found less surface compatible with the nanoplatelets, but provides a simple and environmentally friendly manufacturing process. The hybrid GNP/MWCNT with 1wt% content dispersed in acetone solvent shows the synergistic effect and reaches a 120% enhancement of Mode I interlaminar fracture toughness of CFRP. Additionally, the application of the thin film hot press technique on nanoplatelets enhanced CFRP demonstrates an effective and promising solution to manufacture homogeneous multi-phase composites.