Improved Mode I fracture resistance of CFRP composites by reinforcing epoxy matrix with recycled short milled carbon fibre

This paper proves that incorporation of recycled short milled carbon fibre (SMCF) in epoxy resin can lead to the generation of significantly tougher carbon fibre reinforced polymer (CFRP) systems in a cost effective manner for infrastructural applications. Structural epoxy resin is modified by adding 5 and 10 wt.% of SMCF particles and the 'fracture toughness' of the modified matrix (GICM) is observed to be increased by 300% and 700% respectively. Subsequently, the SMCF modified epoxy resins were used to fabricate unidirectional carbon fibre reinforced laminates and tested under Mode I crack opening. The SMCF reinforcement showed 50% and 64% improvement in the laminates fracture toughness (GICC) after adding 5% and 10% SMCF by wt., respectively. Scanning electron microscope images of the fracture surface highlight improved debonding and pull-out mechanisms contributing to the additional fracture toughness, and at the same time there was no evidence of fibre clustering.