The effect of moisture ingress on mode-I fracture toughness of carbon/epoxy laminates with hybrid toughening using core-shell rubber particles and thermoplastic veils

Core-shell rubber (CSR) particles and thermoplastic polyphenylene sulphide (PPS) veils are used to achieve hybrid interlaminar toughening of carbon/epoxy laminates by using vacuum assisted resin infusion and out-of-autoclave curing. Double cantilever beam (DCB) tests are carried out to investigate the effect of hydrothermal conditioning on the mode-I fracture energies and R-curve behaviour. It is shown that interlaminar fracture toughness is significantly enhanced by hybrid toughening (e.g. ~246% in mode-I initiation energy). However, the hybrid toughened specimens are more sensitive to moisture ingress compared to the baseline and non-hybrid toughened specimens. The results demonstrate that the mode-I fracture energies of hybrid toughened laminates are decreased after hydrothermal conditioning, and the facture energies are further reduced when the moisture is removed (i.e. ~31% and ~24% lower than the original initiation and propagation energies).