Abstract
The surfaces of poly [p-phenylene benzobisoxazole] (PBO) fibres were grafted with epichlorohydrin by a gamma (γ)-ray irradiation method. The influence of irrdiation dose on the interfacial shear strength (IFSS), interlaminar shear strength (ILSS) and the fibre wettability were investigated. In addition, the fibre surface composition, and the shear fracture topography of PBO fibre/epoxy resin composites were analysed by X–ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. The results indicate that a dose of 30KGy was the optimal condition for PBO fibre surface modification. The oxygen content of the irradiated PBO fibres was 22% higher than that of the untreated ones, and chlorine atoms were introduced onto the surface of the fibres through grafting actions between epichlorohydrin and PBO. The wettability of the epichlorohydrin-grafted PBO fibres was significantly increased, and the values of IFSS and ILSS of its composites were increased by 70% and 135%, respectively.
SEM shows that the improved interfacial adhesion resulted in a change in the failure mode of PBO fibre/epoxy composite from an adhesive-type interfacial failure to a cohesive-like matrix failure.