The influence of voids on the hydrothermal response of carbon fibre reinforced plastics

Measurements are reported of the shear modulus, strength and strain at failure of carbon fibre reinforced plastics exposed to the effects of temperature and temperature plus water. Two types of specimen were employed, one with a low void content and one with a high void content. Properties were determined either at room temperature after specimens had been fully dried, or at high temperature and in some cases at high temperature and under water. For good, low void content specimens, any effects of temperature and water were completely removed by drying. For specimens containing more than 1 vol% voids this was not so. Measurements at high temperature indicated a fall-off in stiffness and strength for either type of specimen, and for void containing specimens an increase in the strain at failure indicative of bond disruption. The added effects of water were complex.