Residual Tensile Properties of Carbon Fiber Reinforced Epoxy Resin Composites at Elevated Temperatures

Carbon fiber reinforced epoxy resin composites have attracted great attention in high pressure hydrogen storage for its light weight and excellent mechanical properties. The degradation of residual mechanical properties at elevated temperature from 20 °C to 450 °C were studied experimentally. The effects of temperature on the tensile strength and failure mode of the composite specimens with stacking sequences of 0°, 90° and ±45° (labeled as CF0, CF90 and CF 45) were systematically analyzed followed by the fracture surfaces examination. Results show that the tensile strength residual ratios of the three kinds of specimens decrease significantly with heating temperature increasing. In particular, the decomposing temperature of the resin matrix exerts the largest effects on the degradation of tensile strength of CF0 specimen within 450 °C. While the loss of tensile strength of CF90 and CF45 specimens is dependent on the thermal softening of epoxy resin which has closely related to the glass transition temperature. Furthermore, the debonding and fiber softening appeared in the CF0 specimens when the temperature reached 450 °C. For CF90 specimens, the degradation of bonding strength of epoxy could be found at 150 °C, and regarding CF45 specimens, delamination cracking between plies occurred extensively when the temperature above 125 °C.