LAUSR

The influence of the fiber/matrix interface of pultruded glass fiber-reinforced polymer (GFRP) composites exposed to hygrothermal environments, including deionized water immersion and saltwater immersion at 20 ± 5 °C, 30 ± 1 °C, and 60 ± 1 °C for 180 days, was investigated. The effect of moisture absorption on tensile properties was discussed. After 180 days of immersion in deionized water, tensile strength and modulus of specimens decreased 25.7% and 26%, whereas the equivalent respective losses were 2.1% and 18.2% for specimens immersed in saltwater. The short-beam-shear test and the single-fiber fragmentation test were selected to reflect the degradation of macro- and micro-interfacial properties, respectively. After 180-day immersion in deionized water and saltwater at 60 ± 1 °C, the inter-laminar shear strength of specimens decreased 28.8% and 18.5%, respectively, and the corresponding interfacial shear strength decreased 53.2% and 23.5%, indicating that the diffusion rate of micro-interface was higher than that of macro-interface in the fiber direction. Immersion in all media leads to pronounced degradation in tensile strength, modulus, and inter-laminar shear strength. Furthermore, based on the change of interfacial strength and Weibull distribution, a prediction model was proposed to describe the degradation trends and temperature effects on ultimate bearing capacity of pultruded GFRP composites in hygrothermal environments.