A Study on the Aging Resistance of Injection-molded Glass Fiber Thermoplastic Composites

In this paper, the aging resistance of glass fiber-reinforced thermoplastic composites was discussed and analyzed in terms of the effects of hygrothermal aging and the time-temperature dependence. Accelerated hygrothermal aging tests, static flexural tests at different temperatures and speeds, and dynamic mechanical analysis tests at multiple temperatures and frequencies were carried out. Hygrothermal aging reduces the tensile properties and heat resistance of GF/PA and GF/PET, although the influence on GF/PA was greater than that on GF/PET. However, hygrothermal aging does not affect the thermal decomposition temperature. For the GF/PET composites, both the static flexural and dynamic mechanical properties were time and temperature dependent. It was found that increasing the temperature and decreasing the loading rate had equivalent effects on reducing the flexural strength and modulus. The time-temperature superposition principle was applied to the static flexural modulus of GF/PET. According to the master curve obtained by the time-temperature superposition principle, it was predicted that the static flexural modulus of GF/PET composites will decrease by 69.4% over 10 years at the reference temperature of 30 °C.