Moisture absorption process of epoxy resin and mechanical properties of its fiber composites

Abstract Epoxy resins are highly moisture absorbant when exposed to weather and environmental factors, which brings about a deterioration of durability and of mechanical properties in epoxy composites. In this paper, the effect of humidity on the durability and mechanical properties of epoxy resin and its composites was thoroughly studied for various time durations. It was found that moisture absorption increases linearly to the square root of time, following Fick's second law. Due to the resulting moisture absorption, the flexural strength and modulus of epoxy resin are impaired compared to dry samples. However, the strength retention rate of epoxy resin cast at a relative humidity of 60 % and 70 % are better than those of samples at relative humidity of 100 % and 90 %, a promising observation for assuring favorable application in high humidity environments. It is believed that this research will be beneficial for a wide and safe application of certain epoxy resin systems in harsh service environments.