The combined effects of load, moisture and temperature on the properties of E-glass/epoxy composites

The properties of an E-glass/epoxy composite were examined before and after mechanical loading and moisture conditioning. Preliminary results indicate that the modulus, strength, and strain of the E-glass/epoxy composite material are affected by the presence of moisture and mechanical loading when compared to control specimens. At shorter durations of conditioning at room temperature, a slight increase in strength and a slight decrease in modulus were observed; and at longer durations, 3000 h, a noticeable reduction in strength and strain-to-failure was observed. Specimens conditioned under stress, in water at 65 °C for 1000 h exhibited higher loss in modulus. It is speculated that constant stress may have a positive effect in short-term, and that extended exposure to moisture at room temperature leads to brittle failure while exposure at high temperatures may lead to ductile failure of E-glass/epoxy composites.