Durability of thermoset composites in seawater environment

After three years of exposure to seawater, E-glass/epoxy composite showed a slight change in strength and modulus at room temperature, and a 38% decrease in strength at an elevated temperature of 65 °C. E-glass/urethane composite showed a 35% decrease in strength at room temperature and 58% decrease in strength at 65 °C. The tensile modulus of the glass/polyurethane exhibited a minor change after three years of exposure at room temperature and a slight increase after exposure at 65 °C. There was a significant reduction in strain to failure of both composite materials, ranging from 4% at room temperature to 100% at 65 °C. After extended exposure to seawater, both composites exhibited brittle failure; and the reduction in strength and strain at failure indicates degradation in the matrix and at the interface between.