Investigation on the durability of e-glass/epoxy composite exposed to seawater at elevated temperature

In this manuscript, the durability of the E-glass/epoxy composite was determined under a seawater environment. The effect of harsh environment was investigated in terms of seawater absorption, microstructure and degradation in mechanical properties. E-glass epoxy composite specimens were conditioned in gulf seawater at 23^◦ C, 65^◦ C and 90^◦ C for the period of 12 months. It was observed that the mass of the samples increased after the immersion of 12 months at 23^◦ C and 65^◦ C whereas it reduced at 90^◦ C. The salt deposition was observed at the surface of specimens without any crack for the seawater conditioning at 23^◦ C and 65^◦ C. The swelling and crack formation were significantly visible on the surface of the specimen immersed for 12 months at 90^◦ C. It indicates that the degradation mechanism accelerated at elevated temperature results fiber/matrix debonding. The tensile test indicates slight variation in the elastic modulus and reduction in strength of E-glass epoxy composite by 1% and 9% for specimens immersed at 23^◦ C and 65^◦ C respectively. However, at 90^◦ C, the tensile strength sharply decreased to 7% and elastic modulus significantly increased in the exposure of 12 months. A prediction approach based on a time-shift factor (TSF) was used. This model predicted that the strength retention of E-glass/Epoxy composite will be reduced to 7% in 450 years after immersion in seawater at 23^◦ C. Lastly, the activation energy for the degradation of the composite was calculated.