Deterioration of CFRP and GFRP in Water at a Pressure of 800kg/cm²

Abstract

Carbon fiber or glass fiber unidirectionally reinforced epoxies (CFRP and GFRP) were immersed in water and 9% salt water at 20°C at a pressure of 800kg/cm² for various periods in the range from 1 to 12 months, and the measurements of the amount of water absorbed, flexural strength and interlaminar shear strength were carried out on them before and after immersion. The amount of water absorbed in CFRP in water or salt water was twice that absorbed in GFRP for the same period of immersion. The flexural strengths of CFRP and GFRP were decreased by 4-13 and 3-8%, respectively, by the immersion in water and salt water for twelve months, and their interlaminar shear strength 13-14 and 1-9%, respectively. The amount of water absorbed in salt water was less than that in water, and the decrease in flexural strength of CFRP and GFRP in salt water also was less than that in water. The flexural and interlaminar shear strengths of CFRP and GFRP decreased with increasing amount of water absorbed, and the decrease in flexural strength of CFRP was practically equal to that of GFRP at the same amount of water absorbed, but the decrease in interlaminar shear strength of CFRP was slightly greater than that of GFRP.