Effect of Hydraulic Pressure on Deteriolation of CFRP and GFRP in Water

Abstract

Carbon fiber or glass fiber unidirectionally reinforced epoxies (CFRP or GFRP) were immersed in water, and 4, 9 and 23% salt water at 20°C at various pressures in the range from 50 to 1000kg/cm² for one month, 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 was more in CFRP than in GFRP, and it decreased with increasing pressure and increasing concentration of salt in both of CFRP and GFRP. The flexural strength and the interlaminar shear strength of CFRP were decreased by 5.0 and 7.5% on the average, respectively, by the immersion in water and salt water under pressure, and those of GFRP by 1.2 and 1.9%, respectively. In this case, the flexural strength as well as the amount of water absorbed in CFRP decreased as the immersion pressure increased. The flexural and interlaminar shear strengths of CFRP and GFRP after immersion were not lower in salt water than in water. From these results the effect of hydraulic pressure was considered to decrease the flexural strength of CFRP.