Original paper(Vol.46 No.7 pp.814)

Study on mechanism of decrease in strength of GFRP immersed in weak acid solution by SAM

Akamatsu Shigenori; Seo Kenji; Kusaka Masahiro; Urakami Yoshiki; Maeda Tsuyoshi

Abstract:Glass fiber reinforced vinyl ester resins (GFRP) were immersed in weak acid solution (1% sulfuric acid water) at 40 deg. for various periods from 0 to 12 months. After drying at room temperature for one week, the tensile and the bending tests were carried out on them. The tensile strength of GFRP decreased slowly with increasing immersion time, and the bending strength was degraded rapidly with increasing immersion time in the early stage. From the test results, it was considered as follows:
(1) The decrease in strength of GFRP was due to the damage of glass fibers.
(2) The damage of glass fibers proceeded from the surface to the inside of GFRP.
In order to confirm this mechanism of decrease in strength, the inside of GFRP was observed nondestructively with a scanning acoustic microscope (SAM). From the observation results, it was confirmed that the damage of glass fibers was caused by corrosion by weak acid solution, and the corrosion of glass fibers was produced in GFRP. Therefore, the mechanism of decrease in strength of GFRP due to immersion in weak acid solution was clarified by this study.

Key Words:decrease in strength, weak acid solution, GFRP, tensile strength, bending strength, scanning acoustic microscope, nondestructive observation