複合材料 腐食環境下における切欠付きＧＦＲＰ丸棒の劣化に関する研究

Abstract

Corrosion tests were carried out by using GFRP notched bar specimen in order to establish the guideline of FRP bolt design. Pure water, sulfuric acid solution and sodium hydroxide solution were used as corrosive environment.The change of weight and retention of tensile strength were investigated for these environments. The degree of the degradation was remarkable in order of sodium hydroxide solution, sulfuric acid solution, and pure water.Microscopic observation indicated that glass fiber/resin interfacial debonding was generated by sulfuric acid solution. In sodium hydroxide solution, dissolution of the glass component from glass fiber and decomposition of matrix resin were caused. Colored layer that observed in sodium hydroxide solution was identified with corroded layer that was formed by hydrolysis of esters. The thickness of corroded layer was affected by the orientation of fibers. The effects of notch number (1-5) and pitch of notches (2.5-12.5mm) on the retention of tensile strength was discussed. The degradation of specimens with small number of notches was more noticeable than that with many notches. On the other hand, the decrease of tensile strength was smaller for smaller pitch of notches. These results were supported by the geometry of corroded layer near notches.