Investigation of Degradation Behavior of Cohesion of Resin and Adhesion Interface under High Temperature and High Humidity Conditions

Abstract

In this study, deterioration of adhesive joint strength was investigated by lap joint specimens and butt joint specimens which were aged under high temperature and high humidity conditions. As a result, lap shear strength of lap joint specimens decreased with increasing aging time. From the results of surface observation and FT-IR analysis, it was confirmed that decrease of joint strength results from deterioration of the adhesive/adherend interface and degradation of cohesion due to hydrolysis of urethane bond. From the results of XPS measurement for butt joint specimens fractured by tensile test, it was clarified that H2O is adsorbed at the adhesive/adherend interface after aging. It was suggested that adsorption of H2O causes decrease of hydrogen bonding force combining adhesive/adherend interface and thus interfacial strength of the joint decreases.