Study on electrical and chemical characteristics of heat-treated FRP

An object of the present study is to induce a surface deterioration mechanism by heat deterioration of the epoxy/glass fiber, which is a polymeric material for outdoors. Experiments revealed that, below 200°C, the surface became hydrophobic owing to evaporation of low molecular substances and cross-linking of unreacted substances. Such hydrophobic surface resulted in the improvement of contact angle, surface resistance rate, and surface potential decay, leading to improved insulating property. However, above 200°C, excessive heat energy caused oxidation and destruction of bonds, resulting in deterioration of insulating property. Further, X-ray photoelectron spectrum analysis showed that the value of carbon peak increased till 200°C, while it decreased 250°C because of surface oxidation. In other words, below 200°C, the insulating property was improved because the surface became hydrophobic due to cross-linking of unreacted substances, but at above 250°C, excessive heat energy caused destruction of bonds, resulting in rapid activation of surface.