Effect of Temperature on the Evaluation of Degradation Condition of Silicone Rubber

Surface free energy has negative temperature dependence. The decrease of surface free energy of solid increases the hydrophobic property; however, the decrease of the one of liquid decreases the hydrophobic property. In this study, the effect of temperature on the evaluation of degradation condition of silicone rubber is studied. Hydrophobicity of silicone rubber was measured by using both the image data analysis of the sprayed water droplets on the sample surface and the contact angle measurement. Using image data analysis of these water droplets, STRI's hydrophobicity class (HC) and contact angle (thetas) are evaluated automatically. Surface roughness of the silicone rubber also affects the hydrophobic condition of the surface. In this study, hydrophobic condition, surface roughness, dielectric properties and the amount of ATH filler are compared to diagnose the degradation condition of silicone rubber. Comparing of these evaluation results can define the degradation of polymer insulator more accurately.