Effect of surface condition on the evaluation of hydrophobicity of polymer insulator

Hydrophobicity of polymer surface is one of the degradation indices of polymer insulator material and is usually evaluated by using an image of sprayed water on the sample surface, which is called STRI or spray method. In this study, the effects of parameters to the evaluation of hydrophobicity of silicone rubber are studied. The parameters include surface roughness, measurement temperature, water absorption, weight percent of ATH filler and surface treatment of fillers such as ATH and silica. Hydrophobicity is evaluated by using the image analysis of sprayed water, the dynamic drop test and also the contact angle of a water droplet.