Characteristics of weathershed materials for polymer insulators by accelerated aging tests

Weathershed materials for polymer insulators are organic, and so aging deterioration is unavoidable. We made fundamental investigations of the aging of silicone rubber sheets by accelerated aging tests in the laboratory. The evaluation method of surface hydrophobicity by contact angle was examined. The effect of time duration after placing a water droplet on the specimen surface until taking a photograph of the contact angle was clarified. We also clarified that the water droplet for accurate receding contact angle measurement should be prepared by sucking back water until confirming the shrinkage of the periphery of the water droplet. Based on such preliminary investigation we made aging tests introducing the recovery time of hydrophobicity in the cyclic sequence. Test results are presented in the paper.