Effects of Hygrothermal Conditions on Corona Aging of Silicone Rubber

In this research, high-temperature vulcanized silicone rubber was used as a sample to conduct hygrothermal corona aging test. Physicochemical and electrical performance of the silicone rubber were tested under different hygrothermal conditions. The results showed that the surface structure of the material was increasingly destroyed and even pulverized as humidity or temperature rises. Compared with the original samples, the static contact angle of the aged samples decrease significantly, and the static contact angle of the aged samples that exhibited pulverization expanded compared with those unpulverized samples due to the large amount of small-molecule siloxanes contained in the pulverized layer. The main chain and side chain of the aged silicone rubber were damaged to varying degrees. The absorption peaks of Si-O-Si and Si-CH
₃
bonds in the aged samples that exhibited pulverization were higher than those of the samples that did not exhibit pulverization, since the siloxane also contains Si-O-Si and Si-CH
₃
bonds. The aged material would combine with a large number of polar groups, leading to an enhanced polarity of the silicone rubber molecules and more dielectric loss of the material. The surface resistivity and volume resistivity of the aged samples were 6.45% and 70.29% of those of the original samples at 80°C and 95%, respectively, showing that corona discharge mainly damages the surface, rather than the interior of the material.