Hydrophobicity Improvement of Contaminated HTV Silicone Rubber by Atmospheric Plasma Jet Treatment

Hydrophobicity improvement of contaminated high temperature vulcanization (HTV) silicone rubber is of great significance to avoid risk of pollution flashover during wetting events. In the present investigation, low-temperature plasma jet produced by dielectric barrier discharge (DBD) under atmospheric pressure was used to quickly increase the hydrophobicity of contaminated HTV surface. Effects of the processing time, non-soluble deposit density (NSDD) and transfer time on the hydrophobicity improvement were studied and the long term stability of hydrophobicity was investigated. Experimental results proved that: hydrophobicity of contaminated HTV silicone rubber was significantly improved after a quick exposure to low-temperature plasma jet; and with the increase of exposure time, hydrophobicity transfer increased and a larger contact angle was obtained for the same transfer time. For the low discharge power plasma treatment, NSDD had a negative effect on hydrophobicity improvement and with the increase of the NSDD, increment of the contact angle decreased. In addition, hydrophobicity improvement had long term stability. Control experiment proved that interaction of plasma jet with silicone rubber played an important role in accelerating the transfer of low molecular weight (LMW) silane chains from the silicone rubber to the pollution layer, which finally resulted in the hydrophobicity improvement.