Surface Potential Decay and Hydrophobicity of Three Liquid Silicone Rubbers Before and After Direct Fluorination

Due to many desired properties, liquid silicone rubber (LSR) is the first choice for external insulation of all kinds of bushing in substations or converter stations. This report compares basic electrical properties and hydrophobicity of three commercial LSRs before and after direct fluorination. They are fluorinated in a laboratory reactor with the same fluorination temperature, pressure and time, using the same F2/N2 mixture. This report shows the effect of SR formulation on the basic electrical properties, and further reveals the effect of the formulation on the changes in basic electrical properties caused by the fluorination. Measurements of water contact angles show that the fluorination always results in final high hydrophobicity for three LSRs, regardless of the initial contact angle after the fluorination. Based on ATR-IR and XPS analyses and SEM observation, this report characterizes the physicochemical characteristics of the SR fluorinated layers.