Fractal analysis on the recovery of contaminant properties of silicone rubber insulator against acid rain

The relation of hydrophobicity and surface roughness of high temperature vulcanizing silicone rubber (HTV SR) insulator aged in artificial acid rain is investigated. The rough surface of aged insulator can present the appearance of a fractal surface. After aging in acid rain, the insulator surface becomes rougher owing to the dissolution of inorganic filler, and the hydrophobic groups in surface layer are worn away. The fractal surface of aged insulator for lack of hydrophobic material may become hydrophilic so that surface hydrophobicity degrades. In the dry condition, the hydrophobic polymer liquid in bulk diffuses and migrates to surface layer. The fractal surface of aged insulator with the supplement of hydrophobic polymer liquid may become hydrophobic. The degraded hydrophobicity is therefore restored to some extent