Loss and recovery of hydrophobicity on RTV coating surfaces

Studies are reported on decay and recovery of hydrophobic properties on clean and contaminated surfaces of silicone rubber based RTV coating. Treatment that led to hydrophobicity losses were water immersion and water condensation with and without a presence of dc electric field. Contact angles (receding angles) and surface leakage currents were measured on the treated surfaces. A suppression of the leakage current was observed and its link to the diffusion of the low molecular weight fraction from the polymer bulk and dry band arcing is discussed. Attempts aiming to restore the lost hydrophobic properties are also described. As a means of recovery, resting at ambient atmosphere, under UV irradiation, and in vacuum at elevated temperature, was applied. The efficiencies were verified through measurements of receding angles, surface leakage currents, and thermally stimulated depolarization currents