Surface hydrophobicity of silicone rubber under natural tropical conditions

This paper reports the influences of natural tropical conditions in Bandung, Indonesia on the surface hydrophobicity of the HTV and RTV silicone rubber with different filler contents. Samples of HTV and RTV silicone rubber with different filler contents were installed in an open-air plane for natural tropical climate aging. To know the effect of UV radiation, some of the samples are protected from natural UV by using a shield. The changes of the surface hydrophobicity were monitored periodically by using static contact angle measurement. The results of measurement during 72 weeks on the samples with shielding indicated that the hydrophobicity was slightly effected by the changes of tropical climate, while samples exposed without shielding showed the increase of hydrophobicity (contact angle ≈145°) with the increase of natural pollutant on the surface. The pollution layer and clean surface of the sample was observed with scanning electron microscopy (SEM) which showed that the pollution layer has higher roughness than clean surface of silicone rubber