Hydrophobicity Test of Silicone Rubber Based on Thermogravimetric Analysis

To study the hydrophobicity and the transfer of hydrophobicity of silicone rubber, experiments were conducted under three conditions (low-temperature ashing, room-temperature ashing, and low-temperature salting) on new silicone rubber products. Then the surface hydrophobicity of the material after cleaning the contaminants was measured using the classification of water spray, and the change laws of low molecular-weight substances in the core layer and the surface of silicone rubber samples were studied using the thermogravimetric analysis. The results showed that the low molecular-weight substances, namely the hydrophobic substances, were a typical type of siloxane. After pollutants accumulated on the surface of the silicone rubber, the surface hydrophobicity of the material declined continuously, and the contents of hydrophobic substances in the surface and the core layers reduced with fluctuations at a rate being directly proportional to the ambient temperature. The content and the decrease rate of hydrophobic substances in the surface were slightly higher than those in the core layer. The ashes in the contaminants propelled the transfer of the hydrophobic substances while salts inhibited the transfer. However, the presence of salts accelerated the hydrolysis of silicone rubber molecules in the material surface. The experimental results provide reference for the daily maintenance of composite insulators of electric power enterprises.