The Effect of Silicone Rubber on the Relative Permittivity and Hydrophobicity of Gum Rosin As an Alternative Outdoor Insulator Coating

The performance of outdoor ceramic insulators can be improved by insulator surface coating to increase electrical capabilities. One of the requirements for a material is good to be used as an insulator coating is that it has a relative permittivity of around 2–10 and has high hydrophobicity properties. Gum rosin is the remainder of the distillation of pine tree sap. The chemical formula for gum rosin, also known as colophony, is C2oH30C02. This product has hydrophobic characteristics, adhesive promoter, and high viscosity so it can be used as an insulator. In previous works, research had been conducted on insulator coatings using gum rosin, but the results were less than optimal. The elements contained in gum rosin consist of C and O elements based on the SEM-EDX test results. It is necessary to add silicone rubber which has Si elements in it to increase hydrophobicity and surface resistance, as well as reduce leakage current. Therefore, in this research room temperature vulcanized silicone rubber (RTV SiR) was added to improve the performance of the outdoor insulator. This research aims to analyze the effect of silicone rubber on the relative permittivity and hydrophobicity of gum rosin. The experiment results reveal that the optimum material was the gum rosin 5 wt. % + RTV SiR 95 wt. % sample which has the largest permittivity of 5.27 and the largest contact angle of 96° in polluted conditions. From this research, it can also be concluded that mixing gum rosin and RTV SiR can increase hydrophobicity compared to that of RTV SiR alone or gum rosin alone which can be used as an alternative coating material for outdoor ceramic insulators.