ROOM TEMPERATURE VULCANIZED (RTV) SILICONE RUBBER COATINGS ON GLASS AND PORCELAIN INSULATORS: AN EFFORT TO MODEL THEIR BEHAVIOUR UNDER CONTAMINATED CONDITIONS

Alexandros Theodoridis - Michael G. Danikas - Johannes Soulis

   In polluted environments, coatings of room temperature vulcanized (RTV) silicone rubber are increasingly used on glass and porcelain insulators. During the lifetime of insulators, chemical changes and chemical reactions occur on the surface and in the bulk of the coatings. These reactions can lead to the formation of low molecular weight (LMW) silicone fluid. Factors that influence the quantity of low molecular weight silicone fluid in the coatings are investigated here. It is of great importance to know the behaviour of LMW silicone fluid in the coatings since the hydrophobicity of the latter depends to a great extent on the diffusion of the LMW silicone fluid to the coating surface. A mathematical model to describe the phenomenon of the diffusion of the low molecular silicone fluid from the bulk to the surface of the coating is proposed. It is the first time that such a model --- including many parameters --- is proposed. The proposed model deviates from the well known Fick's equation of diffusion. A relevant discussion about the applicability of the model is given.

Keywords: silicone rubber coating, outdoor insulator, low molecular weight silicone fluid

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