The relationship between microstructure and hydrophobicity of service-aged silicone rubber insulators

Silicone rubber insulators aged after years of operation. To evaluate the insulation condition of service-aged silicone rubber insulators, the relationship between micro structure and hydrophobicity is presented for service-aged silicone rubber insulators in this paper. According to industry standards, the hydrophobicity property of silicone rubber insulators are classified by contact angle method and water spray classification. Results showed the silicone rubber insulators still kept good hydrophobicity after 7~9 years' service. Microstructure changes of the silicone rubber insulators were respectively analyzed by infrared spectrum (IR), and energy dispersive spectroscopy (EDS). The IR results showed that service-aged silicone rubbers had main-chain fragmentation and methyl-group loss. The EDS results indicated that small organic silicon molecules (hydrophobic groups) moved to the surface of sheds and improved the hydrophobicity. Therefore, even though the surface microstructure of silicone rubber insulators changed in service, silicone rubber insulators still can keep good hydrophobicity because of the migration of small organic silicon molecules.