Hydrophobic, dielectric and water immersion performance of 9000 h multi-stresses aged silicone rubber composites for high voltage outdoor insulation

Abstract

Room temperature vulcanized silicone rubber (RTV-SiR) materials are broadly employed for high voltage outdoor insulation applications. Like other polymeric materials, such insulators degrade due to the multiple stresses caused by the environment. Therefore, for the investigation of multiple stresses presented in the environment such as UV radiations, salt fog, acid rain, heat, humidity, etc., a neat SiR, two aluminum trihydrate (ATH) filled composites of SiR (SMC1 and SMC2), one silica filled composite SiR (SMC3), and a co-filled composite (SMNC) having ATH and silica as fillers are fabricated and tested for 9000 h. After aging, the sample SMC3 and neat SiR show better hydrophobic behavior than the other samples. All the samples offer better leakage current suppression throughout aging. Dielectric breakdown strength (DBS) of SMC2 and SMC1 is measured better than their counterparts. Volume and surface resistivities of SMC1 remain the highest followed by SMC2 and SMC3. Scanning electron microscopy (SEM) results suggest that the surface of SMC2 retains excellent surface condition followed by neat SiR. SMC1, SMC2, and SMNC absorb higher water relatively after 24 h of immersion test whilst SMC1 and SMC3 exhibit a similar tendency after 2-h boiling test.