Accelerated aging investigation of high voltage EPDM/silica composite insulators

Abstract

Abstract Ethylene-propylene-diene-monomer (EPDM) is one of the most frequently used outdoor insulating materials. Like other polymeric materials, EPDM and its composites also degrade in outdoor applications. For evaluation of aging of insulating materials, accelerated multistress aging/weathering is an efficient method. In the current paper, comparative multistress aging performance investigation of neat EPDM (NE), EPDM with 20% microsilica (microcomposite, EMC), EPDM with 5% nanosilica (nanocomposite, ENC) and EPDM 20% microsilica 5% nanosilica (hybrid composite, EHC) is presented. Materials prepared according to ASTM D3182-07 were subjected to uniform ultraviolet (UV) radiation, heat, humidity, salt fog and acid rain at 2.5 kV voltage for 5000 h in a specially fabricated weathering chamber. For timely analysis of the aged materials, Fourier transform infrared (FTIR) spectroscopy, Swedish Transmission Research Institute (STRI) hydrophobicity classification and scanning electron microscopy (SEM) were used along with the critical visual inspection. Increasing discoloration was found in all materials which was proportional to% wt of the filler in composites. Improved hydrophobicity and better surface smoothness was recorded in composites as compared to NE, which was higher in the case of the microcomposite and hybrid composite. FTIR results showed least reduction in hydrocarbon bonds and lowest variation in chalking index in the case of the microcomposite.