Water immersion/liquid permeation resistance analysis of micro/nano-SiO2 filled silicone rubber and epoxy composites for high voltage insulation applications

In recent years, compared to the porcelain and glass insulators, the silicone rubber (SiR) and epoxy based polymer composite insulators have been widely investigated for high voltage (HV) insulations, due to its promising electrical, physical, and chemical properties. Multiple environmental entities such as humidity, ultraviolet (UV) radiation, aqueous solutions/moisture, micro-organisms, natural contaminations etc., generally degrade the long-term performance of polymer insulants. In the scope of this work, we have studied the influence of micro and nano sized silica (SiO
₂
) fillers on water immersion/permeation resistance of room temperature vulcanized silicon rubber (RTV-SiR) and epoxy composites. Both RTV-SiR and epoxy based composite samples with varying concentration of SiÜ2 particles were developed by following the standard procedure (ASTM-D1418-10a). In order to investigate the comparative immersion/permeation resistance of SiR and epoxy blends, the 24h immersion tests and 02h boiling water immersion tests were performed using ASTM-D570 standard procedure. Results of 24h immersion tests indicated that micro-SiO
₂
blend with epoxy (15%μSiO
₂
+ epoxy) showed comparatively higher immersion resistance i.e. minimum mass uptake of ~10mg (0.092%). The 02h boiling water tests revealed that neat epoxy samples loosed its mass of -110 mg (-1.14%). The immersion/permeation reports suggest that the liquid permeation and immersion resistance of polymer blends is governed by particle size, type, and weight percent (wt. %).