Influence of Nano Sized Fillers on Suppressing DC Erosion of Hybrid Silicone Rubber Composites

This paper investigates the influence of nano sized alumina trihydrate and fumed silica fillers on suppressing the DC erosion of hybrid silicone rubber composites containing micron-sized alumina trihydrate filler. Fumed silica was found to be more influential on enhancing the thermal conductivity of the composites compared to nano alumina trihydrate, which is possibly a result of the better filler dispersion of the former. Thermogravimetric analysis suggests the effectiveness of fumed silica in suppressing depolymerization of silicone rubber as a result of silica's favourable interaction with the silicone polymer. Furthermore, the thermal analyses outcomes indicate a significant absorbed moisture content in nano alumina trihydrate which could have adversely impacting the residue characteristics and poorly suppressed silicone rubber depolymerization. In addition, a high temperature endotherm for micro sized alumina trihydrate filler was found indicating the possible decomposition of boehmite to release water molecules promoting the internal oxidation of silicone rubber at high temperature. Outcomes of the +DC inclined plane tracking erosion test correlate with those of the thermal analyses indicating a more influential role for fumed silica's interface in enhancing the DC erosion performance of silicone rubber despite the silica hybrid composite having a lower thermal conductivity than micro alumina trihydrate filled silicone rubber.