Thermal Characteristics of Various Silicone Rubber Composites Filled with Silica

Thermal conductivity enhanced by the addition of inorganic fillers such as, natural silica has been shown as critical factor improving the erosion performance of silicone rubber filled with micro-sized silica in the inclined plane tracking and erosion test (IPT). In this research, different thermal characteristics of SiR composites filled at 50 w% with natural silica of different median particle sizes (2, 5 and 10 µm) are investigated in both the condensed and gas phases. The thermal conductivity was shown to decrease from 0.5905 W/m.K with 10 µm silica to 0.5230 W/m.K with 2 µm silica, despite the interaction promoted between the 2 µm silica and the polymer. Accordingly, the improvement in the thermal conductivity of SiR by the addition of micro-sized natural silica was elucidated from different perspective than the filler-SiR interaction. The suppression of depolymerization was more evident with 2 µm silica due to the enhanced interaction between the filler and the polymer as indicated by the thermogravimetric and differential thermal analyses.