A Comparison between effect of fume silica and POSS (Ph12SQ) on HV Silicone rubber insulators lifetime
Hydrophilic and hydrophobic fume silica and Ph12SQ derivatives were blended into a polydimethylsiloxane (PDMS) based HTV silicone rubber as reinforcing filler at loading of 5 % by weight. The thermal stabilities were studied by thermal gravimetric analysis (TGA), respectively. The obtained results show the presence of these fillers-rich regions that affect the thermal stabilities of HTV silicone rubber. TGA shows that Td1% is delayed from approximately 260 °C for SR to 345, 335, 275 °C for P5, S5, DD5 (about 45, 35,15 °C) and the Td5% mass loss exhibits a similar trend. Finally, the values of Td5% at different heating rates were applied for comparison of the lifetime of SR, P5, S5 and DD5 samples according to Dobkowski-Rudnik (D&R) kinetic model. The results show that F5 offers a longer lifetime than SR at different temperatures.
The results showed that hydrophilic fume silica offers better improvements in thermal stabilities for HTV silicone rubbers compared to those obtained using hydrophobic fume silica and also Ph12SQ at 5 wt % loadings. These enhancements in thermal properties are ascribed to the effects of better polymer-particle interaction between hydrophilic fume silica and PDMS.