Effects of Ph12SQ on the Thermal Stability and Mechanical Properties of High Temperature Vulcanized (HTV) Silicone Rubber

Richard Laine

Mitra K Moghadam, Jalil Morshedian, Morteza Ehsani, Richard M Laine, Lim Y Kuang, and Noritsugu Umehara (2014)

Dielectrics and Electrical Insulation, IEEE Transactions on, 21(1):244-252.

Ph12SQ (C6H5SiO1.5)12 was blended into a polydimethylsiloxane (PDMS) based HTV silicone rubber as a reinforcing filler at loadings of (0, 2.5, 5, 10, 15, 20% by weight). The thermal stabilities and mechanical properties of these HTV silicone rubber composites were studied by thermal gravimetric analysis (TGA) and tensile testing, respectively. Dispersions of Ph12SQ were characterized by scanning electron microscopy (SEM). The obtained results show the presence of SQ-rich regions that affect the thermal stabilities and mechanical properties of HTV silicone rubber. TGA shows that Td1% is delayed from approximately 215 °C for DD0 to 350 °C (DD20) (about 130°C) and the Td5% mass loss exhibits a similar trend. The thermo-oxidative stability also increases with Ph12SQ weight fraction. Also, the tensile strength and elongation at break of these HTV silicone rubbers increase from 8.8 to 11 MPa and 655 to 950 % with incremental loading of Ph12SQ to 5 wt% (DD5). Moreover, the addition of Ph12SQ increases its relative permittivity from 3.2 to 14.2 and the dissipation factor at 1 MHz increases from 0.01 to 0.05. Finally, the values of Td5% at different heating rates were applied for comparison of the lifetime of DD0 and DD5 samples according to the D&R model. The results show that DD5 offers a longer lifetime than DD0 at different temperatures.

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