Effects of Ph12SQ on the thermal stability and mechanical properties of high temperature vulcanized (HTV) silicone rubber

Ph
₁₂
SQ (C
₆
H
₅
SiO
_1.5
)
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 Ph
₁₂
SQ 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 T
_d1%
is delayed from approximately 215 °C for DD
₀
to 350 °C (DD
₂₀
) (about 130°C) and the T
_d5%
mass loss exhibits a similar trend. The thermo-oxidative stability also increases with Ph
₁₂
SQ 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 Ph
₁₂
SQ to 5 wt% (DD
₅
). Moreover, the addition of Ph
₁₂
SQ 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 T
_d5%
at different heating rates were applied for comparison of the lifetime of DD
₀
and DD
₅
samples according to the D&R model. The results show that DD5 offers a longer lifetime than DD
₀
at different temperatures.