Change in Heat Resistive, Electrical Insulating and Mechanical Properties of Hybrid Made with PDMS and TEOS for the Mole Ratio of Them

Heat resistive, electrical insulating and mechanical properties of hybrids made with polydimethylsiloxane (PDMS) and tetraethoxysilane (TEOS) through the sol-gel reaction method have been studied by changing the mole ratio of TEOS to PDMS. It has been found that the weight loss of the hybrids is less than 3 % regardless of the mole ratio after ageing at 200 degC for 480 h in air. The expected weight loss of the hybrids after ageing for 20,000 h at 200 degC is less than 7 %. It has been found that the elastic modulus and the stress at break of the hybrids increases with increasing the mole ratio. Those mechanical properties are improved after the ageing because of further dehydration and condensation polymerization reactions through the ageing. The volume resistivity decreases and the dielectric loss tangent increases with increasing the mole ratio. Even at the mole ratio of 10, the resistivity is in the order of 1013 ohm-m at room temperature. Relative permittivity and AC dielectric breakdown strength of the hybrids are about 3 and 25 kV/mm. respectively. After the ageing, increases of volume resistivity, relative permittivity and a decrease of dielectric loss tangent of the hybrids have been observed and AC breakdown strength of them shows little change. It has been concluded that the hybrid made with TEOS and PDMS has the potential of a higher heat resistive insulating material.