Ethylene-bridged polysilsesquioxane/hollow silica particle hybrid film for thermal insulation material

Abstract

Ethylene-bridged polysilsesquioxane (EBPSQ) was prepared by the sol–gel reaction of bis(triethoxysilyl)ethane. The whitish slurry was prepared by mixing EBPSQ and hollow silica particles (HSPs) with a median diameter of 18–65 μm at 80 °C, and it formed a hybrid film by heating at 80 and 120 °C for 1 h at each temperature, then at 200 °C for 20 min. The surface temperatures of EBPSQ films containing 10 wt% and 20 wt% of HSPs (90.2 °C–90.5 °C) were lower than those of EBPSQ films (93.6 °C), when the films on the duralumin plate were heated at 100 °C for 10 min from the bottom of the duralumin plate. The thermal conductivity/heat flux (k/q) obtained from the temperature difference between the surface temperature and bottom temperature of the films and the film thickness also decreased with adding the HSPs. EBPSQ film without HSPs exhibited T⁵_d of 258 °C and T¹⁰_d of 275 °C. However, EBPSQ film containing 20 wt% of HSPs exhibited high thermal stability, and T⁵_d and T¹⁰_d were 299 °C and 315 °C, respectively. Interestingly, T⁵_d and T¹⁰_d of the hybrid films increased with an increase in the number of HSPs. Overall, it was shown that HSPs could improve the thermal insulation properties and thermal stability.