Reducing the flammability of hydrophobic silica aerogels by tailored heat treatment

In this study, tailored heat treatment was employed to lower the flammability of hydrophobic silica aerogels (HSA). The effects of heat treatment temperature, time, and heating rate on the pore structure and flammability of the treated SA were investigated in detail. It was revealed that the heat-treated HSA still maintained a mesoporous structure with a lower tap density and a higher specific surface area. The chemical groups of the treated HSA were influenced significantly by the heat treatment temperature but were independent of the heat treatment time and heating rate. Due to the removal of organic groups, the flammability of the heat-treated SA was reduced significantly. Hence, it was demonstrated that reducing the flammability of HSA by tailored heat treatment was feasible, which can provide a simple approach to reduce the flammability of SA and benefited their expansion in thermal insulation field.