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Silica aerogels were synthesized via solvent exchange/surface modification of wet gels from waterglass using IPA/TMCS/n-Hexane solution. The densities, porosities, and specific surface areas of the aerogel were in the range of 0.128–0.153 g/cm3, 93–95%, and 598–795 m2/g, respectively. Aerogel-PVB composites were manufactured by hot pressing. Aerogels were crushed and mixed with PVB. Three mixing methods were performed. The aerogel-PVB composites had densities of 0.19–1.09 g/cm3, and thermal conductivities of 0.03–0.12 W/(m · K). Density and thermal conductivity can be controlled by aerogel volume fraction and the mixing method. The modulus of rupture of aerogel-PVB composites was in the range of 0.15–46.5 MPa.

A new modified ambient drying process for synthesizing silica aerogels cost-effectively from waterglass has been developed. Crack-free silica aerogels were obtained via solvent exchange/surface modification of wet gels using IPA/TMCS/n-Hexane solution. Silica aerogels were heated at different temperatures. The effects of heating temperature on chemical bonding state of aerogels were investigated by means of DTA and FTIR. The surface characteristic of the aerogel was hydrophobic when heat-treated under 350°C. The porosities, densities, and specific surface areas of the silica aerogels were in the range of 93–94%, 0.12–0.15 g/cm3, and ∼630 m2/g, respectively. Distinct spring back phenomena were observed in surface modified wet gels during drying.