Synthesis of silica cryogel-glass fiber blanket by vacuum drying

Silica cryogel-glass fiber composites with a high specific surface area and high mesoporosity were fabricated via a simple still original drying technique. By applying vacuum at ambient temperature, the system evolution has been monitored and represented in the water phase diagram. The ratio of solvent/silica loading significantly affected the porous structure and thermal insulating properties of the blanket. From the results of BET surface area, apparent density and porosity studies, the microstructures and specific surface areas of the composites were greatly affected by changing the silica amount in the sol. The microstructure of silica cryogel blanket exhibits a porous structure consisting of glass fibers of diameter ~7 μm interconnected with solid silica clusters (5-20 μm). Silica cryogel-glass fiber blankets with low densities from 0.13-0.24 g/cm3 and thermal conductivity as low as 0.02-0.035 W/mK were obtained using this cost effective, hazardous free and time saving method. The pH of the silica sol influenced the gelling property and the thermal conductivity of the composites.