Category: Transient Plane Source
Author(s): Ai Du, Bin Zhou, Guangming Wu, Guangwu Liu, Guoqing Zu, Jun Shen, Xing Yuan Ni, Xingyuan Ni
Keywords: Apparent Density, BET Method, Brunauer-Emmett-Teller, Brunauer-Emmett-Teller (BET), differential scanning calorimetry, Differential scanning calorimetry (DSC), DSC, Fourier transform infrared spectroscopy (FTIR), Fourier-Transform Infrared Spectroscopy, FTIR, Pore Size Distribution, Pore Size Distribution (PSD), porosity, PSD, Scanning Electron Microscopy, Scanning Electron Microscopy (SEM), SEM, Silica aerogels, specific surface area, TGA, Thermal Conductivity, thermal insulation, Thermo Gravimetric Analyzer, Thermo Gravimetric Analyzer (TGA), Transient Plane Heat Source Method
Abstract: Ambient pressure dried hydrophobic silica aerogel monoliths were prepared via simultaneous solvent exchange and surface modification in order to minimize volume shrinkage and density. At room temperature, the obtained silica aerogels had a low density of 0.096 g/cm3, a high surface area and hydrophobicity, and a low thermal conductivity of 0.0217 W/m·K. The effect of heating on these properties was also determined. After the aerogel had been heated to 300oC, it was still hydrophobic, and the density had decreased to 0.094 g/cm3. At 800oC, thedensity was increased to 0.113 g/cm3. The thermal conductivity of the aerogel increased from 0.0217 W/m·K at room temperature up to 0.0981 W/m·K at 800oC; however, since this thermal conductivity is still very low, it was concluded that these aerogels are still excellent thermal insulators at high temperature.
Reference: Journal of Sol-Gel Science and Technology, 62, 2 (2012) 126-133