from the conferences organized by TANGER Ltd. provisional website
Silica aerogels, as well as those consisting of other metal oxides (alumina, zirconia, titania or mixture of these oxides), are extremely porous (up to 99%) high-tech materials with very high specific surface areas (1000 m2 g-1) and low thermal conductivity (below 0.02 W / mK). The typical aerogel production process includes several steps and starts with the preparation of a sol. The next step includes a casting of the sol to obtain the required gel form via sol – gel transition and its drying in a supercritical drying chamber at supercritical conditions of CO2 to obtain the desired product. Hence, it is of critical importance to determine how processing parameters (type of solvent, catalyst, surfactant, a medium of drying, temperature, pressure, the presence of rheological agents (RA)) influence the microstructure, morphology, transparency and other properties of the obtained aerogels.In this work, we studied the effect on three synthesized systems: SiO2-Triton, SiO2-PVP and SiO2-F127 using TMOS, MeOH-NH4OH-H2O at constant molar ratios of reactants 1:7:0.7:2.7, respectively. Chemical, structural and morphological results were performed by using FTIR and SEM techniques. SEM imaging analysis demonstrated a change in agglomerate size distribution (5-10 nm) depending on the system. Furthermore, the increase in the amount of F217 agent increased both the density, measured by sample dimensions, of produced SiO2-F127 aerogels from 0.09 to 0.2 g·cm-3 along with the pore size.Keywords: Aerogel, Supercritical drying, surfactant, porosity
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