Relationship analysis of processing parameters with micro and macro structure of silica aerogel dried at ambient pressure

In the present study, tetraethoxysilane (TEOS) aerogel was produced by a two-step catalytic process at ambient pressure drying under different synthesis conditions. The relationship of the key processing parameters such as EtOH/TEOS, H2O/EtOH molar ratios and synthesis temperature with micro and macro structures of the synthesized aerogel has been analyzed. The effectiveness degree of each key processing parameter in the microstructure and then the effects of microstructure changes on the morphology and physical properties including the density and porosity were also evaluated. The results apparently showed that the processing temperature presented the highest effectiveness on the pore structure, porosity and density of the synthesized aerogels. Synthesizing at the temperature of 30 degrees C gave rise to a dense structure with very small pore size (3 nm) and porosity of 59% which exhibited a type-I adsorption-desorption isotherm. Other processing parameters affected the micro and macro structure but their effects were less significant compared to the temperature effect. (C) 2013 Elsevier B.V. All rights reserved.