Effect of Processing Temperature on Gelation and Physical Properties of Low Density TEOS Based Silica Aerogels |
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Authors: | Nagaraja D Hegde A Venkateswara Rao |
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Institution: | (1) Air Glass Laboratory, Department of Physics, Shivaji University, Kolhapur, 416 004, Maharashtra, India |
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Abstract: | In the present paper the experimental results of the effect of sol-gel processing temperature on the physical properties of
the TEOS based silica aerogels are reported and discussed. The aerogels were produced by the two step sol-gel process at various
temperatures in the range of 26–70∘;C followed by supercritical drying using methanol solvent extraction. A remarkable reduction in the gelation time was observed
from three and a half days at room temperature to a mere 18 hours at 50∘;C. The best quality aerogels in terms of low density and high optical transmission were obtained for 6 hours hydrolysis time.
The aerogels were characterized by the measurements of bulk density, volume shrinkage, porosity, refractive index and optical
transmission. Monolithic aerogels with ultra low density (∼0.018 g/cm3), extremely high porosity (∼99%) and optimum optical transmission at 700 nm (∼75%) were obtained for the molar ratio of TEOS:MeOH:acidic
water:basic water at 1:99:10.42:14.58 respectively. |
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Keywords: | Aerogels porous materials transmission electron microscopy (TEM) density and optical transmission |
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