Effective preparation of crack-free silica aerogels via ambient drying |
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Authors: | Sung-Woo Hwang Hae-Hyun Jung Sang-Hoon Hyun Young-Soo Ahn |
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Affiliation: | (1) School of Advanced Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-Gu, Seoul, 120-749, Korea;(2) korea Institute of Energy Research, Daejeon, 62-1, Korea |
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Abstract: | Effective ambient-drying techniques for synthesizing crack-free silica aerogel bulks from the industrial waterglass have been developed. Silica wet gels were obtained from aqueous colloidal silica sols prepared by ion-exchange of waterglass solution (4–10 wt% SiO2). Crack-free monolithic silica aerogel disks (diameter of 22 mm and thickness of 7 mm) were produced via solvent exchange/surface modification of the wet gels using isopropanol/trimethylchlorosilane/n-Hexane solution, followed by ambient drying. The effects of the silica content in sol and the molar ratio of trimethylchlorosilane/pore water on the morphology and property of final aerogel products were also investigated. The porosity, density, and specific surface area of silica aerogels were in the range of 92–94%, 0.13–0.16 g/cm3, and ∼675 m2/g, respectively. The degree of springback during the ambient drying processing of modified silica gels was 94%. |
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Keywords: | Aerogel Silica Surface modification Ambient drying |
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