Abstract
Thermally and mechanically enhanced nanoporous silica-polyurethane hybrid aerogel was synthesized by sol-gel processing and low temperature supercritical CO2 drying. A partially condensed silica solution and a polymeric MDI were used as the raw materials with a tertiary amine as a catalyst and 1,4-dioxiane as a dilution solvent. After the gelation reaction was completed, aged wet hybrid aerogel was dried by a low temperature supercritical CO2 drying technique. Also, thermophysical characteristics such as density, BET surface area, and thermal conductivity as a function of catalyst ratio and aging time of the synthesized hybrid aerogel were analyzed. It was found that, at a fixed target density, the lowest average pore size of the aerogel, 8 nm, was obtained when the catalyst ratio was 0.1 wt.%. Also, at these conditions, the BET surface area showed the highest surface area, 287.3 m2/g. It was found that with decreasing average pore size and with increasing BET surface area, thermal conductivity tends to decrease. At pressure 1 torr, the sample aerogel showed the lowest thermal conductivity, 0.0184 W/mK.
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References
Biesmans, G., Randall, D., Francais, E. and Perrut, M., “Polyurethane-based Organic Aerogels Thermal Performance,”J. Non-Cryst. Solids,225, 36 (1998).
Brinker, C. J., Draining, D. W. and Scherer, G. W., “A Comparison Between the Densification Kinetics of Colloidal and Polymeric Silica Gels,” Better Ceramics Through Chemistry I, Brinker, C. J., Clark, D. E. and Ulrich, D. R., eds., North-Holland, New York (1984).
Brinker, C. J. and Scherer, G. W., “Sol-Gel Science,” Academic Press Inc., Boston (1990).
Carslaw, H. S. and Jaeger, J. C., “Conduction of Heat in Solids,” 2nd ed., Chap. 10, Oxford University Press, London (1959).
Grazzini, G., Balocco, C. and Lucia, U., “Measuring Properties with Parallel Wire Method,”Int. J. Heat Mass Transfer,39(10), 2009 (1996).
Hrubesh, L. W., “Aerogel Applications,”J. Non-Cryst. Solids,225, 335 (1998).
Her, R K., “Chemistry of Silica,” John Wiley & Sons, New York (1978).
Kim, S. Y., Yeo, D. H., Lim, J. W., Yoo, K.-P., Lee, K. H. and Kim, H. Y., “Synthesis and Characterization of Resorcinol-Formaldehyde Organic Aerogel,”J. Chem. Eng. Jpn,34, 216 (2001).
Kistler, S. S., “Coherent Expanded Aerogels and Jellies,”Nature,127, 741(1931).
Lee, K.-H., Kim, S.-Y. and Yoo, K.-P., “Low-density, Hybrophobic Aerogels,”J. Non-Cryst. Solids,186, 18 (1995).
Schwertfeger, F., Glaubitt, W. and Schubert, U., “Hydrophobic Aerogels from Si(OMe)4/MeSi(OMe)3 Mixtures,”J. Non-Cryst. Solids,145, 85 (1992).
Tillotson, T. M. and Hrubesh, L. W., “Transparent Ultralow-density Silica Aerogels Prepared by a Two-step Sol-gel Process,”J. Non-Cryst. Solids,145, 44 (1992).
Tillotson, T. M., Hrubesh L. W. and Thomas, I. M., “Partially Hydrolyzed Alkoxysilanes as Precursors for Silica Aerogels,” Better Ceramics Through Chemistry III, Brinker, C. J., Clark, D. E. and Ulrich, D. R., eds., MRS, Pittsburgh (1988).
Tewari, P. H. and Arlon, J. H., “Process for Forming Transparent Aerogel Insulating Arrays,” US Patent 4610863 (1986).
Tewari, P. H., Hunt, A. J. and Loffuts, K. D., “Advance in Production of Transparent Silica Aerogels for Window Glazing,” Proceedings of the 1 International Symposium on Aerogels, Wurzburg (1985).
Woods, G., “The ICI Polyurethanes Book,” 2nd ed., ICI Polyurethanes (1990).
Yokogawa, H. and Yokoyama, M., “Hydrophobic Silica Aerogels,”J. Non-Cryst. Solids,186, 23 (1995).
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Yim, TJ., Kim, S.Y. & Yoo, KP. Fabrication and thermophysical characterization of nano-porous silica-polyurethane hybrid aerogel by sol-gel processing and supercritical solvent drying technique. Korean J. Chem. Eng. 19, 159–166 (2002). https://doi.org/10.1007/BF02706890
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DOI: https://doi.org/10.1007/BF02706890