ABSTRACT Peculiar xerogels and aerogels constituted by a silica network, made of spherical fully dense silica particles having the same size, are investigated by adsorption of nitrogen at 77.4 K. Comparison of sorption data between materials dried via different methods, gentle drying at room temperature, alcohol supercritical drying and CO2 supercritical drying, shows that the specific surface area is associated to the particle sizes and necks established between them during drying and not to the sample density. The dissolution-redeposition of silica, which occurs in the alcohol supercritical drying process, induces a decrease of specific surface area and consequently an increase in the mechanical properties comparatively to CO2 supercritical drying. Investigating pore volume measurements as a function of dwell time, which is the interval of time allowing a pressure change of 0.01%, we corroborate that for compliant materials the full volume can not be detected because of capillary stresses. So the time required to perform correct measurements of the pore volume decreases with sample bulk density increase and elastic properties increase. All these experiments qualitatively corroborate the theory proposed previously.
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H. Satha, K. Atamnia and F. Despetis, "Effect of Drying Processes on the Texture of Silica Gels," Journal of Biomaterials and Nanobiotechnology, Vol. 4 No. 1, 2013, pp. 17-21. doi: 10.4236/jbnb.2013.41003.
 R. K. Iler, “The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface Properties, and Biochemistry,” Wiley, New York, 1979.
 C. J. Brinker and G. W. Scherer, “Sol-Gel Science: The Physics and Chemistry of Sol-Gel Processing,” Academic Press, Inc, 1990.
 J. Fricke, “SiO2-Aerogels: Modifications and Applications,” Journal of Non-Crystalline Solids, Vol. 121, No. 1-3, 1990, pp. 188-192.
 G. W. Scherer, “Recent Progress in Drying of Gels,” Journal of Non-Crystalline Solids, Vol. 147-148, 1992, pp. 363-374.
 G. W. Scherer, S. Calas and R. Sempere, “Sintering Aerogels,” Journal of Sol-Gel Science and Technology, Vol. 13, No. 1-3, 1998, pp. 937-943.
 H. Satha, A. Haddad and J. Phalippou, “Silica Glass from Aerosil by Sol-Gel Process: Densification and Textural Properties,” International Journal of Thermophysics, Vol. 24, No. 3, 2003, pp. 885-893.
 S. Brunauer, P. H. Emmet and E. Teller, “Adsorption of Gases in Multimolecular Layers,” Journal of the American Ceramic Society, Vol. 60, No. 2, 1938, pp. 309-319.
 E. P. Barret, L. G. Joyner and P. P. Halenda, “The Determination of Pore Volume and Area Distributions in Porous Substances,” Journal of the American Ceramic Society, Vol. 73, No. 1951, pp. 373-380.
 G. Reichenauer and G. W. Scherer, “Nitrogen Sorption in Aerogels,”Journal of Non-Crystalline Solids, Vol. 285, No. 1-3, 2001, pp. 167-174.
 M. Foret, J. Pelous and R. Vacher, “An Investigation of the Structure of Colloidal Aerogels,” Journal of Non-Crystalline Solids, Vol. 147-148, 1992, pp. 382-385.
 J. Zarzycki, “Structure of Dense Gels,” Journal of Non-Crystalline Solids, Vol. 147-148, 1992, pp. 176-182.
 M. Pauthe, “Gels de Silice Issus de Composés Organométalliques Modifiés. Leur Applications aux Verres d’Oxynitrure de Silicium,” Ph.D. Thesis, Montpellier University, Montpellier, 1989.
 T. Woignier, J. Phalippou, J. F. Quinson, M. Pauthe and F. Laveissiere, “Physicochemical Transformation of Silica Gels During Hypercritical Drying,”Journal of Non-Crystalline Solids, Vol. 145, 1992, pp. 25-32.
 S. Sakka, “Handbook of Sol-Gel Science and Technology: Characterization and Properties of Sol-Gel Materials and Products,” Springer, New York, 2005.