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G. D. Nipan, O. A. Mykaylo*,**, and Young-Jei Oh**
«The Selection of Azeotropes at Ambient Pressure Drying of Aerogels.»
PACS numbers: 05.70.Ce, 64.60.F-, 64.75.Cd, 64.75.Jk, 81.05.Rm, 81.30.Dz, 82.70.Gg
The representation of phase states in the multicomponent systems by graphical images is used for estimation of the LV (xL???xV) azeotrope influence on SLV and L???V equilibria. These theoretical investigations occurred from complications arising at an ambient pressure drying (APD) synthesis of transparent and crack-free bulk silica aerogels. During the empiric selection of azeotropic mixtures, the negative azeotropes advantage over positive ones for this goal is determined and substantiated in theory. As shown, the forecast must base not only on the critical points of components (L???V), in which liquid and vapour become indistinguishable, but also on the triple points of components (SLV—crystal–liquid–vapour). Using the P–T–x phase diagrams, the prediction of ways to reach a supercritical region at the ambient pressure is done. A good agreement between the theoretical results and experimental data is revealed.