Structural-mechanical properties of micelle-forming surfactants in the liquid crystal stateстатья
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Дата последнего поиска статьи во внешних источниках: 12 октября 2013 г.
Аннотация:In aqueous media the typical micelle-forming stabilizers of disperse systems (fatty acid soaps C-12-C-18 with different hydrophilicity) can form lyophilic disperse structures. The mechanism of this process at high supersaturations has been studied. The results on solubility of the soaps in water at different temperatures, on gel formation, on rheological and structural-mechanical properties of these systems indicate that soaps with a double bond in the molecule (sodium and ammonium oleates) exist in micellar and in liquid crystal state; over a wide range of concentrations their behaviour is both visco-elastic and plastic. Saturated soaps crystallize from supersaturated micellar solutions to form quasi-solid disperse structures completely immobilizing the dispersion medium. Strain behaviour and strength of these systems have been studied in the range of surfactant concentrations from 0.5x10(-2) to 20x10(-2) kg/kg at 5-60 degrees C and the equal strength cross-sections of three-dimensional strength diagrams have been examined in terms of solubility and gel formation curves. The results were used for quantative analysis of formation and development of three-dimensional structures in the systems. It is shown that below the Kraft point the strength of the systems studied is temperature-independent. In this view one may perform reliable strength measurements not influenced by temperature.