Peculiarities of phase transformations in aqueous isopropanol solutions

Abstract

Peculiarities of phase transformations in aqueous isopropanol solutions are studied in the range from room temperature to −15°C. It is found that solution cooling results in the formation of macroaggregates with regular geometrical shapes, which are dispersed in the liquid phase and directedly move in the field of a temperature gradient. In aqueous isopropanol solutions with concentrations of 10–30 vol %, the aggregates are formed at temperatures of −10 to −15°C. The average aggregate size is several millimeters. Under the action of a temperature gradient, the aggregates move to the region of higher temperatures. At temperature gradients of 1–2 K/cm, the aggregate velocity is 1–2 mm/s. The characters of the motion and interaction of aggregates are very sensitive to the temperature distribution in a solution. After the aggregate motion ceases, crystallization of the liquid phase that initially is outside of the aggregates is observed.