Investigation of Binary Liquids in Unstable States—An Experimental Approach

Abstract

In this article, we present a methodology for conducting measurements based on pulse heating of a wire probe in partially soluble binary liquids. These liquids, which can be rapidly transferred to the region of unstable states above the diffusional spinodal, are novel research objects for the thermophysics of extreme states. Using the example of aqueous solutions of polypropylene glycol and glycol monobutyl ether having a lower critical solution temperature, the key hypothesis of the study on the general measurability of the properties of unstable solutions has been confirmed. The characteristic heating times from 1 to 15 milliseconds corresponded to the thickness of the heated layer comprising a few micrometers. The pressure was varied from units of MPa to 100 MPa. The conditions for the transition from measurements on pure components to those on solutions are formulated. The characteristic thermal patterns of the decay of unstable states depending on pressure and heating rate are revealed. The general possibility of using partially soluble binary liquids as a promising coolant in processes involving powerful local heat release is demonstrated.

To the possibility of experimental estimation of the diffusion spinodal position of binary mixture with LCST via pulsed heating method

“…The aim of this work was to calculate the position of the diffusion spinodal of a water/PPG-425 mixture in the framework of the Flory-Huggins approximation and to develop an experimental technique for estimating the position of the spinodal of two-component mixtures with LCST based on the method of controlled pulsed heating of a wire probe -a resistance thermometer. This method has a number of characteristic advantages: the ability to control and change the heating parameters on a microsecond temporal scale, access to the primary experimental data obtained in the course of heating, and a wide range of temperatures and pressures (up to 800 o C and 100 MPa) available for the research [10].…”