IInterfacial Behavior in Type IV Systems

Type IV mixtures exhibit two heteroazeotropic lines, one at low temperature and the other meeting the supercritical range, characterized by the proximity of their critical end points (CEPs). Between these CEPs, the liquid phase is homogeneous inside a narrow range of temperature. The aim of this work is to analyze iInterface properties and wetting transitions for Type IV mixtures. IInterfacial tensions have been calculated by means of the gradient theory, applied to binary van der Waals fluids. This approach is able to predict iInterfacial tension and phase equilibrium using a common equation of state (EOS). Results show that iInterfacial properties and wetting conditions are governed by the densities and the number of phases involved in equilibrium, a scenario that changes as temperature evolves from the low- to the high-temperature heteroazeotropic line.