Closed‐Loops of liquid‐liquid immiscibility in binary mixtures of equal sized molecules predicted with a simple theoretical equation of state

Abstract

AbstractSeveral types of closed‐loop liquid‐liquid immiscibility behavior in binary mixtures have been found with a simple isotropic model fluid. The calculations are based on an equation of state composed by the Carnahan‐Starling hard sphere repulsion and the van der Waals‐attraction. The extension to binary mixtures is accomplished with the usual quadratic one‐fluid mixing rules. The results are presented in a global phase diagram as introduced by van Konynenburg and Scott. Several closed‐loop phase diagrams similar to those discovered by Boshkov ten years ago with a Lennard‐Jones equation of state have been found. The results are discussed in the context of the topological and physical origin of closed‐loop behavior in systems of isotropic mixtures.