The global phase behaviour of binary mixtures of chain molecules: theory and application

Abstract

In this work the global phase behaviour of binary fluid mixtures of chain molecules is investigated. The underlying model employed for the investigation is based on our recently developed equation of state for chain molecules. This equation is based on the statistical associating fluid theory for chains of attractive hard spheres. It is an optimized equation of state for chain molecules which can be rearranged into a fourth order polynom in the molar volume. With this equation of state the global phase diagram for several mixtures of spherical molecules with non-spherical molecules has been investigated. The non-spherical molecules range from small non-spherical over short chain molecules to long chain polymer molecules. Special attention is paid to mixtures of small spherical molecules with long chain molecules. Such mixtures are employed to model polymer–solvent mixtures. Based on the calculated global phase diagram for polymer solutions, several processes such as co- or anti-solvent processes and polymerisations are discussed. These processes are represented by paths in the global phase diagram.