Application of the sCPA equation of state for polymer solutions

Specific interactions, for example hydrogen bonding, dominate in numerous i ndustrially important polymeric systems, both polymer solutions and blends. Typical cases are water-soluble polymers including biopolymers of special interest to biotechnology (e.g. the system polyetfiyleneglycol/dextran/wate r). Furthermore, most polymer blends are non-compatible and the requirement for compatible polymer pairs is often the presence of hydrogen-bonding int eractions (e.g. polyvinylchloride/chlorinated polyethylene). In this work w e give at first a short, comparative evaluation of existing thermodynamic m odels suitable for polymeric systems that take into account, explicitly, sp ecific interactions Like HE. The range of application of the models in term s of phase equilibria and their specific characteristics (accuracy of calcu lation, degree of complexity) are discussed. Finally, vapor-liquid equilibr ia (VLE) calculations for a number of polymer + solvent systems (including five different polymers) with a novel and very promising model are presente d. This model is in the form of an equation of state that is (in its genera l formulation) non-cubic with respect to volume and has separate terms for physical and chemical interactions. The model has recently been proposed an d has already been successfully applied to (alcohol/water/hydrocarbons). Th is is the first time that it is extended to polymer solutions. (C) 2000 Els evier Science Ltd. All rights reserved.