A perturbed hard-sphere-chain equation of state for polymer solutions and blends based on the square-well coordination number model

Based on the concept of a perturbed hard-sphere-chain (PHSC), where the squ are-well fluid is the reference system, a perturbation term is developed fr om the coordination number model for prise and mixture square-well fluids p roposed by this group. Consequently, we derive a new PHSC type equation of state (EOS), which is of much simpler formulation and is even easier to use . The EOS has been extensively tested in terms of a large data bank, consis ting of the properties of 37 normal fluids and solvents, 67 polymers. The c orrelation accuracy for the saturated properties is within the errors in co mmon EOS approach. In particular, the grand average deviation for correlati ng the liquid densities for 67 polymers is 0.19%, which is of the same accu racy as that for commonly used lattice model EOSs. In all of the calculatio ns, the EOS needs only three temperature- and composition-independent param eters. In addition, the new EOS is used for 40 sets of vapor-liquid equilib rium (VLE) calculations of polymer-solvent systems. Three typical liquid-li quid equilibrium (LLE) systems have been investigated by using the EOS, inc luding both the upper critical solution temperature and the lower critical solution temperature polymer-solvent and polymer blend systems. The calcula ted binodal and spinodal curves are in good agreement with experimental dat a. All of the VLE and LLE calculations need conventional mixing rules and o nly a binary interaction parameter.