New equation of state for polymer solutions based on the statistical associating fluid theory (SAFT)-Dimer equation for hard-chain molecules

The dimer-chain term proposed by Ghonasgi and Chapman [J. Chem. Phys. 1994, 100, 6633-6639], which accounts for the chain connectivity, is used in conjunction with the perturbed-chain dispersion term proposed by Gross and Sadowski [Ind. Eng. Chem. Res. 2001, 40, 1244-1260] to form a new equation of state (EOS) for polyatomic fluids. The new EOS is applied to the homologous series of n-alkanes, mixtures of long- and short-chain alkanes, and polymers. The predictive and extrapolative capabilities of the model are demonstrated through comparisons with experimental data for pure components and mixtures. The new EOS provides an accurate description of liquid densities over the entire range of temperature, including the critical region. The predictions for mixtures of long- and short-chain alkanes are in excellent agreement with experimental data without using a binary interaction parameter. The description of the phase behavior of polymer solutions is improved, in comparison to perturbed-chain-statistical associating fluid theory (PC-SAFT) predictions, especially at high polymer concentrations.