(309a) Saft-D: a New Equation of State for Polymeric Fluids

To design and optimize chemical products and processes, scientists and engineers need computational tools to predict bulk and interfacial properties of complex fluids in terms of temperature, pressure, composition, and molecular geometry. Typical examples of complex fluids include polymer blends and solutions, surfactants, emulsions, polar and associating fluids, as well as aqueous systems. The phase behavior of polymer solutions depends on the polymer molecular weight, chain branching, branching density, and on the presence of polar or associating groups in the chain. Knowledge of the phase behavior of polymer solutions is of great importance at several stages of polymer synthesis and processing.

The Dimer chain term proposed by Ghonasgi and Chapman (J. Chem. Phys. 1994, 100, 6633-6639, accounting 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 for chain fluids. The new equation of state is applied to the homologous series of n-alkanes, as well as to polymers. The predictive and extrapolative capabilities of the model are demonstrated through comparisons with experimental data for pure component and mixtures, and the performance of the model is discussed vis-à-vis some of the existing approaches. The new equation of state provides an accurate description of liquid densities over the whole range of temperature, including the critical region. The predictions for binary mixtures are in excellent agreement with experimental data, and the description of the phase behavior of polymer solutions is improved as compared to PC-SAFT predictions, especially at high polymer concentration.