Phase Behavior of Polymer Solutions from Macroscopic Properties: Application to the Perturbed Chain Statistical Associating Fluid Theory Equation of State

Abstract

In this work, a parametrization strategy that allows the estimation of polymer molecular parameters from a predefined set of macroscopic properties is presented. The parametrization scheme has been developed in terms of the polymer−solvent interaction parameter (χ) and the Hildebrand parameter, which are readily available in the literature for a large variety of solvents and polymers. In this way neither extensive experimental data nor complex optimization schemes are necessary. The proposed parametrization strategy is demonstrated by reference to the PC-SAFT equation of state, but can be applied to any molecular-based model. The polymers investigated in this study include polyisobutylene, polyethylene, polypropylene, and polystyrene as well as polybutadiene, polyisoprene, and polybutene, which were used to investigate the predictive capacity of the parametrization strategy presented in this work. The solvents studied include nonassociating compounds such as n-alkanes, polar compounds such as ethers, esters, and ketones, and associating compounds such as alcohols. Phase equilibria calculations of binary and ternary polymer solutions are made to evaluate the performance of the PC-SAFT model using polymer molecular parameters calculated from the proposed parametrization strategy. The results obtained are in agreement with the available experimental data for most studied systems, demonstrating the reliability of the parametrization scheme developed in this work.