A Modified Mixing Rule for PSRK Model and Application for the Prediction of Vapor-Liquid Equilibria of Polymer Solutions

摘要

To extend the PSRK (predictive Soave-Redlich-Kwong equation of state) model to vapor-liquid equilibria of polymer solutions, a new EOS-g~E mixing rule is applied in which the term Σ x_i ln(b/b_i) in the PSRK mixing rule for the parameter a, and the combinatorial part in the original universal functional activity coefficient (UNIFAC) model are cancelled. To take into account the free volume contribution to the excess Gibbs energy in polymer solution, a quadratic mixing rule for the cross co-volume b_(ij) with an exponent equals to 1/2 is applied [b_(ij)~(1/2) = 1/2(b_i~(1/2) + b_j~(1/2))]. The literature reported Soave-Redlich-Kwong equation of state (SRK EOS) parameters of pure polymer are employed. The PSRK model with the modified mixing rule is used to predict the vapor-liquid equilibrium (VLE) of 37 solvent-polymer systems over a large range of temperature and pressure with satisfactory results.