Vapor-liquid equilibria of polymer solutions determined by molecular mechanics

A method of calculating interaction parameters used in phaseequilibrium calculations has been extended for predicting solventactivities of polymer solutions. A pair of interaction parameters aredetermined by calculating interaction energies between all pairs ofmolecules in the solution of interest with a molecular mechanicsmethod called the Consistent Force Field (CFF). The conformationalspace of a pair of molecules is sampled with a Monte Carlo algorithmfollowed by energy minimizations. The method is used to calculatesolvent activities for the diethylketone/polypropylene system, givingresults in good agreement with experimental values. Furthermore,solvent activities are predicted for the diethylketone/polyethylenesystem for which no experimental data are available. The method isfully predictive, as no fitting to experimental phase-equilibrium datais carried out.