SIMULATION OF THE SOLUBILITY OF ALKANES IN POLYETHYLENE

Novel methods for simulation of the chemical potential and for simulation of phase equilibria in systems of chain molecules have been developed. These methods are applied here to simulate Henry's constants and solubility for linear alkanes in polyethylene. The results of our simulations are in good agreement with experiment. At moderate pressures, the solubility of an alkane in polyethylene exhibits strong deviations from ideal behavior, thereby rendering Henry's law of little use; our solubility simulations, however, are able to reproduce the experimentally observed saturation of the polymer by the alkane. For low concentrations of the solute in the polymer, simulations reveal the presence of ''pockets'' in the polymer in which solubility occurs preferentially. At higher concentrations, the distribution of the solute in the polymer becomes relatively uniform.