Modeling polyethylene-solvent mixtures with the Sanchez–Lacombe equation

The Sanchez–Lacombe equation of state was used to model cloud-point isotherms of two systems of polyethylene in ethylene and in one system of polyethylene in n-hexane. The three polyethylene samples examined were very dissimilar in average molar mass and polydispersity. Alternative solvent parameter sets were considered. Polymer parameters were obtained by fitting pure polyethylene volumetric data using an additional volume shift coefficient. Excellent agreement with the experimental cloud-point data could be achieved for all three systems mentioned above. Henry’s constants for ethylene in polyethylene were also well matched by the same parameter sets.