Microscopic Equations-of-State for Hydrocarbon Fluids: Effect of Attractions and Comparison with Polyethylene Experiments

Microscopic equations-of-state are developed for n-alkanes and polyethylene based on the polymer reference interaction site model (PRISM) integral equation theory and a generalized Flory approach. The molecules are modeled as a series of overlapping spheres (methylene groups ) with constant bond length and bond angles; internal rotations are accounted for by the rotational isomeric state approximation. The interaction between sites on different molecules is taken to be of the Lennard-Jones form. the thermodynamic properties of the fluid are obtained via standard perturbation.