  Phase separation in mixtures of polymers and alkanes is investigated with the
aid of a recently developed lattice model, based on the Born-Green-Yvon (BGY)
integral equation approach to fluids. The system-dependent parameters of the
BGY lattice model for binary mixtures are deduced from those of its pure
components, which in turn are determined from a comparison with experimental
data. The lower critical solution temperatures (LCST's) for polyethylene in
various n-alkanes were predicted from the BGY lattice model and compared with
experimental data. While the model underestimates the LCST's for the smaller
alkanes it reproduces the experimental values very well for the higher alkanes
(decane through tridecane). The effect of the chain length of the polymer on
the solubility is investigated for the case of decane as a solvent.
