  A perturbation theory modification of the Flory-Huggins polymer solution
theory is presented. The proposed perturbation equation utilizes the results by
Tukur et al [J. Chem. Phys. 110 (7), 3463, 1999] for hard-sphere binary mixture
at infinite size ratio. The resulting perturbation theory equations are used to
predict properties of three different polymers with different molecular weights
in different solvents. Comparison of the proposed perturbation calculations
with those of the Flory-Huggins theory and the experimental data indicate that
the proposed perturbation method appreciably improves prediction of polymer
solution properties especially at large polymer / solvent size ratios.
