L. An and B. A. Wolf

"Application of the Sanchez-Lacombe lattice fluid theory to the system
PVME/PS and model calculations"

*J. Macromol. Sci., Pure and Appl. Chem.* **1997**, *A34*, 1629-1644.

**Abstract:** Cloud point curves reported in the literature for five representatives
of the system poly(vinyl methyl ether)/polystyrene were evaluated theoretically
by means of the Sanchez-Lacombe lattice fluid theory. The measured phase separation
behavior can be described within experimental error using only one adjustable
parameter (quantifying the interaction between the unlike mers). The Flory-Huggins
interaction parameters calculated from this theoretical description depend in
good approximation linearly on composition (volume fractions) and on the inverse
temperature. An evaluation of these data yields a maximum heat effect which
is almost one order of magnitude less (ca. -0.25 J/cm(3)) than obtained via
Hess's cycle (dissolution of the components and of the blend) from calorimetric
measurements. Model calculations on the basis of the present theory demonstrate
that the critical points shift to a different extent upon a certain relative
change in the molar mass of the blend components. The sensitivity of the calculated
phase diagrams against changes in the scaling parameter decreases in the following
order: interaction energies between unlike mers, differences in the scaling
temperatures, pressures and densities.

preprint number: 175