ESTIMATION OF EOS INTERACTION PARAMETERS FROM SCATTERING AND PREDICTIONS OF PHASE-DIAGRAM FROM THEM

The interaction energy parameter (X(12)), and the interaction entropy parameter (Q(12)) of the Flory's equation-of-state theory were determi ned from the Flory-Huggins interaction parameter, chi, which was measu red from scattering data for the miscible blend systems, polystyrene ( PS)/poly(vinyl methyl ether) (PVME) and deuterated polystyrene (dPS)/P VME blends. The phase diagram of the polymer mixture was predicted fro m the values of X(12) and Q(12). The spinodal curve predicted from the ory showed a similar shape to the experimental one although the lower critical solution temperature from theory is ca. 10-70 degrees C highe r than the experimental values. It was found that a small difference i n the chi values leads to a large shift of spinodal curve. On the othe r hand, the parameters X(12) and Q(12) were determined by fitting the EOS theory to experimental data, and then the parameter chi was calcul ated from the best-fit values of X(12) and Q(12). The parameter chi ca lculated from theory showed a composition dependency which was in good agreement with those obtained from the neutron scattering measurement s. Copyright (C) 1996 Elsevier Science Ltd.