MODIFIED INTERPENETRATION FUNCTION ACCOUNTING FOR THE EXCLUDED-VOLUME EFFECTS IN TERNARY POLYMER SYSTEMS

The excluded-volume effect in polymer-mixed-solvent systems has been investigated in the light of the two-parameter theory. These multicomponent polymer systems exhibit some specific features quite different from polymer-single-solvent systems, involving ternary interactions and the synergic action of the mixed solvents at a given composition on polymer dimensions. Both effects are taken into account in order to derive a new expression for the interpenetration ternary function, Psi(T), and the expansion factor, alpha(s), both being quantitatively evaluated for ternary systems based on polystyrene and poly(methyl methacrylate). In addition, a complementary treatment of the excluded-volume effects, proposed by Wolf, based on the evaluation of the intra- and inter-molecular interactions has been carried out.