On intermolecular interactions in solutions of polymer blends

Phase diagrams for solutions of blends of a series of homopolymers and random polymers were obtained and compared with the dependences of the second virial coefficient A(2) and intensity of excess light scattering R-90" on the ratio of the polymer concentrations in solution. The mutual solubility of polymers correlates with the values of R-90" and A(2): the larger the deviations of these parameters from the corresponding additive values, the lower the thermodynamic compatibility of the polymers. Introduction of a third polymer into a binary blend enhanced the interaction between unlike molecules, as manifested in a decrease in the deviation of A(2) and R-90" from their values predicted with the additivity rule, thus indicating an increased mutual solubility of polymers in the ternary system.