Thermodynamic interactions in polybutadiene blends

This paper describes a study of thermodynamic interactions in binary blends of statistical copolymers of 1,4-and 1,2-polybutadiene using differential scanning calorimetric measurements. The Flory-Huggins interaction parameter (chi) obtained for blends with component compositions ranging from 88 to 90% 1,2-polybutadiene were found to be inconsistent with the simple random copolymer theory. The reduced interaction parameter, chi/Delta y(2), was found to be a strong function of the average composition of the blend, in close analogy to an earlier study on ethylene-butene-1 copolymers prepared by saturation of 1,4-polybutadiene-1,2-polybutadiene copolymers. However, values for chi/Delta y(2) for the polybutadiene blends were considerably smaller than those present in the ethylene-butene-1 copolymers over comparable ranges of copolymer composition. The PVT properties of the polybutadiene copolymers, on the other hand, suggest a much larger interaction as well as adherence to the random copolymer theory.