A study of the miscibility of blends of polybutadiene and styrene‐butadiene copolymers

Abstract We investigated the miscibility of polybutadienes with butadiene‐styrene copolymers of varying styrene content. The methods of optical microscopy, differential scanning calorimetry, and small angle light scattering (SALS) were used. All polymers/copolymers used in this study have equivalent butadiene microstructures. Copolymers with high styrene levels are immiscible with polybutadiene. The tendency to miscibility increases with decreasing styrene content. An upper critical solution temperature is observed with the 23 percent styrene copolymer.