Blends of Polystyrene-(Styrene Butadiene) rubber copolymers were prepared in a twin screw extruder and then injected. The samples were characterized by various techniques and their properties compared to those of a sample with 0% rubber content. The results show that the morphology of the segregated phases in the blends as well as the chemical architecture of the rubber phase have a definite influence on the mechanical and rheological properties of these materials.