Although the aforementioned styrene/conjugated diene block copolymers of A-B-A or A-B type wherein A is polystyrene and B is a polymer of a conjugated diene, and hydrogenated derivetives thereof, and styrene grafted polymers such as high impmact polystyrene, styrene grafted EPDM, styrene grafted EPR, styrene grafted EBR, and styrene/unsaturated functional monomer co-grafted EPDM have good compatib