Morphology and crack resistance behavior of binary block copolymer blends

Fracture behavior of binary blends comprising of styrene–butadiene block copolymers having star and triblock architectures was studied via instrumented Charpy impact test. The toughness of the ductile blends was characterized by dynamic crack resistance curves (R-curves). tudy represents a systematic investigation of crack resistance behavior of nanometer structured binary block copolymer blends and the development of a new material with a combination of high toughness and transparency, usually not observed in incompatible polymer blends. While the lamellar star block copolymer shows an elastic behavior (small-scale yielding and unstable crack growth), adding of 20 wt% of the triblock copolymer leads to a stable crack growth and at 60 wt% of the triblock copolymer the strong increase of toughness values indicate a tough/high-impact transition, demonstrating the existence of novel toughening concepts for polymers based on nanometer structured materials.