Toughness of ABS/PBT blends: The relationship between composition, morphology, and fracture behavior

A series of acrylonitrile–butadiene–styrene (ABS) copolymer/poly(butylene terephthalate) (PBT)/acrylonitrile‐styrene‐glycidyl methacrylate (ASG) blends with various compositions were prepared and characterized in this study. When the fraction of ABS exceeds a critical value there is a rapid increase in notched impact strength of ABS/PBT blends no matter whether the compatibilizer ASG is present. By combining morphology observation and notched impact results, we found that the ductile‐brittle transition of the blends is closely related to the morphology inversion. The notched impact strength jumps from 15.9 to 33.4 kJ/m2 when phase inversion of ABS occurs at its fraction of 58 wt %. Accordingly, a possible toughening mechanism involved in the blends is proposed on the basis of a careful analysis of fracture energy, crack propagation behavior and fracture surface morphology. It is believed that the continuous ABS phase plays the critical role in toughening ABS/PBT blends.