Abstract
A novel toughening modifier, styrene–isoprene–butadiene rubber (SIBR), was used to improve the impact resistance and toughness of acrylonitrile–butadiene–styrene (ABS) resin via bulk polymerization. For comparison, two kinds of ABS samples were prepared: ABS‐1 was toughened by a conventional modifier (a low‐cis polybutadiene rubber/styrene–butadiene block copolymer), and ABS‐2 was toughened by SIBR. The mechanical properties, microstructures of the as‐prepared materials, and fracture surface morphology of the specimens after impact were studied by instrumented notched Izod impact tests and tensile tests, transmission electron microscopy, and scanning electron microscopy, respectively. The mechanical test results show that ABS‐2 had a much higher impact strength and elongation at break than ABS‐1. The microscopic results suggested that fracture resistance of ABS‐1 only depended on voids, shear yielding, and few crazing, which resulted in less ductile fracture behavior. Compared with ABS‐1, ABS toughened by linear random SIBR (ABS‐2) displayed the synergistic toughening effect of crazing and shear yielding, which could absorb and dissipate massive energy, and presented high ductile fracture behavior. These results were also confirmed by instrumented impact tests. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011