A Facile Toughening Strategy for Styrene–Acrylonitrile Copolymer Through Dynamic Vulcanization of Acrylonitrile‐Butadiene Rubber

ABSTRACT The rising demand for polymers in engineering fields requires additional techniques to improve the toughness of inherently brittle plastics. Here, a strategy is proposed to toughen the brittle styrene–acrylonitrile copolymer (SAN) through dynamic vulcanization. Acrylonitrile‐butadiene rubber (NBR) is introduced as a toughening agent, while dicumyl peroxide (DCP) is used as a curing agent to initiate dynamic vulcanization. The resulting SAN/NBR TPVs exhibit a co‐continuous structure, different from the traditional “sea‐island” structure of classical TPVs. The continuous NBR network functions as a pathway for stress transfer, playing a key role in toughening SAN. Significant plastic deformation and stretched microfibrils with high orientation form along the impact direction, absorbing energy and enhancing toughness. With 40 phr NBR, the SAN/NBR TPVs achieve an impact strength of 53.5 kJ/m 2 and a tensile toughness of 18.4 MJ/m 3 , which are 29.7 and 12.2 times higher than those of the neat SAN, respectively. Meanwhile, the tensile strength of the TPVs remains nearly the same as that of the simple blend.