New insights into the impact toughness of ASA (acrylonitrile-styrene-acrylate) with controllable core–shell structure synthesized by three-stage seeded emulsion polymerization

Acrylonitrile-styrene-acrylate (ASA) with controllable core–shell structure was prepared through three-stage seeded emulsion polymerization. A series of characterizations had been performed to study the effect of different core–shell ratios on the properties of ASA. The most interesting was that the impact strength of ASA exhibited a “wave” variation instead of a linear variation with the increasing loading content of poly(butyl acrylate) (PBA) core. Moreover, the threshold of impact strength appeared at 49.725 wt% PBA content, nearly 33 kJ/m2. To explain this unusual variation, an impact schematic was proposed.