Control of Particle Size and Gel Content During Semicontinuous Emulsion Polymerization of Butyl Acrylate and Its Toughening Effect in <scp>SAN</scp> Resins

ABSTRACT Styrene–acrylonitrile copolymer (SAN) is widely used in various industries due to its excellent transparency, rigidity, and chemical resistance, but its brittle properties limit its utilization and development in niche areas. To improve the brittle properties of SAN resins for more applications, different PBA latexes were synthesized in this study by semicontinuous emulsion polymerization, and two key factors affecting the toughening effect of the resins, particle size and gel content of the poly butyl acrylate (PBA) rubber particles, were effectively and easily controlled. It was found that the crosslinker content and monomer dropping time could control the gel content of PBA latex, while the particle size of the latex was affected by the emulsifier distribution ratio and monomer dropping time. In addition, acrylate styrene acrylonitrile (ASA) resins were constructed by blending PBA‐g‐SAN graft copolymers with SAN resins, and impact strength tests were conducted to demonstrate the toughening effect on SAN resins. The experimental results show that the gel content can be as low as 73.03%, the particle size varies from 200 nm to 530 nm, and the maximum impact strength of ASA resin reaches 6.17 kJ/m 2 .