Preparation and application in toughening SAN resin of BA/St-co-AN core-shell structured copolymer

n-butyl acrylate/styrene-co-acrylonitrile structured core/shell copolymer (AAS) was prepared by seeded emulsion polymerization. Gravimetric analysis was used to measure the conversion of monomer to polymer throughout the reactions and revealed that the polymerizations had proceeded under monomer-starved conditions (the instantaneous conversion>93%). The good agreement shown between experimental and theoretical particle diameters throughout the polymerization for all latexes provides strong evidence that the particles are grown without significant secondary nucleation and all the polymer particles formed are spherical. The molecular movements of AAS/ acrylonitrile-co-styrene blends with different PBA contents were characterized by dynamic mechanical analysis (DMA). The low T_g1s, corresponding to that of poly(n-butyl acrylate) (PBA) are changed slightly, while the high T_g2s, corresponding to that styrene-co-acrylonitrile copolymer, are changed greatly. This shows the significant gradient layer is formed at the surface of core and shell layers. The AAS/SAN blend occurrs from the brittle fracture to ductile one when the PBA content accounts for about 15%, and the tensile strength keeps relative high values. The SEM observation proves results of mechanical properties.