Abstract: A series of α-methylstyrene-styrene-acrylonitrile copolymers(α-MSAN)was synthesized via emulsion polymerization, which was employed to modify heat resistance and mechanical properties of ABS resin. DSC showed that at constant content of AN，the Tg of the α-MSAN copolymers increased linearly with increasing proportion of α-MSt. DMA indicated that the Tg of ABS resin containing α-MSAN shifted to higher temperature, while mechanical properties decreased slightly. When the ratio of α-MSt/St was 50/50 and the content of AN was 25%，the optimal comprehensive mechanical property of ABS resin was observed.

Key words: emulsion polymerization, α-methylstyrene, acrylonitrile-butadiene-styrene copolymer, heatresistance, glass transition temperature