Abstract: Two special mastcrbatchcs were made by blending epoxy resin(EP>，polystyrene(PS>，and ethylene-propylene-dicnc monomer(EPDM)or acrylic acid grafted ethylene-propylene-dicnc monomer (EPDM-g-nn)， which were separately used in the PS/EPDM blends as a compatibilizcr.
While both compatiblizcrs improved the impact strength of PS/EPDM blends，the EPDM based one gave rise to an increase of 109%，compared with the plain blend. The EPDM based compatibilizcr made EPDMdispersed finer in PS matrix，resulting in more plastic deformation in the notch surface than EPDM-g-nn based one. When the curing agent content was 15%一20%，the best compatibilization was achieved，evidenced by the lowest toluene extraction mass.

Key words: polystyrene, cthylcn}propylcn}dicnc copolymer, blend, epoxy resin, compatibilization