Three types of novel impact modifiers were prepared by melt blending maleic anhyaride—grafted ethylene-octene copelymer(POE-g-MAH)with polypmpylene(PP)through a twin screw extruder．The effect of different impact modifier and its content on mechanical properties

dispersion morphology and melting and crystallization behavior of the blends was investigated．The mechanical property testing indicates that POE—g—MAH and PP have significantly synergistic toughening effect on PBT．The impact modifier(POEg2)with POE—g-MAH／PP ratio of 70／30 has the best toughening effect．When POEg2 content is up to 15％

the notched impact strength(Ig)increases from 7．5 kJ／m2 for pure PBT to 51．2 kJ／m2

which is approximately equal to that for the blend toughened by 15％ pure POE-g-MAH

and the loss of tensile strength(σb)of the blend is the least．The impact modifier particles dispersed in matrix have a soft shell—rigid core morphology evidenced by using AFM and SEM．DSC results reveal that the soft shell in shell-core structurat particles becomes incomplete

when the PP content in the impact modifier is high(50％)．It may which result in a decline in interaction between the blend components

and consequently

Is and σb of the blend both begin to decrease obviously．