Epoxidized ethylene propylene diene (eEPDM) was prepared in the lab．Then it was used to toughen poly (butylene terephthalate) (PBT) by meh blending．For the blend with 24 wt％ eEPDM content

the impact strength is 12 times of that of pure PBT．Moreover

the brittle．ductile transition could be found by increasing eEPDM content at room temperature However

for PBT/uEPDM (unepoxldized EPDM) blends

the impact strength remained briefly unchanged with increasing the rubber content．It was obtained that the critical interparticle distance (IDe) of the PBT/eEPDM systems is 0.49μm Moreover

the addition of EPDM led to the decreasing of the brittle-ductile transition temperature (TBD) of PBT/EPDM blends．The difference between the brittle-ductile transition temperatures of PBT/uEPDM and PBT/eEPDM blends increased considerably with increasing EPDM content．SEM photographs showed that dispersed eEPDM particle size was obviously smaller than that of uEPDM particle in PBT matrices．Moreover

the interparticle distance(ID) of the PBT

eEPDM blends was smaller than that of the PBT/uEPDM blends

which led to the occurrence of brittle-ductile transition of PBT/eEPDM blends at room temperature．