环氧化三元乙丙橡胶增韧聚对苯二甲酸丁二酯的脆韧转变

环氧化的三元乙丙橡胶(eEPDM)与聚对苯二甲酸丁二酯(PBT)共混可以使PBT共混体的缺口冲击强度获得很大的提高.当eEPDM橡胶浓度为24wt%时,PBTeEPDM共混体的缺口冲击强度是纯PBT的12倍.随着eEPDM含量的增加,在室温下PBTeEPDM共混体出现了明显的脆韧转变,其脆韧转变的临界粒子间距为0.49μm.橡胶的加入及含量的增加使PBT体系的脆韧转变温度(TBD)向低温移动,且PBTuEPDM与PBTeEPDM共混体脆韧转变温度的差随橡胶含量的增加而逐渐增大.扫描电镜照片表明,在橡胶组成相同的情况下,PBT基体中分散的eEPDM粒子明显小于未环氧化的EPDM粒子.且eEPDM橡胶的粒子间距(ID)也明显地低于uEPDM橡胶粒子的ID,这导致PBTeEPDM共混体系在室温下出现脆韧转变.

BRITTLE-DUCTILE TRANSITION OF POLY(BUTYLENE TEREPHTHALATE) TOUGHENED WITH EPOXIDIZED EPDM RUBBER

Epoxidized ethylene propylene diene (eEPDM) was prepared in the lab.Then it was used to toughen poly(butylene terephthalate) (PBT) by melt 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 (unepoxidized EPDM) blends,the impact strength remained briefly unchanged with increasing the rubber content.It was obtained that the critical interparticle distance (ID_c) of the PBT/eEPDM systems is 0.49 μm.Moreover,the addition of EPDM led to the decreasing of the brittle-ductile transition temperature (T_(BD)) 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.