利用^1H—NMR研究HDPE／PET／EVA共混体系的酯交换反应

STUDY ON TRANSESTERIFICATION OF HDPE/PET/EVA BLENDS BY 1H-NMR

本文在选用EVA作为HDPE/PET共混体系增容剂的基础上 ,通过双螺杆反应挤出熔融加工过程 ,促使EVA侧基上的酯基官能团与PET组分主链上的酯基在适当催化剂———有机金属化合物存在的条件下发生酯交换反应 .1H NMR结果表明 ,酯交换反应的产生在共混体系界面原位形成接枝或交联的PET EVA共聚物 ,且主要是以生成接枝共聚物的反应为主 .

HDPE and PET are known to be imcompatible polymers.To improve the properties of HDPE/PET blends,ethylene vinyl acetate copolymer(EVA) was used as a compatibilizer in this system.Owing to chemical structure similarities,EVA displays some miscibility with HDPE.On the other hand,ester groups of EVA can react with the polyester macromolecules and form PET\|EVA copolymers as compatibilizers in situ during reactive processing through twin screw extruder by transesterification reactions in the presence of catalyst\|organometallic compound.The results of \{\}\+1H\|NMR show that grafted or co\|crosslinked copolymers PET\|EVA was generated at the interface of blends by transesterification during processing operation with organometallic compound,which enhanced the compatibilization of HDPE/PET blends.Transesterification reaction between PET and EVA led to a grafted copolymer mainly.