乙丙共物聚的结晶速率与序列结构

本文用(体)热膨胀计法研究了共聚物组成、催化体系对乙丙共聚物结晶速率的影响。结果表明,同一催化体系乙丙共聚物的最大结晶速率(1/t_((1/2)(max)))随共聚物中乙烯含量的增加而增大。不同催化体系对二元乙丙共聚物的1/t_((1/2)(max))次序为:VOCl_3~->V_(5-9~-)>V_((aca?)3~-)。加入活化剂ETCA的各催化体系的二元乙丙共聚物的1/t_((1/2)(max))为VOCl_3~-ETCA>V_(5-9~-)ETCA>V_((ocac)~-)ETCA。结合结晶度、T_g、以及不同序列分布共聚物组成的测定,可推测VOCl_3~-体系乙丙共聚物具有较长的聚乙烯序列结构,V_(5-9~-)体系次之,V_((acac)_3~-)体系的乙丙共聚物分子链有更多的无规结构。

CRYSTALLIZATION RATE AND SEQUENCE STRUCTURE OF ETHYLENE-PROPYLENE COPOLYMERS

The effects of the catalyst system and composition of ethylene-propylene copolymers onthe crystallization rates of the copolymer have been studied by dilatometry. It is shownthat for the same catalyst system, the maximum crystallisation rate 1/t_1)_2 (max) of thecopolymer increased with the increase of the ethylene content in it.The maximum crystal-lization rates of ethylene-propylene copolymers obtained with various catalyst systemswere found in the following order:(VOCl_3-)> (V_(5-0))>(V(acac)_3-)The order of 1/t_1/2 (max) for the catalyst system with addition of an active agentETCA was:(VOCl_3 -ETCA) > (V_(5-9)-ETCA)> (V(acac)_3 -ETCA)The results of the crystallinity and glass transition temperature of the coplymers, aswell as the composition of copolymers of differnt sequence suggested that the ethylene-propylene copolymer obtained with VOCl_3-had longer PE species and those obtained withV_(5-9)- had shorter PE species. More irregular structure was formed when the copolymer isobtained with V (acac)_3 -catalyst system.