不同乙烯含量丙烯无规共聚物结构表征

Structural characterization of polypropylene random copolymers with different ethylene contents

采用聚丙烯Ziegler-Natta催化剂及淤浆聚合法考察了乙烯-丙烯共聚行为,获得了不同乙烯含量丙烯无规共聚物,分别通过傅里叶红外光谱(FT-IR)、差示扫描量热(DSC)、凝胶渗透色谱(GPC)和13C NMR核磁谱进行了结构和性能表征。结果表明,随着原料中乙烯含量的增加,催化剂的共聚合活性增大,丙烯无规共聚物中乙烯含量增加,共聚物由以丙烯链段为主逐渐过渡到以乙烯链段为主;当反应原料中乙烯质量分数介于15%～30%时,共聚物的DSC测试结果达到较低值;共聚物的数均分子量和重均分子量均达到最低值,同时,共聚物中乙烯和丙烯在聚合物链段中的分布更均匀。

The structures and properties of polypropylene random copolymers with different ethylene contents, synthesized via slurry polymerization, were characterized with FT-IR, DSC, GPC, and 13C NMR. It was demonstrated that with the increase of ethylene content in the feed gas, the polymerization activity of catalyst as well as the ethylene content in the resulting random copolymer increased, and the copolymer also changed from mainly propylene segments to mainly ethylene segments. It was also shown that when the percentage of ethylene in the feed gas was 15%～30%, the DSC data of the copolymer reached relatively lower values, the corresponding relative molecular weight was at its minimum, and the distribution of ethylene and propylene segments in the copolymer became more uniform.