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首页> 外文期刊>Journal of Applied Polymer Science >Comonomer Effects in Copolymerization of Ethylene and 1-Hexene with MgCl2-Supported Ziegler-Natta Catalysts: New Evidences from Active Center Concentration and Molecular Weight Distribution
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Comonomer Effects in Copolymerization of Ethylene and 1-Hexene with MgCl2-Supported Ziegler-Natta Catalysts: New Evidences from Active Center Concentration and Molecular Weight Distribution

机译：MgCl2-负载的Ziegler-Natta催化剂在乙烯和1-己烯共聚反应中的共聚单体效应：活性中心浓度和分子量分布的新证据

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摘要

In this article, comonomer effects in copolymerization of ethylene and 1-hexene with four MgCl2-supported Ziegler-Natta catalysts using either ethylene or 1-hexene as the main monomer were investigated. It was found that no matter which monomer was used as the main monomer, the polymerization activity was significantly enhanced by introducing small amount of comonomer. In copolymerization with ethylene as the main monomer, the strength of comonomer effects was much stronger in active centers producing low-molecular-weight polymer than those producing high-molecular-weight polymer. In copolymerization with 1-hexene as the main monomer, the number of active centers ([C*]/[Ti]) was determined, and the propagation rate constants (k(p)) were calculated. Deconvolution of the polymer molecular weight distribution into Flory components were made to study the active center distribution. Introduction of small amount of ethylene caused marked increase in the number of active centers and decrease in average chain propagation rate constant. Introducing internal electron donor in the catalyst enhanced not only the number of active centers but also the chain propagation rate constant. In copolymerization of 1-hexene with small amount of ethylene, the internal donor weakened the comonomer effects to some extent and changed the distribution of comonomer effects among different types of active centers. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41264.
机译：在本文中，研究了乙烯和1-己烯与四种以乙烯或1-己烯为主要单体的MgCl2负载的齐格勒-纳塔催化剂共聚的共聚单体效应。发现无论使用哪种单体作为主要单体，通过引入少量的共聚单体都可以显着提高聚合活性。在以乙烯为主要单体的共聚中，在生产低分子量聚合物的活性中心中，共聚单体作用的强度比生产高分子量聚合物的活性中心强得多。在以1-己烯为主要单体的共聚中，确定活性中心的数目（[C *] / [Ti]），并计算传播速率常数（k（p））。将聚合物分子量分布反卷积为Flory组分，以研究活性中心分布。引入少量乙烯会导致活性中心数量明显增加，平均链增长速率常数降低。在催化剂中引入内部电子给体不仅提高了活性中心的数量，而且提高了链增长速率常数。在1-己烯与少量乙烯的共聚中，内部给体在一定程度上减弱了共聚单体效应，并改变了不同类型活性中心之间共聚单体效应的分布。 （c）2014 Wiley Periodicals，Inc. J. Appl。 Polym。科学2015，132，41264。

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