聚合温度对负载型Ziegler-Natta催化剂催化丁二烯-异戊二烯共聚合的影响

非均相TiCl₄/MgCl₂-AlR₃型Ziegler-Natta（非均相Z-N）催化剂是聚烯烃工业最重要的催化剂，经烷基铝活化的非均相Z-N催化剂具有复杂的活性中心结构，改变聚合温度、聚合时间、烷基铝种类及浓度等均会影响活性中心结构与催化性能.本文研究了不同聚合温度下TiCl₄/MgCl₂-AlEt₃（三乙基铝）催化丁二烯（Bd）和异戊二烯（Ip）的共聚合动力学，研究发现，随着聚合时间的延长，聚合活性先升高然后降低，在50℃聚合活性最高.采用核磁共振波谱（¹H NMR）、紫外荧光定硫仪和凝胶渗透色谱（GPC）研究了共聚物的微观结构、活性中心数和分子量及其分布，发现随着聚合时间的延长及聚合温度的升高，活性中心数、共聚物中反式-1，4-结构、分子量及分子量分布均发生不同规律的变化.本文研究结果可为进一步理解非均相Z-N催化剂在不同聚合温度下催化共轭二烯烃聚合的动力学及其关键影响因素提供参考.

Effect of the Polymerization Temperature on the Copolymerization of Butadiene and Isoprene Catalyzed by Supported Ziegler-Natta Catalyst

As the most important catalysts in polyolefin industry, heterogeneous TiCl₄/MgCl₂ Ziegler-Natta(Heterogeneous Z-N) catalysts activated by alkylaluminium show complex active center structures, which are sensitive to polymerization temperature, polymerization time, type and concentration of alkylaluminium. In this paper, the copolymerization kinetics of butadiene(Bd) and isoprene(Ip) catalyzed by TiCl₄/MgCl₂-AlEt₃(triethylaluminium) at different polymerization temperatures were studied. It was found that the activity of the copolymerization increased firstly and then decreased with the increase in the polymerization time, and the highest activity was observed at 50℃. The microstructure, the number of active centers, molecular weight and molecular weight distribution of the copolymers studied by proton nuclear magnetic resonance(¹H NMR), microcoulometric sulfur spectrometer and gel permeation chromatography(GPC) changed in different ways with the increase in polymerization temperature and polymerization time. The results of this study is helpful for further understanding the kinetics and its key influencing factors of conjugated diolefin polymerization catalyzed by heterogeneous Z-N catalysts under different polymerization temperatures.