中文摘要：

研究了氢气和硅烷类外给电子体对负载型Z-N催化剂催化丙烯聚合微观动力学的影响.通过噻吩酰氯淬灭法测定了聚合体系的活性中心浓度和链增长速率常数（k p）.通过聚合物的萃取分级,得到了生成无规聚丙烯、中等规度聚丙烯和等规聚丙烯的三类活性中心的数量及其k p值.结果表明,氢气提高聚合活性的效应源于活性中心浓度和k p值的同时增大.三类活性中心的氢气响应特性显著不同.生成无规聚丙烯的活性中心的数量在加入氢气后变化幅度最小,而生成中等规度聚丙烯的活性中心的k p值在加入氢气后增加幅度最大.改变外给电子体也显著影响三类活性中心的氢气响应特性.增加外给电子体的烷基取代基空间位阻一方面降低了发生区域选择性和立体选择性插入错误的几率,同时也降低了氢气影响k p值的程度,说明氢气活化效应与活性中心的区域选择性和立体选择性密切相关.根据实验结果提出了氢气活化效应的微观机理模型.

英文摘要：

The kinetics of propylene polymerization with a TiCl4/ Di / MgCl2（ Di = internal donor） supported Ziegler-Natta catalyst was studied by measuring the number of active centers using 2-thiophenecarbonyl chloride as quenching agent. Influences of hydrogen and alkoxysilane type external donors on the number of active centers and chain propagation rate constant（ k p） were investigated. The number and k p value of three groups of active centers that produce atactic,medium-isotactic and isotactic polypropylene（ PP） fractions were determined. The catalyst activity was found to significantly increase with the addition of hydrogen,which was a result of simultaneous increases in the number of active centers and k p value. The three groups of active centers response to hydrogen differently. Hydrogen caused lower degree of increase in the number of active centers that produce atactic PP than the other two groups of active centers,and caused the highest degree of increase in the k p value of active centers that produce medium-isotactic PP. The hydrogen response of the active centers was also influenced by external donor. Increasing the bulkiness of alkyl groups in alkoxysilane donors leads to decreased hydrogen sensitivity,meanwhile the stereo- and regio-selectivities were evidently improved,implying that there are close relations between the hydrogen effect and the stereo-and regio-selectivities of the catalyst.A mechanistic model was proposed to explain the hydrogen effect.