Ti-Mg聚乙烯催化剂的制备及其分形形态的研究

应用分形理论研究了Ｔｉ－ Ｍｇ 负载型聚乙烯催化剂的形态。采用改进的盒子维法对扫描电镜照片进行分析计算，得到了催化剂及其聚合物的表面分维值。探讨了催化剂制备反应时间、反应温度及搅拌速率对催化剂表面形态的影响，以及催化剂分维值对聚合活性及其聚合产品形态的影响。结果表明，随着反应时间的延长和反应温度及搅拌速率的提高，催化剂表面的粗糙无规则度随之增加，聚合活性有所提高。而过低或过高的催化剂初始分维值对聚合物的形态都将产生不利的影响，因此在工业应用中催化剂分维值应选取一最佳范围。

Preparation and Fractal Morphology of Ti-Mg Polyethylene Catalyst

Ti-Mg supported polyethylene catalyst was studied with fractal dimension method.The support was formed in the process of preparing the catalyst.At the same time,activated Ti was supported.The catalyst surface morphology is influenced by reaction time,reaction temperature,stirring speed,etc.The fractal dimensions of these catalyst surfaces were calculated on the basis of SEM images.Furthermore,the influence of the fractal dimension on catalytic activity and the morphology of its polymerization product particles were discussed systematically. Prolonged reaction time and increased reaction temperature or stirring speed will roughen the catalyst surface and increase the fractal dimension value and initial polymerization activity.Notably,its influence on the polymer product morphology is much complex.Thus an optimum value of the catalyst fractal dimension should be adapted in industrial application.