复合载体法制备聚丙烯-蒙脱土复合材料

将传统Z-N催化剂TiCl4负载于蒙脱土．乙醇镁复合载体上，进行丙烯常压原位聚合，制备聚丙烯-蒙脱土纳米复合材料，克服了单-蒙脱土作载体时聚合活性低、产物分子量小的缺点。对比不同制备过程的催化剂，发现TiCl4的后处理可以大幅提高催化活性。引入苯乙烯可有效降低Mg—MMT／Mg(OEt)2/TiCl4/EB体系制备的Cat5催化聚合时所需的Al／Cat比。由Mg—MMT／Mg(OEt)2/Ti(OBu)4/TiCl4/EB体系制备的Cat6具有活性高，所需Al／Cat低的优点，为合适的制备聚丙烯-蒙脱土纳米复合材料的催化剂。WAXS和TEM表明复合材料中蒙脱土主要呈剥离杰分散干聚丙烯基体中。产物的熔点和商用聚丙烯的熔点接近。

Preparation of Polypropylene/MMT Nanocomposites Using Complex Supported Catalysts

A new type of heterogeneous Z-N catalyst was prepared by using mixture of Mg-Montmorillonite (MMT) and Mg(OEt)2 as complex support. Using the complex supported catalysts the polypropylene(PP)/MMT nanocomposites were produced via in-situ polymerization. The complex supported catalysts have much higher catalytic activity and give higher PP molecular weight than catalysts using MMT as support alone. The catalytic activity was increased and the Al/Cat ratio needed for polymerizing could be reduced when retreatment of TiCl4 was applied during the support procedure. It is found that under lower Al/Cat ratio, the activity of the complex supported catalyst Cat 5 prepared from Mg-MMT/Mg(OEt)2/TiCl4/ EB can be improved by adding a few amount of styrene during polymerization. Among all the complex supported catalysts studied, the Cat 6 prepared from Mg-MMT/Mg(OEt)2/ Ti(OBa)4/ TiCl4/ EB has the best performance of high activity and low Al/Cat needed, and it is believed to be the suitable catalyst for the preparation of PP/MMT nanocomposites. Results from WAXS analysis and TEM observation of the composites indicate that MMT layers have exfoliated and dispersed in PP matrix during polymerization. The melt temperature (Tm) of the products is similar to commodity PP.