Titanium, Zirconium Metallocene Samarium Metallocene Compound Catalytic Methyl Methacrylate And Ethylene Polymerization Studies

Metallocene catalysts have been established as excellent catalysts for the polymerization after the Ziegler-Natta catalyst. The produced polyolefins have narrow molecular weight distributions due to identical active sites of the catalyst.The narrow molecular weight distributions bring some problems to industrial processing. The research demonstrates that the dinuclear complexes, which has two different active sites, could be able to produce polymers with broader molecular weight distributions. The composed catalyst system may contains two different active sites, which may be similar to the dinuclear complexes. So we synthesize several metallocene catalysts and choose some of them to constitutes composed catalyst system,then examine their catalytic properties.Five composed catalyst systems were prepared. A. Cp2SmCl composed with Cp2TiCl2 B.Cp2SmCl composed with Cp2ZrCl2,C.(MeCp)2SmCl composed with Cp2TiCl2,D. (t-BuCp)2SmClcomposed with Cp2TiCl2 E. (t-BuCp)2SmCl composed with Cp2ZrCl2.Polymerization of MMA was catalyzed by A and B system .activated with Al G'-Bu) 3, produce polymer with high molecular weight, and relatively high conversion. We changed some polymerization conditions to focus the molecular weight and conversion, including the MMA/Cat molar ratio, the temperature, Al/Cat molar ratio and the polymerization time.The composed catalyst C, D and E have been used for the polymerization of ethylene activated by MAO. With the change of polymerization condition such as MAO/Cat molar ratio ,the concentration of catalyst, the polymerization time and temperature, some special behaviors were found.With the research on the five composed catalyst systems, we found several rules about them and made some conclusions...