Influences of methylaluminoxane separated by porous inorganic materials on the isospecific polymerization of propylene

摘要

Inorganic siliceous porous materials such as Mn type zeolite, mesoporous silica MCM-41 and silica gel with different average pore diameters were applied to the adsorptive separation of methylaluminoxane (MAO) used as a cocatalyst in alpha-olefin polymerizations. The separated MAOs combined with rac-ethylene-(bisindenyl)zirconium dichloride (rac-Et(Ind)(2)ZrCl2) were introduced to propylene polymerization, and their influences on the polymerization activity and stereoregularity of the resulting polymers were investigated. The polymerization activity and isotactic mmmm pentad of the produced propylene were markedly dependent upon the pore size of the porous material used for adsorptive separation. From the results obtained from solvent extraction of the produced polymers, it was suggested that there are at least two kinds of active species with different stereospecificity :in the rac-Et(Ind)(2)ZrCl2/MAO catalyst system. References: 22