title: Study on the distribution of active centers in novel low Ti-loading MgCl2-supported Ziegler-Natta catalyst.
abstract: Novel MgCl2-supported Ziegler-Natta (Z-N) catalysts prepared using a new one-pot ball milling method can effectively control the amounts of Ti-loading in the catalysts. Complex GPC data on polypropylene synthesized by these novel catalysts were analyzed using the method of fitting the molecular weight distribution (MWD) curves with a multiple Flory-Schulz function. It was found that multiple active centers exist in these novel catalysts. Detailed study of the effects of the Ti-loadings in the catalysts on the distribution of the active centers showed that the Ti-loadings in the novel MgCl2-supported Z-N catalysts might affect the proportion of each type of active centers; and might be the main factor responsible for the effect of the Ti-loadings on the microstructure, the molecular weight and molecular weight distribution width of the resultant polymer, the catalytic activity and polymerization kinetics.
authors.affiliation: State Key Lab of Polymer Reaction Engineering, College of Materials Science and Chemical Engineering, Zhejiang University, Hangzhou 310027, China.
authors.forename: Jian-Feng
authors.initials: JF
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Zhen-Rong
authors.initials: ZR
authors.lastname: Zhao
authors.forename: Wen-Qing
authors.initials: WQ
authors.lastname: Wang
authors.forename: Tao
authors.initials: T
authors.lastname: Chen
mesh_terms: D002384:Catalysis; D015636:Magnesium Chloride / Q000737:chemistry; D008970:Molecular Weight; D011126:Polypropylenes / Q000138:chemical synthesis*; D014025:Titanium / Q000737:chemistry
chemical_list: D011126:Polypropylenes; D015636:Magnesium Chloride; D014025:Titanium