DISTRIBUTION OF ACTIVE-CENTERS ON TICL4 MGCL2 CATALYST FOR OLEFIN POLYMERIZATION/

1-Octene was polymerized with TiCl4/MgCl2-AlEt3 and the polymerization was quenched with CH3COCl to introduce a CH3CO - group onto each prop agation chain. The polymer was fractionated by fractional precipitatio n, and the number of active centers in each fraction was determined by measuring the CH3CO - content of the fraction. Distributions of the n umber and reactivity of active centers among the fractions were determ ined and discussed based on these experiments. The active center distr ibutions were also studied by fitting the molecular-weight distributio n (MWD) curve from GPC with multiple Schulz-Flory most-probable distri butions. The uncontinuous reactivity distribution of active centers re veals that there exist limited types of active centers on the catalyst . Five types of active center were distinguished by the MWD fitting tr eatment. The correlations between the active center distributions and catalyst structures are discussed. (C) 1996 John Wiley & Sons, Inc.