Plurality of Active Centers on Heterogeneous Ziegler-Natta Catalysts(Ⅰ)--Studies on the Molecular-Weight Distribution of Polymer Synthesized by Titanium Catalysts

Abstract

Abstract: The molecular-weight distribution (MWD) graphs of polyoctene-1 synthesized by TiCl₃or TiCl₄/MgCl₂with A1(C₂H₅)₃, A1G-C₄H₉)₃or A1(C₂H₅)₂Cl were accurately fitted with 3-5 Schulz-Flory "the most probable" distributions of different position and area, and the position and area of the theoretical distributions change regularly with the catalyst and polymerization conditions, showing that each of the "the most probable" peaks corresponds to a certain kind of active center, and the broad MWD (M_w/q_n=3-12) of the studied polymer is the results of 3-5 kinds of active centers. The plurality of active centers was also evidenced by measuring thenumber of active centers in the polymer fractions of different molecular-weight. The characteristics of different active centers as well as the polymerization mechanism are discussed based on the results of MWD fitting.

Key words: Ziegler-Natta catalyst, Active center, Plurality, Molecular-weight distribution

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Fan Zhi-qiang, Feng Lin-xian, Yang Shi-lin . Plurality of Active Centers on Heterogeneous Ziegler-Natta Catalysts(Ⅰ)--Studies on the Molecular-Weight Distribution of Polymer Synthesized by Titanium Catalysts[J]. Chem. J. Chinese Universities, 1991, 12(12): 1681.

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Plurality of Active Centers on Heterogeneous Ziegler-Natta Catalysts(Ⅰ)--Studies on the Molecular-Weight Distribution of Polymer Synthesized by Titanium Catalysts

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