Heterogeneity of active sites of Ziegler‐Natta catalysts: The effect of catalyst composition on the MWD of polyethylene | Zendy

Nikolaeva Marina I. | Zendy; Mikenas Tatiana B. | Zendy; Matsko Mikhail A. | Zendy; Echevskaya Ludmila G. | Zendy; Zakharov Vladimir A. | Zendy

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Heterogeneity of active sites of Ziegler‐Natta catalysts: The effect of catalyst composition on the MWD of polyethylene

Author(s) -

Nikolaeva Marina I.,

Mikenas Tatiana B.,

Matsko Mikhail A.,

Echevskaya Ludmila G.,

Zakharov Vladimir A.

Publication year - 2009

Publication title -

journal of applied polymer science

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 0.575

H-Index - 166

eISSN - 1097-4628

pISSN - 0021-8995

DOI - 10.1002/app.31359

Subject(s) - catalysis , polyethylene , ziegler–natta catalyst , natta , dispersity , molar mass distribution , titanium , polymerization , materials science , polymer chemistry , composition (language) , chemistry , chemical engineering , polymer , organic chemistry , linguistics , philosophy , ethylene , engineering

Experimental data on the molecular weight distribution (MWD) of polyethylene (PE) produced over a broad number of Ziegler‐Natta catalysts differing in composition and preparation procedure are presented. These catalysts include nonsupported TiCl 3 catalyst, four types of supported titanium‐magnesium catalysts (TMC) differing in the content of titanium and the presence of various modifiers in the composition of the support, and a supported catalyst containing VCl 4 as an active component instead of TiCl 4 . The studied catalysts produce PE with different molecular weights within a broad range of polydispersity ( M w / M n = 2.8–16) under the same polymerization conditions. The heterogeneity of active sites of these catalysts was studied by deconvolution of experimental MWD curves into Flory components assuming a correlation between the number of Flory components and the number of active site types. Five Flory components were found for PE produced over nonsupported TiCl 3 catalysts ( M w / M n = 6.8), and three–four Flory components were found for PE produced over TMC of different composition. A minimal number of Flory components (three) was found for PE samples ( M w / M n values from 2.8 to 3.3) produced over TMC with a very low titanium content (0.07 wt %) and TMC modified with dibutylphtalate. It was shown that five Flory components are sufficient to fit the experimental MWD curve for bimodal PE ( M w / M n = 16) produced over VMC. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

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