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The effect of temperature on the polymerization of propene with dimethylsilylbis(1‐indenyl)zirconium dichloride/methylaluminoxane and dimethylsilylbis(2‐methyl‐1‐indenyl)zirconium dichloride/methylaluminoxane. Modeling of kinetics
Author(s) -
Wester Thale Sofie,
Johnsen Heidi,
Kittilsen Pål,
Rytter Erling
Publication year - 1998
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(19980901)199:9<1989::aid-macp1989>3.0.co;2-5
Subject(s) - methylaluminoxane , propene , polymerization , monomer , zirconium , polymer chemistry , metallocene , chemistry , catalysis , activation energy , kinetics , inorganic chemistry , organic chemistry , polymer , physics , quantum mechanics
Propene polymerizations were performed using the two ansa ‐zirconocene catalyst systems dimethylsilylbis(1‐indenyl)zirconium dichloride/methylaluminoxane and dimethylsilylbis(2‐methyl‐1‐indenyl)zirconium dichloride/methylaluminoxane. The polymerization rate was observed by continuously monitoring the monomer consumption. Reaction rate profiles were obtained in the temperature range from 40°C to 130°C at pressures between 1 and 2.5 bar and catalyst concentrations from 4.6 · 10 −6 M to 4.2 · 10 −5 M. Isotacticity, as measured by NMR, melting point and molecular weight decreases markedly at higher temperatures. Small amounts of 1,3‐inserted monomer (<1 mol‐%) was observed at polymerization temperatures above 80°C. No 2,1‐inserted monomer was detected. A kinetic model was developed that describes the polymerization rate for Me 2 Si(Ind) 2 ZrCl 2 as the catalyst over the entire observed temperature range, and the polymerization rate for Me 2 Si(2‐Me‐Ind) 2 ZrCl 2 in a limited temperature range. The model includes an activation reaction, latent sites that may revert to active sites and a permanent deactivation that is second order with respect to the active sites. The activation energy for the propagation reaction was found to be 37 kJ/mol for Me 2 Si(Ind) 2 ZrCl 2 and 32 kJ/mol for Me 2 Si(2‐Me‐Ind) 2 ZrCl 2 /MAO. Several kinetic models are compared and discussed.