ISSN:
0887-624X
Keywords:
long-chain branching
;
polymerization
;
catalysts
;
polyethylene
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Polyethylene produced by a vanadium-based polymerization catalyst contains long-chain branching as determined by NMR and rheology, even though the polymer has very low levels of vinyl unsaturation. A new mechanism is proposed for the formation of the long-chain branching, which involves C—H bond activation of the polyethylene backbone through a σ-bond metathesis reaction, followed by ethylene insertion at the new V—C bond. Consistent with the proposed C—H bond activation mechanism, the polymerization catalyst was also found to insert ethylene into the C—H bonds of alkanes such as heptane. A bridged metallocene catalyst was also found to activate C—H bonds of alkanes suggesting this new mechanism may explain the formation of long-chain branching in some metallocene-produced polyethylene. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2889-2898, 1998
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
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