The polyethylene obtained in the presence of the catalyst constituted by the meso isomer of the prototypical zirconocene complex (ethylene)bis(1-indenyl)zirconium dichloride activated by methylalumoxane is characterized by the presence of ethyl branches. The intensities of the 13C NMR signals associated with these branches indicate that there are about 1-2 ethyl groups per 100 monomer units. As a consequence, the melting temperature is 10-15 °C lower than the linear polyethylene obtained with the rac mixture of the same zirconocene complex. On the basis of kinetic evidence, a branching mechanism that involves a beta-H transfer to the coordinated ethylene is proposed.

Branched Polyethylene by Ethylene Homopolymerization with meso-Zirconocene Catalyst

IZZO, Lorella;CAPORASO, Lucia;OLIVA, Leone
1999

Abstract

The polyethylene obtained in the presence of the catalyst constituted by the meso isomer of the prototypical zirconocene complex (ethylene)bis(1-indenyl)zirconium dichloride activated by methylalumoxane is characterized by the presence of ethyl branches. The intensities of the 13C NMR signals associated with these branches indicate that there are about 1-2 ethyl groups per 100 monomer units. As a consequence, the melting temperature is 10-15 °C lower than the linear polyethylene obtained with the rac mixture of the same zirconocene complex. On the basis of kinetic evidence, a branching mechanism that involves a beta-H transfer to the coordinated ethylene is proposed.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11386/1060851
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