Influence of the catalyst and polymerization conditions on the long-chain branching of metallocene-catalyzed polyethenes
作者： Esa Kokko , Anneli Malmberg , Petri Lehmus , Barbro L�fgren , Jukka V. Sepp�l�
DOI: 10.1002/(SICI)1099-0518(20000115)38:2<376::AID-POLA12>3.0.CO;2-5
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摘要: A study was made on the effects of polymerization conditions long-chain branching, molecular weight, and end-group types polyethene produced with metallocene-catalyst systems Et[Ind]2ZrCl2/MAO, Et[IndH4]2ZrCl2/MAO, (n-BuCp)2ZrCl2/MAO. Long-chain branching in polyethenes, as measured by dynamic rheometry, depended heavily catalyst conditions. In a semibatch flow reactor, level polyethenes Et[Ind]2ZrCl2/MAO increased ethene concentration decreased or time increased. The introduction hydrogen comonomer suppressed branching. Under similar conditions, two other systems, (n-BuCp)2ZrCl2/MAO linear only slightly branched polyethene. On basis an analysis FTIR weight GPC, we concluded that chain transfer to prevailing termination mechanism at 80 °C toluene. For β-H elimination dominated low concentrations. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Chem 38: 376–388,
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