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Molecular weight and molecular weight distribution of polyethene obtained with rac ‐Me 2 Si(Ind) 2 ZrCl 2 /methylaluminoxane
Author(s) -
Naga Naofumi,
Mizunuma Kooji
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(19980101)199:1<113::aid-macp113>3.0.co;2-6
Subject(s) - methylaluminoxane , molar mass distribution , polymerization , polymer chemistry , toluene , propene , chemistry , solvent , catalysis , mass fraction , molecular mass , metallocene , organic chemistry , polymer , enzyme
Ethene and propene polymerizations were carried out with the rac ‐Me 2 Si(Ind) 2 ZrCl 2 (Me = CH 3 , Ind = indenyl)/methylaluminoxane (MAO) catalyst in toluene. The molecular mass distribution index (MMD = M̄ w /M̄ n ) of polypropenes was almost 2,0, while a bimodal MMD was observed for polyethene. The MMD of polyethene was independent of the [Al]/[Zr] ratio and the [Zr] concentration. However, the high molecular weight fraction disappeared when the polymerization was performed either at a low temperature or by using dry MAO. Addition of AlMe 3 to the MAO caused an increase of the low molecular weight fraction at the initial stage of polymerization. The low molecular weight fraction was also increased when the polymerization was conducted in a mixture of toluene and CH 2 Cl 2 as the solvent. From these results, the active species formed in the catalyst system are discussed.