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Tandem Action of Tp Ms NiCl and Supported Cp 2 ZrCl 2 Catalysts for the Production of Linear Low‐Density Polyethylene
Author(s) -
Kuhn Maria Cristina A.,
da Silva Jaqueline L.,
Casagrande Adriana C. A.,
Mauler Raquel S.,
Casagrande Osvaldo L.
Publication year - 2006
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/macp.200600043
Subject(s) - methylaluminoxane , polymer chemistry , linear low density polyethylene , copolymer , ethylene , polyethylene , monomer , polymerization , catalysis , branching (polymer chemistry) , polymer , materials science , melting point , molar mass distribution , dynamic mechanical analysis , chemistry , metallocene , organic chemistry , composite material
Summary: Linear low‐density polyethylene (LLDPE) samples with different properties were prepared from ethylene, without the addition of an α ‐olefin co‐monomer, using a combination of the catalyst precursors Tp Ms NiCl (Tp Ms = hydridotris(3‐mesitylpyrazol‐1‐yl) and Cp 2 ZrCl 2 /SMAO‐4, by varying the nickel loading mole fraction ( x Ni ). Upon activation with methylaluminoxane (MAO), this binary catalytic system showed activities varying from 12.3 to 309.1 kg of PE · (mol[M] · atm · h) −1 . The properties of the polymeric materials are influenced by x Ni as well as by the temperature of polymerization, affording the copolymers with a melting point ( T m ) between 118 and 135 °C. The GPC results show that the molecular weight ( $\overline M _{\rm w}$ ) of the polymers is sensitive to the x Ni . In all of the cases studied, the GPC curves displayed monomodal molecular weight distributions (MWDs) with the average molecular weight varying from 30 000 to 507 000 g · mol −1 . Studies using dynamic mechanical thermal analysis (DMTA) show that the formation of different polymeric materials is associated with the branching content, with the stiffness varying according to the x Ni and the temperature used in the polymerization reaction.Overview of the copolymerization process, from ethylene in the presence of MAO, mediated by catalysts 1 and 2 /SMAO.