Tandem Action of Tp^MsNiCl and Supported Cp₂ZrCl₂ Catalysts for the Production of Linear Low‐Density Polyethylene

Abstract

Abstract 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. image Overview of the copolymerization process, from ethylene in the presence of MAO, mediated by catalysts 1 and 2 /SMAO.