Tandem Action of TpMsNiCl and Supported Cp2ZrCl2 Catalysts for the Production of Linear Low‐Density Polyethylene

Abstract

AbstractSummary: 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 TpMsNiCl (TpMs = hydridotris(3‐mesitylpyrazol‐1‐yl) and Cp2ZrCl2/SMAO‐4, by varying the nickel loading mole fraction (xNi). 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 xNi as well as by the temperature of polymerization, affording the copolymers with a melting point (Tm) between 118 and 135 °C. The GPC results show that the molecular weight ($\overline M _{\rm w}$) of the polymers is sensitive to the xNi. 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 xNi 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.imageOverview of the copolymerization process, from ethylene in the presence of MAO, mediated by catalysts 1 and 2/SMAO.