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