LLDPE with Exclusively Ethyl Branches by Tandem Catalysis with Single-Site Zr(IV)/Co(II) Catalysts |
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Authors: | Claudio Bianchini Giuliano Giambastiani Andrea Meli Itzel Guerrero Rios Alessandro Toti Elisa Passaglia Marco Frediani |
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Affiliation: | 1. ICCOM-CNR, Area della Ricerca CNR di Firenze, via Madonna del Piano 10, 50019, Sesto Fiorentino, Italy 2. ICCOM-CNR, section of Pisa, c/o Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via Risorgimento 35, 56126, Pisa, Italy 3. Dipartimento di Chimica Organica, Università di Firenze, Polo Scientifico, via della Lastruccia 13, 50019, Sesto Fiorentino, Italy
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Abstract: | Semicrystalline linear low density polyethylenes (LLDPEs) with exclusively ethyl branching (from 7 to 56 branches per 1,000 carbon atoms) were prepared from ethylene by homogeneous tandem catalytic systems comprising (imino)pyridine cobalt(II) dichlorides as oligomerization precursors, bis(cyclopentadienyl)zirconium(IV) dichloride as copolymerization precursor and methyaluminoxane as activator. The activity of the tandem systems was evaluated by varying either the molar fraction of the cobalt precursors or the ethylene pressure. The latter parameter was of crucial importance to control both the productivity and the extent of 1-butene incorporation. In particular, increasing the ethylene pressure from 2 bar to 4 bar changed the “comonomer effect” from positive to negative. |
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