Multiblock Microstructure Using a Binary System of Metallocene Catalysts with Diethyl Zinc as Transfer Agent

Leticia Pereira, Roberto Martins and Maria Marques
Universidade Federal do Rio de Janeiro, Instituto de Macromoleculas Eloisa Mano, IMA-UFRJ. Cidade Universitaria. Av. Horacio Macedo, 2.030. Centro de Tecnologia. Bloco J. Rio de Janeiro. RJ. Brasil;
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The aim of this study was to synthesize ethylene-hexene copolymers of the type LLDPE using a combination of metallocene binary catalysts (Cat 1: Cp2ZrCl2 and Cat 2: Et(IndH4)2ZrCl2), where each catalyst has different microstructural control capacities. The effect of diethyl zinc (DEZ) concentration as a chain shuttling agent (CSA) was evaluated in parameters such as catalytic activity, as well as thermal properties, comonomer content incorporated into the polymer chain, crystal structure, and also dynamic mechanical properties of the obtained copolymers. The results showed that, opposite to the behavior of the catalyst mixtures, DEZ promoted an increase in the polymerization activity with the isolated catalysts. Furthermore, CSA provided the increase of the rigid segments in the copolymer chain obtained with the binary catalyst.

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