Effect of alkylaluminum structure on Ziegler-Natta catalyst systems based on neodymium for producing high-cis polybutadiene |
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Authors: | Tereza C J Rocha Fernanda M B Coutinho Bluma G Soares |
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Affiliation: | 1.Instituto de Macromoléculas Professora Eloisa Mano,Universidade Federal do Rio de Janeiro,Rio de Janeiro,Brasil;2.Departamento de Processos Químicos, IQ/UERJ,Rio de Janeiro,Brasil |
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Abstract: | Summary In this work, a laboratory scale process for producing polybutadiene with high content of cis-1,4 repeating units was studied. A Ziegler-Natta catalyst system constituted of neodymium versatate (catalyst), an alkylaluminum
compound (alkylating agent and cocatalyst) and tert-butyl chloride (chlorinating agent) was used. The solvent employed was
a mixture of hexane and cyclohexane (80/20 v/v). The objective of this work was to evaluate the effect of alkylaluminum structure
and the influence of Al/Nd (5 to 15) molar ratio of long chain alkylaluminium compound (tri(n-hexyl)aluminum) on catalyst
activity and polybutadiene characteristics. The alkylaluminum compounds employed in this study were tri(i-butyl)aluminum,
tri(n-hexyl)aluminum, tri(n-octyl)aluminum and di(i-butyl)aluminum hydride. The polybutadienes molar masses obtained were
strongly influenced by the alkylaluminum structure. Polymers with the highest molar masses were obtained when tri(i-butyl)aluminum,
tri(n-hexyl)aluminum and tri(n-octyl)aluminum were employed. However, polymers with the highest contents of cis-1,4 units and the lowest molar masses were produced when di(i-butyl)aluminum hydride was employed. |
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