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Polímeros

versão impressa ISSN 0104-1428versão On-line ISSN 1678-5169

Resumo

ROCHA, Tereza C. J.; SOARES, Bluma G.; COUTINHO, Fernanda M. B.  e  COSTA, Marcos A. S.. Effect of electron donors on the polymerization of butadiene with Ziegler-Natta catalysts based on neodymium. Polímeros [online]. 2005, vol.15, n.1, pp.39-45. ISSN 1678-5169.  https://doi.org/10.1590/S0104-14282005000100010.

A laboratory scale process for producing polybutadiene with high content of cis-1,4 repeating units was studied. A Ziegler-Natta catalytic system constituted of neodymium versatate (catalyst), diisobutylaluminium hydride (cocatalyst) and tert-butyl chloride (chlorinating agent) was used. The solvent employed was a mixture of hexane and cyclohexane (80/20 v/v). The effect of two electron donors, tetrahydrofuran (THF) and tetramethylethylenediamine (TMEDA), was studied. The electron donors were added to the polymerization medium and/or to the solvent employed in the catalyst preparation. The proportion of electron donors was varied between 20 and 200 ppm for THF and between 0 and 15 ppm for TMEDA. The influence of electron donors on the stereoselectivity, catalytic activity, molar mass and molar mass distribution of polybutadiene was evaluated. The polymers were characterized by infrared spectroscopy, size exclusion chromatography and differential scanning calorimetry. Polymers with cis-1,4 units content varying between 99.2% and 93% were produced. The weight-average molar mass, , varied from 2.2 to 7.0x105. The polymers glass transition temperature was kept around -110ºC.

Palavras-chave : High cis-1,4 polybutadiene; Ziegler-Natta catalyst; electron donors.

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