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Polímeros

versão impressa ISSN 0104-1428

Resumo

PIRES, Neusa Maria Tocchetto et al. Evaluation of Cl/Nd and Al/Nd molar ratios in the polymerization of 1,3-butadiene with the catalyst system comprising neodymium versatate/ di-isobutylaluminium hydride /t-butyl chloride. Polímeros [online]. 2014, vol.24, n.3, pp.314-323.  Epub 18-Abr-2014. ISSN 0104-1428.  https://doi.org/10.4322/polimeros.2014.018.

This work studied ternary catalyst systems composed of neodymium versatate, t-butyl chloride and diisobutylaluminium hydride used in the cis-1,4 polymerization of butadiene in hexane. The effect of Cl/Nd and Al/Nd molar ratios on the polymerization was investigated. The polymers were characterized by size exclusion chromatography (SEC), Fourier transform infrared spectroscopy (FT-IR) and viscosimetry in melted-state. The catalytic activity, molecular weight, molecular weight distribution and Mooney viscosity were strongly influenced by the Cl/Nd molar ratio. The highest cis contents were observed at Cl/Nd molar ratio > 3. The maximum of catalytic activity was obtained at Cl/Nd molar ratios between 3 and 5. The microstructure of polybutadiene was significantly influenced by the increase in the Al/Nd molar ratio. The maximum value, 99% of cis content, was observed for the Al/Nd molar ratio = 10. The conversion data versus reaction time showed that the rate of polymerization increases with the Al/Nd molar ratio reaching a maximum in Al/Nd = 23. The molecular weight distribution curves showed a significant chain transfer process for polymers produced at higher Al/Nd molar ratios.

Palavras-chave : Ziegler-Natta catalyst; neodymium; t-butyl chloride; diisobutylaluminium hydride; polybutadiene.

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