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Rio de Janeiro, Brazil

Ferreira Jr. L.C.,Federal University of Rio de Janeiro | De Santa Maria L.C.,State University of Rio de Janeiro | Costa M.A.S.,State University of Rio de Janeiro | Pires N.M.T.,Petroflex Industria and Comercio | And 2 more authors.
Polymer Engineering and Science | Year: 2011

This article is regarding the polymerization of 1,3-butadiene with a neodymium catalyst activated by diisobutylaluminum-hydride and diethylaluminum chloride (DEAC). The effects of the polymerization conditions (ratio between DEAC and neodymium molar concentrations, polymerization temperature, catalyst concentration, and butadiene concentration) on the polymer yield and molecular weight distribution (MWD) of polybutadiene (PB) samples were evaluated. It is shown that the DEAC/Nd ratio and the polymerization temperature are the reaction variables that influence the MWD and the catalyst performance most significantly. PBs with broad and sometimes bimodal MWD were produced at the analyzed reaction conditions. For this reason, the MWD of the obtained polymer materials was deconvoluted with the help of the Flory most probable distribution, indicating that three or more catalyst sites are required to explain the final MWD of the polymer samples. Finally, it was observed that the analyzed neodymium catalyst is able to produce branched PBs at mild reaction conditions and that the branching frequency depends on the polymerization conditions, which may be useful for development of operation policies at plant site and production of materials with improved performances. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers. Source

Simoes A.L.C.,Petroflex Industria and Comercio | Simoes A.L.C.,State University of Rio de Janeiro | Pires N.M.T.,Petroflex Industria and Comercio | De C.B. Dolinsky M.,Petroflex Industria and Comercio | And 2 more authors.
Polimeros | Year: 2011

The rare earth metals catalysts are very efficient in stereospecific polymerization of dienes, especially those of neodymium. This paper reports on the polymerization of 2-methyl, 1,3-butadiene with catalysts of neodymium, used commercially in polymerization of 1,3-butadiene. Effects were studied from the temperature, type of alkylaluminum, and from the concentration of catalyst. The reactions were carried out in a stainless steel reactor under an inert atmosphere, using hexane as the solvent and a concentration of 12% of 2-methyl, 1,3-butadiene. Polymers were obtained with molecular weight from 1.0 to 1.5 × 105, with ca. 97% of cis repeating units. Source

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