Produção Nacional
Revisado por pares
Characterization and evaluation of supported rac ‐dimethylsilylenebis(indenyl)zirconium dichloride on ethylene polymerization
2009; Wiley; Volume: 112; Issue: 1 Linguagem: Inglês
10.1002/app.29430
ISSN1097-4628
AutoresFernando C. Franceschini, Tatiana T. da R. Tavares, Daniela Bianchini, Maria do Carmo Martins Alves, Marı́a Luján Ferreira, João Henrique Zimnoch dos Santos,
Tópico(s)Silicone and Siloxane Chemistry
ResumoAbstract rac ‐Dimethylsilylenebis(indenyl)zirconium dichloride was grafted onto commercial methyl aluminoxane modified silica (SMAO) at different loadings (0.1–1.5 wt % Zr/SMAO). Supported catalysts were evaluated in ethylene polymerization with isoprenylaluminum as a cocatalyst. The characterization of two supported catalysts bearing 0.3 and 0.8 wt % Zr/SiO 2 by extended X‐ray absorption fine structure indicated that the number and the intensity of the peaks beyond the coordination shell, associated with the next nearest neighbors, depended on the Zr concentration. For the catalyst with a higher Zr content, only one peak (2.8 Å) was observed. The catalyst with 0.3 wt % Zr/SMAO presented two small peaks at 2.8 and 3.8 Å. Polymers produced with the supported catalysts presented lower crystallinity and higher molar mass and polydispersity values in comparison to that produced by the homogeneous one. Gel permeation chromatogram deconvolution suggested the presence of four catalyst sites for the supported systems. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
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