Griselda Ligia Barrera Galland

ESTUDIO DE LA POLIMERIZACION DE PROPENO UTILIZANDO DIFERENTES CATALIZADORES METALOCENOS

En este trabajo se reporta el estudio de la polimerizacion de propeno utilizando los catalizadores metalocenos: dicloruro de etilenbisindenil circonio IV racemico, rac-Et(Ind)2ZrCl2 (I); dicloruro de etilenbis(2-metil-indenil) circonio IV racemico, rac-Et(2-Me-Ind)2ZrCl2 (II); dicloruro de dimetilsililbisindenil circonio IV racemico, rac-Me2Si(Ind)2ZrCl2 (III) y dicloruro de difenilmetilindeno ciclopentadienil 9-fluorenil circonio IV, Ph2C(Flu)(Cp)ZrCl2 (IV) en presencia de metilaluminoxano (MAO) como cocatalizador. Las polimerizaciones fueron realizadas a diferentes condiciones de temperatura, concentracion de catalizador, razon molar cocatalizador/catalizador y concentracion de monomero. Este estudio fue elaborado con la ayuda de un modelo estadistico de planeamiento experimental. Se observo que tanto el tipo de catalizador, como las condiciones de reaccion estudiadas tienen una influencia en la actividad catalitica y en las propiedades de los polimeros obtenidos. Valores elevados de actividad fueron encontrados con los catalizadores I y III a una temperatura de polimerizacion de 70 C. Con el catalizador III se obtuvieron los polipropilenos de mayor isotacticidad. El catalizador IV produjo polimeros sindiotacticos

Influência da estrutura de diferentes copolímeros de etileno e a-olefinas na funcionalização com anidrido maleico

Chemical modification of ethylene a-olefins copolymers with maleic anhydride was studied by radical reaction in solution, melt mixing and extrusion. The effect of copolymer structure, as the amount and length of the branches, was evaluated on the MA incorporation. The reactions were also achieved in Rheomix 600 (Haake) mixer and Rheocord 9000 (Haake) extruder. Functionalization was determinated by titration and modified ethylene a-olefins copolymers were characterized by Infrared Spectroscopy and Gel Permeation Chromatography. The maleic anhydride incorporation in the ethylene-hexene copolymers increases with the amount of a-olefin. Functionalization of ethylene-octene and ethylene-decene comonomers increases with increasing peroxide concentration until a maximum and then decreases up to a constant value.

New Isopropylmaltol - Ti Synthesis and its Use as a Catalyst for Olefin Polymerization

This report describes a new synthesis of isopropylmaltol from furfural. This organic compound was used as ligand to obtain a new complex, the dichlorobis-(3-hydroxy-2-isopropyl-4-pyrone) titanium(IV). 1H nuclear magnetic ressonance, elemental analysis and UV-Vis analysis confirm the complex formation. This complex was investigated in ethylene polymerization using methylaluminoxane (MAO) as cocatalyst. The catalytic activity was low, however, there were obtained very high molecular weight polyethylenes, which are interesting for various special applications.

Análise de copolímeros de etileno alfa-olefinas por meio de técnicas de fracionamento

Samples of ethylene 1-butene copolymer, produced in laboratory by different processes using Ziegler-Natta catalysts, ethylene-1-hexene and metallocene catalysts, were fractionated according to molecular size by direct extraction by different solvents and at different temperatures. These samples were also fractionated by differences on crystallinity using a DSC calorimeter. The obtained fractions were characterized by 13C-NMR , FTIR, GPC and DSC. The polyethylene copolymers produced by Ziegler-Natta catalyst were found more heterogeneous when compared with the one produced by metallocene catalysts. The commercial resin produced by UCC process with Ziegler-Natta catalysts showed a more homogeneous incorporation of comonomer compared with the one obtained by the Spherilene process. The supported metallocene catalyst gave a more homogeneous product than the homogeneous metallocene one.