Produção Nacional
Revisado por pares
Evaluation of the Initial Stages of Gas‐Phase Ethylene Polymerizations with a SiO 2 ‐Supported Ziegler–Natta Catalyst
2009; Wiley; Volume: 3; Issue: 1 Linguagem: Inglês
10.1002/mren.200800037
ISSN1862-8338
AutoresFabricio Machado, Enrique Luis Lima, José Carlos Pinto, Timothy F. L. McKenna,
Tópico(s)Lanthanide and Transition Metal Complexes
ResumoAbstract The very early stages of gas‐phase ethylene polymerization on an SiO 2 ‐supported Ziegler–Natta catalyst were studied with the help of a short‐stop reactor. The short‐stop‐reactor‐based technique was useful in studying nascent polymerization, providing insights at very short, controlled times into important phenomena regarding catalyst fragmentation and the activation and deactivation of catalyst sites that take place during the very early stages of the reaction. Experimental results indicate that the growth of the polymer chains occurs at unsteady conditions during the initial stages of the polymerization. Hydrogen has a strong influence on the initial kinetics, leading to a significant decrease of polymerization activity. Polymer crystallinity increases with the reaction time, probably due to the formation of long chains with a high degree of crystallinity. magnified image
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