Search results for " Natta"
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Quantification of poisons for Ziegler Natta catalysts and effects on the production of polypropylene by gas chromatographic with simultaneous detecti…
2020
[EN] This article describes a new simultaneous method for the analysis of sulfur-type poisons, hydrocarbons and permanent gases affecting the productivity of the Ziegler Natta catalyst during the synthesis of polypropylene on an industrial scale in a fluidized-bed reactor. The identification was achieved employing a configuration of the seven-valve chromatographic system, with events at different times, allowing distribution of the sample through multiple columns, and finally reaching the helium ionization detectors of pulsed discharge, flame ionization and mass spectrometry. The results obtained show a good precision of the method used because the variability was less than 1.02% in area an…
L’opera del premio Nobel Giulio Natta fra le attività della Società Italiana per il Progresso delle Scienze (SIPS) e della Società Chimica Italiana (…
2013
In spite of its great historical and social-institutional importance, the Italian Society for the Progress of Sciences (SIPS) still have not that historical fame which it would deserve. This paper wishes to contribute to delineate a brief historic-critical account which may provide a coherent diachronic perspective in which historically laid out such an institution, highlighting the relevant load that it has had for the cultural, scientific and technological development of the post-Resurgence Italy. From this historical recognition, it will be then possible to descry a more or less direct role played by SIPS, around the first half of 20th Century, as concerns the research activity of the It…
Synthesis and catalytic properties for olefin polymerization of new vanadium complexes containing silsesquioxane ligands with different denticity
2017
A series of new vanadium-silsesquioxanes (2a − 2d) was prepared by reacting VCl4 with not fully condensed silsesquioxanes (having from one to four silanol groups) and evaluated as pre-catalysts in olefin polymerization. The activation of 2a − 2d with EtAlCl2 generated highly active catalysts for ethylene polymerization, yielding high molar mass polymers with narrow dispersity. Ultra-high molar mass polyethylenes, Mw up to 4 × 106 g mol−1, were obtained with methylaluminoxane and Al(iBu)3/[Ph3C][B(C6F5)4] as activators. Upon treatment with methylaluminoxane and boron compounds, all vanadium pre-catalysts were active in 1-octene polymerization as well, and produced isotactic-rich poly(1-octen…