Results 181 to 190 of about 902,813 (269)

“Oscillating” Metallocene Catalysts:  What Stops the Oscillation?

Journal of the American Chemical Society, 2003
The 150 MHz (13)C NMR microstructural analysis of polypropylene samples produced with two representative "oscillating" metallocene catalysts of largely different steric hindrance, namely [(2-(3,5-di-tert-butyl-4-methoxyphenyl)indenyl)(2)ZrP](+) and [(2-phenylindenyl)(2)ZrP](+) (P = polymeryl), and the implications on the origin of the stereocontrol are
BUSICO, VINCENZO, Van Axel Castelli Valeria, Aprea Paola, CIPULLO, ROBERTA, Segre Annalaura, TALARICO, GIOVANNI, VACATELLO, MICHELE   +6 more
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Metallocene and Ziegler-Natta Catalysts

2021
Fifty years ago, Karl Ziegler and Natta won the Nobel Prize for their discovery of the catalytic polymerization of ethylene and propylene using titanium compounds with aluminum-alkyls as co-catalysts. Polyolefins are constantly growing and are now one of the most important highconsumption polymers. New metallocene/methylaluminoxane (MAO) catalysts have
Vinod Vishwakarma, Sandeep, Kulkarni, S.G.   +1 more
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Heterogeneous Metallocene Catalysts

1995
Copolymerizations of olefins were carried out with the SiO2-, AI2O3- and MgCl2-supported Et[IndH4]2ZrCl2 catalysts combined with AIR3 as cocatalyst and the results were compared with those obtained previously in the presence of homogeneous Et[IndH4]2ZrCl2-MAO catalyst.
Kazuo Soga, Manabu Kaminaka, Hyun Joon Kim, Takeshi Shiono   +3 more
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Olefin copolymerization with metallocene catalysts. III. Supported metallocene/methylaluminoxane catalyst for olefin copolymerization

Journal of Polymer Science Part A: Polymer Chemistry, 1991
AbstractSupported catalyst for fluidized bed polymerization processes has been prepared by reacting macroporous SiO2 first with MAO (methylaluminoxane) and then with Et [Ind]2ZrCl2. It contains 0.60 wt % of Zr and an [Al]/[Zr] ratio of 50. This catalyst produces homogeneous E/P (ethylene/propylene) copolymers with truly random copolymerization ...
James C. W. Chien, Dawei He
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Polymerization reaction engineering — Metallocene catalysts

Progress in Polymer Science, 1996
Abstract Metallocene catalysts are operative in all existing industrial plants that are presently used for polyolefin manufacture and have the potential to revolutionize the technology for the production of these polymers. A review of metallocene catalysis and its effects on polymer process engineering for the manufacture of polyolefins is provided ...
Archie E. Hamielec, Joao B.P. Soares
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Metallocene catalysts for olefin polymerization

Coordination Chemistry Reviews, 1999
Abstract The discovery of metallocene methylaluminoxane (MAO) catalysts has opened a frontier in the area of organometallic chemistry, polymer synthesis and processing. A great number of different titanocenes and zirconocenes have been synthesized that give tailored polymers of totally different structures, let control polymer tacticity, molecular ...
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Heterogenization of Metallocene Catalysts for Alkene Polymerization

Angewandte Chemie International Edition, 1999
Beyond mere convenience: In large-scale industrial processes for alkene polymerization the essentially homogeneous metallocene/activator catalyst systems are heterogenized (example shown) to improve polymer properties. New mesoporous and organic catalyst supports and their application in this field of catalysis are described.
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Metallocene Catalysts for Olefin Oligomerization

Macromolecular Symposia, 2006
AbstractMetallocene complexes with a cocatalyst such as methylalumoxane, MAO can be used as catalysts in the dimerization or oligomerization of olefins (alkenes) including the (co‐/hydro‐)oligomerization of ethene, of the α‐olefins propene, 1‐butene, 1‐pentene, 1‐hexene, and higher α‐olefins, branched α‐olefins, cyclic olefins and α,ω‐dienes.
Janiak, Christoph, Blank, Jan-Frederik
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Metallocene catalysts technology and environment

Comptes Rendus de l'Académie des Sciences - Series IIC - Chemistry, 2000
Abstract The polyolefin industry is increasingly confronted with the challenge to meet restricting environmental regulations. In parallel, the environmentally conscious public opinion (customer!), now globally organized, demands even more stringent anticipative actions to prevent any short or long term damages inflicted upon environment.
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Polymerization of propene by post‐metallocene catalysts

Macromolecular Symposia, 2004
AbstractIn the last few years several non‐metallocene catalysts have been disclosed as efficient catalysts for the stereospecific polymerization of propene.In this paper we summarize some recent literature data and some new results concerning the stereochemical mechanism of propene polymerization promoted by late transition metal systems and group 4 ...
LAMBERTI, Marina, MAZZEO, Mina, PAPPALARDO D, ZAMBELLI A, PELLECCHIA, Claudio   +4 more
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