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Showing 1 to 20 of 29 for “"Ziegler-Natta"”.
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Investigation of polymer grade blending in Ziegler-Natta Catalysed ethylene polymerisation systems
… operate on technology involving heterogeneous Ziegler-Natta catalysts. Plants often change operating conditions to produce different polymer grades; this allows them to cater to a larger polymer market. A side-effect of this practice is the unwanted formation of off-spec polymer during the …
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Organometallic Group 4 bis(borylamide) complexes as templates for Ziegler-Natta catalysis
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1997.
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Chelating polyamido complexes or rhenium, molybdenum, and hafnium : organometallic synthesis to Ziegler-Natta catalysis
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1998.
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Early transition metal complexes containing tridentate amido ligands : a systematic approach to Ziegler-Natta catalysis
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1999.
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Examination of Dynamic Processes in Living Ziegler-Natta Polymerization and New Polypropylene Architectures through Bimolecular Control
The cationic cyclopentadienyl zirconium acetamidinate (CPZA) complex {Cp*ZrMe[N(Et)C(Me)N(tBu)]}[B(Csub6 Fsub5)sub4], (Cp* = ηsup5-Csub5Mesub5) generated through activation of Cp*ZrMesub2[N(Et)C(Me)N(tBu)] via protonolysis of a methyl group with one equivalent of [PhNMesub2H][B(Csub6Fsub5)sub4], …
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Development of a computationally efficient model for the control of Ziegler-Natta catalysed industrial production of high density polyethylene
… alkenes, using heterogeneous titanium-based Ziegler-Natta catalysts. During grade transitions, when reactor conditions are manipulated to change polymer properties, significant quantities of off-specification product result. Implementing a model-predictive controller based on a dynamic …
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Avaliação das propriedades do polietileno de alta densidade produzido com catalisador Ziegler-Natta submetido à estrusão reativa com peróxidos orgânicos
… amostras de pó de PEAD produzido com catalisador Ziegler-Natta, para utilização em processamento por injeção, sopro ou extrusão de filmes, foram extrusadas com o peróxido de dicumila e o 2,5-dimetil-2,5-di(t-butilperoxi)-hexano em teores de 0,001 a 0,08 pcp. Os produtos obtidos foram …
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Polyenes by regioselective, living polymerization using molybdenum alkylidene bis(carboxylate) initiators and Ziegler-natta catalysis employing new zirconium diamido complexes
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1997.
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Observation of the first titanium alkyl/alkyl complexes: The key intermediate in the Ziegler-Natta mechanism for the polymerization of alkenes
… intermediate in the Cossee mechanism for Ziegler-Natta catalysis. Above $-$20$\sp\circ$C, the TiX$\sb2$(dmpe)$\sb2$ complexes catalyze the dimerization of ethylene to 1-butene with turnover rates of up to 440 hr$\sp{-1};$ the rates of ethylene dimerization vary according to the nature of …
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Early transition metal catalysts for the living polymerization of olefins and alkynes
Zirconium and Hafnium Ziegler-Natta catalysts containing the [(2,6- C12C6H3NCH2CH2)2NMe]2- ([ArciN2NMe]2') ligand were prepared and employed in the polymerization of 1-hexene. Hafnium Ziegler-Natta catalysts containing the [(2,6- X2C6H3NHCH2)2C(CH3)(2-C5H4N)] ([Arx2NPy]2-) (X = Cl or F) ligand were …
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Studies of carbon-hydrogen and silicon-hydrogen bond activation by early transition metal complexes
… as catalysts for olefin polymerization in the Ziegler-Natta and Phillips processes. The key intermediates in these catalysts are thought to be six-coordinate metal alkyl/olefin complexes. The synthesis and study of early transition metal alkyl complexes as models of these catalytic centers can …
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The chemistry of manganese alkyls and aryls and of divalent titanium phenoxides
… oxidations by manganese-containing complexes and Ziegler-Natta olefin polymerizations, respectively.
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Koordinationschemische Untersuchungen zur syndiotaktischen Polymerisation von Styrol
… von Styrol unter Verwendung von diesen homogenen Ziegler-Natta-Katalysatoren beigetragen. Im Rahmen dieser Arbeit wurden neuartige Katalysatoren zur Gewinnung von syndiotaktischem Styrol entwickelt. Dazu wurden einerseits besonders raumfüllende Liganden vom Cyclopentadienyltyp, aber auch …
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Thermorheology and processing of polyethylene blends : macromolecular structure effects
… of blends prepared and studied consisted of two Ziegler-Natta LLDPE's (LL3001.32 and Dowlex2045G) and two metallocene LLDPE's(AffinityPL1840 and Exact 3128) blended with a single LDPE. In DSC melting thermograms, it was observed that blends with metallocence LLDPE's exhibit a single melting peak …
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[1]- und [2]Borametallocenophane der Gruppe-4-Metalle : Synthese, Struktur und katalytische Aktivität
… berichtet, die als Katalysatoren in der Ziegler-Natta-artigen Olefinpolymerisation eingesetzt werden können. Neben den bereits bekannten [1]Borametallocenophanen wurden weitere Komplexe mit unterschiedlichen Substituenten, als auch die bislang unbekannten [2]Borametallocenophane …
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Predictive Modeling of Metal-Catalyzed Polyolefin Processes
… large-scale commercial processes involving the Ziegler-Natta polymerization to produce high-density polyethylene (HDPE) and polypropylene (PP). It also provides a model for the solution polymerization of ethylene using a metallocene catalyst. Existing modeling efforts do not include physical …
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The Synthesis, Characterisation and Electrical Conductivity of Poly(Styrene-Co-Acetylene)
… oligomers (polyenes) by modifying the Ziegler/Natta type catalysts commonly used to synthesise polyacetylene. The polyenes were characterised using U.V./Visible and infra-red spectroscopy together with GPC and GCMS.
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Organometallic Polymerization Catalysts
… of styrene initiated by vanadium-based Ziegler-Natta catalysts, the most active of which was formed from VOC1₃/A1Et1.5Cl1.5 and was the most active also for the copolymerization of ethylene and propylene. A dilatometric study of the polymerization, using a device that could be filled …
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