Search results for "Natta"
showing 10 items of 76 documents
The roles for a Lewis base and MgCl2 in third-generation Ziegler-Natta catalysts
1998
Activity of a titanium catalyst supported on a bimetallic magnesium-aluminium system, involving a Lewis base [MgCl2(THF) 2 /Al(C 2 H 5 ) 2 Cl], was studied in ethylene polymerization, and the effect of the catalyst composition on the properties of the final polymer produced was investigated. Analysis and discussion of the findings covering also some part of the kinetic study, resulted in defining the roles for MgCl 2 and a Lewis base in the third-generation Ziegler-Natta catalysts. MgCl 2 forms a bimetallic complex with an organoaluminium compound, which involves also a Lewis base. Its reaction with TiCl 4 yields a very active catalyst wherein the Mg: Ti molar ratio is close to 1. This mean…
Oxovanadium(IV) complexes with [ONNO]-chelating ligands as catalysts for ethylene homo- and copolymerization
2014
Oxovanadium(IV) complexes with (ONNO)-type tetradentate Schiff base ligands: salen, acacen, aceten, acetph (H2salen = N,N'-ethylenebis(salicylideneimine), H2aceten = N,N'-ethylenebis(2-hydroxyacetophenoneimine), H2acacen = N,N'-ethylenebis(acetylacetonimine), H 2 acetph = N ,N ' -phenylene-1,2-b is (2-hydroxyacetophenoneimine)), were the first time investi- gated in ethylene polymerization and ethylene/1-octene copo- lymerization processes. In general, all these complexes are moderately active precatalyst for ethylene polymerization up- on activation with EtAlCl2 and they give high molecular weight linear polyethylenes. Their activity in copolymeriza- tion was found relatively low. However,…
Ethylene homo- and copolymerization catalyzed by vanadium, zirconium, and titanium complexes having potentially tridentate Schiff base ligands
2021
Abstract New potentially tridentate Schiff base ligands, 2-[({4-[(3-N,N-dimethylamino)propyl] phenyl}imino)methyl]-4,6-di-tert-butylphenol (L1H) and 2-[{2-(N-phenyl-N-methylaminomethyl)-phenylimino}-methyl]-4,6-di-tert-butylophenol (L2H) were prepared and after deprotonation they were reacted with VOCl3 or MCl4 (where M = Zr or Ti) to produce corresponding complexes (L1-V, L2-V, L1-Zr, L2-Ti) with good yields. All new compounds were characterized by the 1H and 13C NMR as well as FTIR spectroscopic methods. Upon activation with Et2AlCl or EtAlCl2, both the vanadium complexes exhibited exceptionally high catalytic activities in the ethylene polymerization (up to 69,000 kg/(molV⋅h) for L1-V an…
Perheyritykset kansantalouden resurssina : keskisuurten ja suurten yritysten omistajuus, toiminnan laajuus ja kannattavuus Suomessa 2000-2005
2009
The first main goal of the research is family business contribution analysis, anexamination of the economic effect of family businesses in Finland. Another topic ofinterest is the relationship between the type of ownership and financial performance ofthe firm, a comparison analysis of profitability between family and non-familybusinesses.On a world-wide basis, the contribution of family businesses to nationaleconomies is considerable. However, the exact extent of the impact of familybusinesses has remained unknown. One reason for this problem is the fact that thereare neither official statistics nor representative performance data available of familybusinesses at the national economic level…
A comparative study on the polymerization of 1-octene promoted by vanadium and titanium complexes supported by phenoxyimine and salen type ligands
2013
Polymerizations of 1-octene were carried out in the presence of vanadium and titanium complexes bearing salen-type or phenoxyimine ligands activated with various co-catalysts. Vanadium complexes turned out active only in conjunction with MAO, whereas the titanium ones were active in combination with Al(i-Bu)3/Ph3CB(C6F5)4. The activity of all catalysts was moderate or low and it was dependent on the ligand type: bis(phenoxyimine) complexes were more active than the salen ones. Both vanadium and titanium catalytic systems produced poly(1-octene)s possessing atactic structures with [mmmm] sequences in the range from 12 to 56 % at room temperature. A temperature decrease to 0.5 °C for the reac…
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…
Kustannuslaskenta ja avoin hinnoittelu lisäarvoa tuottavana palveluna molemmin puolin monopolistisessa partnerisuhteessa
2017
Tässä tutkimuksessa toteutetaan, mitataan, tarkastellaan ja arvioidaan toimintolaskentaa ja kustannuksiin perustuvaa kokonaan nimikekohtaisesti avointa hinnoittelupolitiikkaa lisäarvoa tuovana palveluna pitkäaikaisissa liiketoimintasuhteissa. Tutkimuksen pohjaksi rakennetaan laaja-alaisesti sovellettavaa teoriaa niin toimintolaskennasta, liikeaika-analyyseistä, verkostoteoriasta kuin peliteoriastakin. Case-tutkimuksen käytännön osuudessa analysoidaan, mitä haasteita on toimintolaskennan toteutuksessa ja sen pohjalle perustuvan hinnoittelumallin luonnissa ja sopimisessa, millaisia pitkän ja lyhyen aikavälin haasteita ja intressiristiriitoja malleihin helposti sisältyy sekä esitetään, miten j…
Rola chlorku magnezu jako nośnika katalizatorów Zieglera-Natty
2000
Structural examination data are presented for various supports. Porosimetry (Table 2) and particle size distribution studies on MgCl 2, MgCl 2(THF) 2, Al 2O 3 as supports, carried out prior to and after ball-milling (Figs. 1, 3), suggest that MgCl 2 is beneficial as carrier because it is more liable to pretreatment (ball-milling, presence of a Lewis base) and allows its mass to be better utilized and its surface to produce catalytically active centers. Prolonged ball-milling of MgCl 2 was found to result not only in comminuted particles but also in increased specific area and larger pore volume. Studies on synthesis conditions of a vanadium precursor supported on MgCl 2(THF) 2 showed prolon…
Maatilayritysbarometri : tutkimusraportti
2012
Maatilayritysbarometrin 2012 tarkoituksena on herättää keskustelua maaseudusta maatilayritysten toimintaympäristönä ja maatilayritysten tulevaisuuden odotuksista. Barometrin tavoitteena on tuottaa virikkeitä maaseutustrategiseen keskusteluun ja tietoa maaseudun kehittämis- ja ohjelmatyölle. Barometrin teemat voidaan pukea kysymysten muotoon: Millainen on keskisuomalaisten maatilayrittäjien suhde maaseutuun? Miten maatilayrittäjät näkevät Keski-Suomen maaseudun vuonna 2016? Miten maatilayrittäjät arvioivat maatilayrityksen liiketoimintaympäristön tulevaisuuden kehitystä ja tulevaisuuden kehitysnäkymiä? Entä miten he arvioivat toimintaedellytysten parantamista ja liiketoiminnan edellytyksiä K…
Novel diamine-bis(phenolate) Ti(IV) complexes – tuning the complex structure to control catalytic properties in α-olefin polymerization
2016
Abstract Four monomeric titanium(IV) dichloride complexes of amine-bis(phenolate) ligands having an extra donor arm (2a–2d) and one oxo-bridged complex 3 were successfully synthesized in the reaction of TiCl4 with a sodium salt of the appropriate ligand, and they were characterized by 1H NMR spectroscopy. The ligands had either a dimethylamino side‐arm donor and t-Bu substituents on both (1a) and one (1d) phenolate rings or a diisopropylamino side-arm donor and t-Bu (1b) and t-Bu along with OMe (1c) phenolate substituents. All complexes upon activation with [Ph3CB(C6F5)4] and MAO were used to catalyze polymerization of 1-octene (in liquid monomer) into poly(1-octene). Their activities as we…