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1
Wu, Long. « Ethylene polymerization over morphology-controlled Ziegler-Natta catalysts ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0016/NQ46947.pdf.
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Dai, Shuanghua Patrick. « X-ray scattering and thermal analysis study of isotactic polypropylene / ». Thesis, Connect to Dissertations & ; Theses @ Tufts University, 2000.
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Thesis (Ph.D.)--Tufts University, 2000.Submitted to the Dept. of Physics. Adviser: Peggy Cebe. Includes bibliographical references (leaves 246-251). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
3
Humbert, Matthieu. « Réactivité et Spectroscopies pour caractériser l'effet des acides de Lewis en Catalyse de Polymérisation Ziegler-Natta ». Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1352.
Texte intégralRésumé :
La compréhension de la structure des sites actifs en catalyse Ziegler-Natta de polymérisation des oléfines reste un challenge académique et industriel. Récemment, l’utilisation des acides de Lewis lors de la préparation de catalyseurs Ziegler-Natta a permis d’observer des gains d’activité lors de la polymérisation de l’éthylène (et des α-oléfines). Pour comprendre l’effet bénéfique de ces acides de Lewis, nous avons développé des méthodes spectroscopiques, RMN du solide en particulier, en étudiant les différents noyaux observables au voisinage du centre actif. Dans un premier temps, différents traitements par des acides de Lewis ont été effectués sur un précatalyseur solide Ziegler-Natta natif (TiCl4/MgCl2/bases de Lewis : THF ou EtOH) et représentatif des catalyseurs utilisés dans l’industrie. Ces acides de Lewis augmentent l’activité en polymérisation, en particulier pour BCl3, sans modifier les propriétés physico-chimiques des polymères. En variant les conditions de polymérisation, nous avons pu montrer que l’effet de l’acide de Lewis consistait à révéler de nouveaux sites actifs de même nature que ceux présents à la surface du précatalyseur natif. Dans un deuxième temps, des précatalyseurs Ziegler-Natta traités ou non par BCl3 ont été caractérisés par spectroscopie RMN du solide. La réaction des acides de Lewis avec les bases de Lewis présentes sur le support MgCl2 activé a été mise en évidence. L’étape d’activation par réaction du précatalyseur avec un organométallique de l’aluminium (étape d’alkylation) s’accompagnant d’une réduction du titane (IV) en titane (III), noyau paramagnétique, a également fait l’objet d’une étude spectroscopique des espèces paramagnétiques afin d’observer les précurseurs des sites actifs de polymérisation avant l’ajout d’éthylène. Enfin, dans un contexte plus exploratoire, l’utilisation d’acides de Lewis a été étendue à la catalyse Ziegler-Natta au fer découverte récemment au C2P2. Dans ce cas, un pré-traitement par BCl3 a également été utilisé pour rendre actifs des précatalyseurs FeCl2/MgCl2/base de Lewis n’ayant aucune activité en polymérisation lorsqu’ils sont activés classiquement par des organométalliques de l’aluminium. Des activités en polymérisation se rapprochant d’un précatalyseur Ziegler-Natta classique à base de titane ont été observées. Peu de différences en polymérisation de l’éthylène sont à souligner hormis une excellente activité de ces nouveaux précatalyseurs ferreux à température ambiante (20 °C). L’étude spectroscopique permet de mettre en lumière la complexation du FeCl2 avec le THF à la surface du précatalyseur et le changement de degré d’oxydation du Fer après alkylationThe understanding of active sites structure in Ziegler-Natta catalysis remains academically and industrially challenging. Recently, the use of Lewis acids during the preparation of Ziegler-Natta catalysts has led to activity enhancements in ethylene (and α-olefin) polymerization. Under these optimal activity conditions and to assess the Lewis-acid role, we have developed spectroscopic methods, in particular solid-state-NMR, using different observable nuclei at the active-center vicinity. Various treatments by Lewis acids were first performed on a native and industrially relevant Ziegler-Natta precatalyst (TiCl4/MgCl2/Lewis bases: THF or EtOH). These Lewis acids lead to an increase of activity in polymerization, in particular BCl3, without any modification of polymer properties. By varying polymerization conditions, we have shown that Lewis acid pre-treatments reveal new active sites identical to the ones inherently present at the native precatalyst surface. BCl3 pre-treatment on Ziegler-Natta precatalysts was then monitored by solid-state-NMR spectroscopy. The reaction between Lewis acid and Lewis bases from “activated”-MgCl2 support has been evidenced. The activation step by reaction between precatalyst and an organoaluminium compound (alkylation step accompanied by a reduction of titanium (IV) to paramagnetic titanium (III)), has also been studied by spectroscopic on paramagnetic species in order to observe preactive-site formation in olefin polymerization before ethylene introduction. Finally, in a more exploratory context, BCl3 pre-treatment has been used to activate (FeCl2/MgCl2/Lewis-base: THF) precatalysts, which are originally inactive when contacted with organoaluminium compounds. Activities comparable to titanium-based Ziegler-Natta precatalysts are subsequently observed. No major differences in ethylene polymerization were noticed except that these Iron-based precatalysts retain an excellent activity at room temperature. The spectroscopic study allows to highlight the FeCl2 complexation with THF at the precatalyst surface and the modification of Iron oxidation state after alkylation
4
Bertrand, Pascale. « Modélisation de la polymérisation de l'éthylène par catalyse Ziegler-Natta ». Vandoeuvre-les-Nancy, INPL, 1988. http://www.theses.fr/1988NAN10080.
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Le modèle présenté est fondé sur une approche typique du génie des procédés en ce sens qu'il fait intervenir de pseudo-espèces chimiques représentant le structure du polymère. Les pseudo-espèces chimiques utilisées sont les moments de la distribution des masses moléculaires, le taux de branches courtes, le taux de doubles liaisons et la quantité de polymères produit. Un schéma cinétique faisant intervenir ces espèces est élaboré
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Bierwagen, Erik Paul Goddard William A. Goddard William A. « Computational studies of Ziegler-Natta catalysis and concurrent resonance computations / ». Diss., Pasadena, Calif. : California Institute of Technology, 1995. http://resolver.caltech.edu/CaltechETD:etd-09112007-104050.
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Hajela, Sharad Bercaw John E. « Synthetic, structural, and mechanistic studies of homogeneous Ziegler-Natta catalysis / ». Diss., Pasadena, Calif. : California Institute of Technology, 1995. http://resolver.caltech.edu/CaltechETD:etd-10052007-131102.
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Bertrand, Pascale. « Modélisation de la polymérisation de l'éthylène par catalyse Ziegler-Natta ». Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37611906c.
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Gaschard-Pasquet, Véronique. « Synthèse contrôlée de copolymères éthylène-butène par catalyse Ziegler-Natta bisupportée ». Lyon 1, 1985. http://www.theses.fr/1985LYO10508.
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Les catalyseurs mis au point comportent un double support silice-chlorure de mg qui confere au catalyseur une bonne stabilite granulometrique. La caracterisation des polymeres obtenus montre que ceux-ci sont relativement homogenes et s'approchent de la definition d'un bon "polyethylene basse densite lineaire". Il semble que l'addition d'une base de lewis permette dans certain cas de controler la qualite du produit
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MARTINSKY, CYRIL. « Etude theorique de la reaction de ziegler-natta en catalyse heterogene ». Paris 6, 2000. http://www.theses.fr/2000PA066312.
Texte intégralRésumé :
Ce memoire est dedie a l'etude theorique du catalyseur de ziegler-natta solide. Une etude de la structure et de la reactivite des complexes ticl n, seuls ou couples (dimerisation, addition de ticl n 1ch 3 et complexation avec le chlorure de magnesium), a ete prealablement effectuee. La dimerisation s'effectue par la donation des paires libres du chlore au centre metallique, et on obtient des structures dans lesquelles le chlore se trouve en position pontante entre les deux atomes de titane. Notre etude a egalement montre que le groupement ch 3 pouvait se trouver aussi en position pontante entre les deux metaux, et que ces structures comptaient generalement parmi les plus stables. Ces calculs ont ete realises a l'aide des programmes gaussian 94 et 98. Cette etude preliminaire constitue une base pour l'etude periodique du catalyseur de ziegler-natta solide. Nous avons modelise, a l'aide du programme vasp (vienna ab initio simulation package), la structure des sites actifs, formes par les chlorures de titane, deposes sur les surfaces periodiques du chlorure de magnesium. Les resultats de cette etude periodique valident les structures presentees dans l'etude sur les complexes, et sont en accord avec les mesures experimentales exafs (extended x-ray absorption fine structure). Nous presentons egalement une analyse topologique par la fonction elf (electron localization function) des clusters fe 3(co) 1 2, dans le cadre de l'etude sur la liaison metal-metal. Ce memoire s'acheve par la presentation du programme crysview, developpe au cours de cette these, et visant a la conception et a la manipulation graphique de modeles moleculaires. Ce programme a ete completement acheve et largement utilise dans la realisation des modeles periodiques, s'inscrivant ainsi parfaitement dans le cadre de cette these.
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Gomez-Journaud, Corinne. « Mécanismes de la polymérisation du propylène par catalyse Ziegler-Natta hétérogène ». Lyon 1, 1994. http://www.theses.fr/1994LYO10043.
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L'etude de la catalyse ziegler-natta heterogene supportee sur mgcl#2 a accompagne l'evolution des systemes industriels. J'ai donc voulu dans ce memoire de these reprenant les idees fortes du laboratoire, expliciter differents mecanismes moleculaires comme le modele du site ou l'activation-desactivation du site. Ces etudes nous ont donc amene a proposer un modele de site actif: complexe titane: aluminium ponte qui est chelate par les deux oxygenes d'un dialkoxysilane afin de rigidifier la structure et de controler steriquement l'acces du monomere par encombrement de la lacune du titane par un groupe alkyle encombrant. L'elaboration de catalyseurs preformes a constitue une avancee dans l'obtention de catalyseurs monocomposants performants. L'emploi de silanes utilises industriellement comme le cyclohexylmethyldimethoxysilane nous a permis de montrer la faisabilite d'une telle synthese. Ces catalyseurs ont ete testes dans le propylene liquide et leurs bonnes performances nous ont conforte dans l'idee que nous nous faisons du site actif. Cette premiere partie nous a permis de renforcer notre theorie: la formation du site actif passe par un complexe ternaire aluminium: titane: base de lewis externe. Nous avons alors elabore un schema de site actif qui soit en accord avec le portrait robot que nous avons pu dresser a partir des differentes connaissances acquises. L'outil informatique nous a permis d'obtenir des dessins avec des donnees purement geometriques, ce qui nous a montre la coherence du mecanisme que nous proposons pour le controle de la stereoselectivite. La deuxieme partie de ce memoire de these a ete consacree aux phenomenes d'activation et de desactivation des catalyseurs heterogenes de quatrieme generation. La formation d'un complexe allylique permet d'expliquer les differents phenomenes de blocage et de deblocage du site actif
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Lutz, Marietjie. « Metallocene and Ziegler-Natta catalyzed polypropylene utilizing 1-heptene ». Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52334.
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Thesis (MSc)--Stellenbosch University, 2001.ENGLISH ABSTRACT: This study concerns the copolymerization of propylene with l-heptene. The percentage of l-heptene used as co-monomer in the polymerization reactions was varied from 5% to 20% in order to compare a variety of polymers with different percentages of comonomer incorporated. A variety of different catalysts were used for these polymerizations. Two metallocene catalysts were used: (A) the isospecific catalyst, rae- [ethylene bis(l-indenyl)]zirconium dichloride (rac-Et(Ind)2ZrCh2) and (B) the silylene-bridged catalyst, rac-Me2Si(2-MeBenz[ e]Ind)zZrCh2. Methylaluminoxane (MAO) was used as cocatalyst for these two metallocene catalysts. Another series of polymerization reactions was done using a Ziegler-Natta catalyst, namely TiCb/AlEt3/Si02. Characterization of the copolymers included usmg high temperature gel permeation chromatography (HTGPC) for molecular mass and molecular mass distributions, differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) to investigate the thermal and mechanical properties of the copolymers, nuclear magnetic resonance spectroscopy (NMR) for information concerning the microstructures of the copolymers and crystallization analysis fractionation (CRYSTAF) to investigate the short chain branching of the copolymers. Comparative studies were done on the different catalysts and the polymer properties. The synthesized polymers were also compared with copolymers of propylene with l-hexene and l-octene.
AFRIKAANSE OPSOMMING: Hierdie studie behels die kopolimerisasie van propileen met I-hepteen. Die persentasie van I-hepteen wat as komonomeer in die polimerisasie-reaksies gebruik is, is van 5% tot 20% gevarieer. 'n Verskeidenheid van verskillende kataliste is gebruik vir hierdie polimerisasies. Twee metalloseenkataliste is gebruik: (A) die isospesifieke katalis, rae- [etileen bis(l-indeniel)]zirconium dichloried (rac-Et(lnd)2ZrCh2) en (B) die silileengebrugde katalis, rac-Me2Si(2-MeBenz[e]Ind)2ZrCh2. Metielaluminoksaan (MAO) is as ko-katalis gebruik saam met bogenoemde twee metalloseenkataliste. 'n Ander reeks polimerisasie reaksies is gedoen waarin 'n Ziegler-Natta katalis gebruik is as aktiverende katalis, naamlik TiCi)/ AlEt3/Si02. Die karakterisering van die kopolimere sluit in: hoë temperatuur gel deurlatings chromatrografie (HTGPC) vir molekulêre massa en molekulêre massa verspreidings, differensiële skandering kalorimetrie (DSC) en dinamiese meganiese analisering (DMA) om sodoende die termiese en meganiese eienskappe van die polimere te ondersoek, kern magnetiese resonans spektroskopie (KMR) vir inligting in verband met die mikrostrukture van die kopolimere en kristallisasie analise fraksioneringstegniek (CRYSTAF) om die kort-kettingvertakkings van die kopolimere te ondersoek. Vergelykende studies IS op die verskillende katalisatore en die polimeereienskappe gedoen. Die gesintetiseerde polimere is ook met kopolimere van propileen met I-hekseen en l-okteen vergelyk.
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Wolf, Carlos Rodolfo. « Preparação, caracterização e aplicação de catalisadores Ziegler-Natta na produção de polietileno de alta densidade ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2004. http://hdl.handle.net/10183/117393.
Texte intégralRésumé :
Neste trabalho foram sintetizados catalisadores Ziegler-Natta heterogêneos obtidos a partir de TiCl4 e etilato de magnésio com geração de MgCl2 in situ. Foi verificado que o tempo e a temperatura de têmpera da preparação do catalisador influenciam significativamente a atividade catalítica destes. O catalisador não submetido ao processo de têmpera (ZNST), e o catalisador temperado em condições mais rigorosas (ZNT), apresentaram, respectivamente, a maior e a menor atividade catalítica entre vários catalisadores submetidos a diferentes condições de têmpera. Os catalisadores ZNST e ZNT tratam-se de sólidos amorfos, com área superficial e dimensão de partículas semelhantes. Pela análise da composição química dos catalisadores, por diferentes técnicas analíticas, verificouse que o tratamento térmico do catalisador favorece a fixação de TiCl4 e de compostos de Ti oxigenados, diferentes daqueles depositados na reação do MgCl2 com TiCl4. Nesta Tese foi proposta uma estrutura para os sítios ativos formados à base de compostos de Ti oxigenados ou titanoxanos. Estes resultados permitiram a proposição do modelo físico-químico, denominado núcleo-superfície, segundo o qual o catalisador ZNT é constituído de partículas primárias contendo no núcleo predominantemente sítios de Ti do tipo clorotitanatos, entre outros, e na superfície majoritariamente sítios titanoxano (-Ti-O-Ti-). O catalisador ZNST tem majoritariamente sítios de Ti do tipo clorotitanato. O modelo foi válido para explicar o comportamento dos catalisadores na polimerização de eteno, em processo em suspensão, na obtenção do polietileno de alta densidade (PEAD) e também para explicar as propriedades diferenciadas dos polímeros obtidos. O sistema catalítico ZNST-TEA apresentou maior atividade catalítica e produziu o PEAD de menor massa molar e menor polidispersão. Com o sistema catalítico ZNT-IPRA se verificou atividade catalítica intermediária e PEAD com maior massa molar e maior polidispersão.In this work, Ziegler-Natta heterogeneous supported catalysts were synthesized from TiCl4 and magnesium ethylate with MgCl2 in situ generation. It was observed that both catalyst tempering time and temperature influenced significantly the catalytic activity. The non tempered catalyst (ZNST) and the tempered catalyst (ZNT) presented the highest and the lowest catalyst activity, respectively, among other ones prepared in different tempering conditions. The catalysts ZNST and ZNT are amorphous solids and both have approximately the same surface area and particle size. By the catalyst chemical compositions, determined through different techniques, it was possible to conclude that thermal treatment (tempering) increases the Ti content and new oxygenated Ti sites in the catalyst. In this work was proposed a structure to the new site titanoxane different of that one obtained in the MgCl2 chloration of with TiCl4. These results allow proposing a core-shell model. The core of ZNT catalyst particle has mainly Ti site as chloridetitanate, and others, and the shell has primary particles that have mainly titanoxane sites. The ZNST catalyst has mainly Ti sites as chloridetitanate. The model was valid to explain HDPE properties produced by slurry process. The ZNST-TEA catalytic system showed the highest catalytic activity and the HDPE obtained with this system had the lower molecular weight and the lower polidispersity. The ZNT-IPRA catalytic system showed an intermediate activity and the HDPE obtained had the highest molecular weight and broader polidispersity.
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Warren, Timothy Harold. « Organometallic Group 4 bis(borylamide) complexes as templates for Ziegler-Natta catalysis ». Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/88445.
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Paghaleh, Ali Sharif. « Studies in olefin gas phase polymerization using supported Ziegler-Natta catalysts ». Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.498843.
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Keller, Kayla. « Electronic structure and mechanistic studies of non-traditional Ziegler-Natta catalysts ». Thesis, University of Sussex, 2012. http://sro.sussex.ac.uk/id/eprint/39437/.
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This thesis focuses on the structure and reactivity of a variety of inorganic systems through the exploration of their electronic structure by employing density functional theoretical methods. Chapter 1, the introduction, outlines the theoretical approaches and includes a historical overview of the development of quantum theory. The theoretical methods and their applications are then described and discussed. The first chapter concludes with an overview of the work undertaken. Chapter 2 presents a historical background of the experimental and theoretical work done on traditional Group IV Ziegler-Natta catalysis inculding the generally accepted mechanisms believed to be employed when these systems are used to polymerise olifins. Furthermore, a description of the experimental results obtained when a non-traditional Ziegler-Natta catalyst was subjected to proplyene are given as a rationale for the calculations presented in Chapter 3. Chapter 3 presents a theoretical exploration of a novel class of olefin polymerization catalysts based on the tris(amido)titanium(IV) platform. Here, DFT has been used to probe the electronic structure of these compounds in order to provide a rationale for the catalytic activity that is associated with them as well as a possible new mechanism for this type of non-traditional catalyst. Furthermore, Chapter 4 takes a closer look at a large number of potential intermediates that are available for the polymerization reaction discussed in Chapter 3. In Chapter 5, a series of simple transition metal complexes are calculated and analysed to further understand key aspects of the system. The complexes represent a basic model of the novel catalysts found in Chapter 3 and contain the essential feature of π-acid-base chemistry within the coordination sphere.
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Lorono, Gonzalez Daniel Jose. « An investigation of zwitterionic magnesium complexes as Ziegler-Natta polymerisation catalysts ». Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/12464.
Texte intégralRésumé :
This thesis is concerned with the synthesis and chemistry of series of zwitterionic magnesium complexes, with the aim of providing the first evidence of zwitterionic potential magnesium polymerisation catalysts. The positive charge on the magnesium centre can be stabilised by preparing zwitterionic species incorporating existing and specially developed chelating nitrogen donor ligands. Chapter One serves as general introduction about ethylene polymerisation throughout the periodic table, and the polymerisation activity of magnesium complexes supported by bidentate nitrogen donor ligands. Chapter Two describes the synthesis of a series of magnesium complexes using [K(H2B (pz)}2] ligand. Predominantly [{H2B(py)}2Mg(THF)n] (n: 1 or 2) bischelate complexes are obtained in order to satisfy the electronic requirement of magnesium. The charge transfer from the ligand has the effect of neutralising the formal Mg2+ charges, and this does not produce zwitterionic complexes. Schlenk equilibrium suggests a solvation and association, by which MgCl2 is formed, and associations by u-bridging halide predominate. Chapter Three describes the synthesis of three different borate-centred ligands suggested for zwitterionic magnesium complexes. Chapter Four explores the chemistry of boron supported by the B-diketiminate ligand. Complexation of B-diketiminate ligand with boron results in the formation of several reaction products, via radical processes and provides the first evidence of borane carbine analogue, [HC(MeCNAr’)2B] (Ar’: 2,6-diisopropylphenyl). Chapter Five describes the synthesis of a series of magnesium complexes using [R2AFA(H)] (R:Cy, AFA; 6-aminofulvene-2-aldimine) ligands. Co-ordination of the Cyclopentadienyl (n5-Cp) portion of the ligand results in complexes of zwitterionic character in which a positive charge residues on the magnesium. Schlenk equilibrium suggests a salvation and association, by which MgCl2 is formed to provide complexes [(R2AFA)Mg(Cl)Et2O] and [[(R2AFA)2Mg]. Ethylene polymerisation studies of [(R2AFA)MgME] were implemented and revealed that the compound is inactive under both mild and forcing conditions. Chapter Six explores the technique of high-resolution X-ray diffraction in the complex of [Mg{(pz)2BH}2].
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Nacerodien, Mogamat Thaabit. « Investigation of polymer grade blending in Ziegler-Natta Catalysed ethylene polymerisation systems ». Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/9122.
Texte intégralRésumé :
Includes bibliographical references.Polyethylene is one of the most widely used polymers to date and it is an important commodity in a variety of fields. Most existing polyethylene plants 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 grade transition periods. Numerous studies have been conducted to address the issue of off-spec polymer formation. These studies involve applying optimal control theory to minimise the grade transition time or to minimise the amount of off-spec polymer generated during the transient period. This field of study is known as grade transition optimisation. The current study aims to provide an alternative approach to addressing the problem of offspec accumulation. It is proposed that stored off-spec polymer is blended with virgin polymer to provide a saleable and desirable product. The approach might be different, but the same techniques used in grade transition optimisation are applied. Polyethylene produced using Ziegler-Natta catalysts have relatively linear chains, thus a chain length distribution coefficient is sufficient to characterise the polymer product. The number average chain length and polydispersity index are adequate representatives of this distribution for reporting the properties of a polyethylene grade. For the purpose of applying optimal control theory, a polyethylene production process model was developed to calculate these average properties using a kinetic scheme based on fundamental principles. This process model is able to predict the polymer properties under both steady-state and unsteady-state behaviour. A key feature of the model is its ability to solve the system with low computational expense due to the use of the segregation approach to link particle properties to the overall bulk phase. This is especially useful since optimisation algorithms used in optimal control theory are iterative by nature. The Differential Evolution Algorithm (DEA) was used to minimise the objective functions that were developed for the optimisation schemes due to its ability to evaluate objective functions in parallel. A model of the blending aspect of the process was developed where it was derived that the polymer moments are additive on a mass basis. Pure grades were blended in a laboratory in various mass ratios and analysed using GPC to determine their molecular weight distribution curves. It was found that the model-predicted curves and the experimentally-determined curves were an excellent match, thus validating the model. In the current study, three procedures for blending off-spec material under standard industry conditions are proposed. The first method involves the introduction of off-spec polymer on a continuous basis to the virgin polymer stream during steady-state operation.
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Shafagh, Dehghani Seyedeh. « Study of ethylene/propylene polymerization, using a 4th generation Ziegler-Natta catalyst : Effect of external donor and feed ratio on polymerization ». Thesis, KTH, Skolan för kemivetenskap (CHE), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-147523.
Texte intégralRésumé :
A fourth generation multiple site Ziegler-Natta catalyst was used to synthesize ethylene and propylene homo-and copolymers in the presence of hydrogen. This type of catalysts produce polymers with broader molecular weight distribution (MWD), chemical composition distribution (CCD) and stereoregularity than other coordination polymerization catalysts since it has more than one active site. The ratio of propylene/ethylene was varied to study its effect on polymer microstructure. In addition, by having two different electron donors, namely diisopropyldimethoxysilane (P) and dicyclopentyldimethoxysilane (D), the molecular weight distribution (MWD) and stereospecificity of the synthesized polymers were examined. The polymer samples were characterized using 13C-NMR and high-temperature gel permeation chromatography (GPC). Using the 13C-NMR data, the triad distribution for the copolymers and also the isotactic triad distribution for homo-polymers were calculated. The effects of electron donors on different feed ratios of ethylene and propylene in the synthesis were investigated. Co-polymer produced with D-donors showed higher isospecificity and also higher content of ethylene in the final polymer. In contrast, polymers produced using with P-donor showed lower polydispersity indices (PDI), and had higher contents of propylene in final polymer. In addition, the “Deconvolution method” was applied to GPC data in order to determine the number of sites on the Ziegler-Natta catalyst; which showed that 4 active site types were adequate to explain the molecular weight distributions.
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Silverman, Joel Samuel. « Adventures in group 13 chemistry / ». Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Hair, Gregory Scott. « Synthesis, structure and reactivity of group 13 Lewis acids and group 4 metallocene zwitterions / ». Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Corden, Jonathan P. « The study and synthesis of Group 4 transition metal complexes in Ziegler-Natta catalysis ». Thesis, University of Warwick, 1997. http://wrap.warwick.ac.uk/2471/.
Texte intégralRésumé :
In this thesis a study of Group 4 transition metal complexes and their possible use as Ziegler-Natta catalysts for alkene polymerisation is described. Several tetradentate Schiff base ligands have been synthesised and characterised, including some previously unreported examples. The products obtained from the reactions of Group 4 transition metal halides with the disodium salts of these ligands have been isolated and identified. The stereochemistry of these complexes is important for their use as Ziegler-Natta catalysts, and several complexes have been characterised by X-ray crystallography. [Ti(DMSALEN)Cl2], [Ti(PhSALEN)Cl2], [Ti(SLPNDM)Cl2] and [Zr(SLPNDM)Cl2(THF)] have a trans- geometry at the metal, and the complex [Ti(EtCycH)Cl2] has a cis- geometry. The remaining complexes have been studied by molecular modelling to establish a likely stereochemistry. The reactions of these dichloro complexes with trimethyl aluminium have been studied to gain insight into the chemistry involved in the polymerisation reactions. These reactions proceed with retention of the two chlorine atoms yielding complexes of the type [M(L)Cl2(AlMe3)2] (M = Ti, Zr; L =Schiff base). Side reactions also occur and the by-products [AlMe(EtSALEN)Al(Me)2][AlMeCl3] and [(AlMe2)2(AlMe3)2(EtSALEN)] have been isolated, and characterised by X-ray crystallography. Work was also carried out on the synthesis of complexes of the type (MCl2L) (M = Ti, Zr; L = tetra-azamacrocycle) by the reactions of MCl4 with the dilithium salt of the ligand. These complexes have been fully characterised and the molecular structure of the complex [Zr(omtaa)Cl2] determined by X-ray crystallography. Finally all these complexes have been tested as Ziegler-Natta catalysts for ethene polymerisation. A few selected complexes were also tested for their use in styrene polymerisation and found to be inactive.
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Reid, Steven Marshall 1971. « Chelating polyamido complexes or rhenium, molybdenum, and hafnium : organometallic synthesis to Ziegler-Natta catalysis ». Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/47562.
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Liang, Lan-Chang 1967. « Early transition metal complexes containing tridentate amido ligands : a systematic approach to Ziegler-Natta catalysis ». Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85341.
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Hoza, Adam. « Effect of Ethylene and Propylene on Performance of Ziegler - Natta Catalyst in Stopped - Flow Polymerization ». Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-320775.
Texte intégralRésumé :
Výzkum v této práci byl zaměřen na přípravu a charakterizaci blokových kopolymerů typu polypropylen-blok-poly(propylenu-co-ethylenu) (dále jen PP-blok-EPR). Tyto materiály jsou považovány za účinné kompatibilizátory mezi semi-krystalickou polypropylenovou (PP) matricí a amorfními doménami statistického kopolymeru propylenu a etylenu (EPR) v rázuvzdorném sekvenčním kopolymeru (ICP) a proto byl výzkum zaměřen na zkoumání vlivu přídavku blokového kopolymeru PP-blok-EPR na vlastnosti komerčního ICP. Blokové kopolymery byly připraveny za použití techniky „stopped-flow“. Pro tento účel byla zkonstruována vysokotlaká polymerační „stopped-flow“ aparatura, která umožňuje syntézu kopolymerů PP-blok-EPR za podmínek blízkých podmínkám v průmyslových reaktorech pro výrobu komerčních ICP materiálů. Aparatura umožňuje vyrábět PP-blok-EPR polymer v množství dostačující na jeho charakterizaci a následnou přípravu směsí s komerčním ICP. Velmi krátké polymerační časy (obvykle kolem 0.2 s) kterých bylo dosaženo v kapilárním reaktoru aparatury „stopped-flow“ zajišťuje, že aktivní centra Ziglorova-Nattova katalyzátoru produkují polymer řetězce skládající se z bloku semikrystalického polypropylenu a bloku amorfního EPR kopolymeru. Takovéto molekuly jsou v literatuře popsány jako „skutečné blokové kopolymery PP-blok-EPR“. Kopolymery syntetizované v aparatuře „stopped-flow“ byly frakcionovány preparativní TREF (Temperature Rising Elution Fractionation) metodou a získané frakce byly následně analyzovány pomocí DSC, 13C-NMR a GPC/SEC. Tyto analýzy odhalily přítomnost amorfního EPR ve vysoce krystalické frakci (100-140 °C). Toto zjištění potvrdilo, že významná část polymerních řetězců, připravených v aparatuře „stopped-flow“ jsou blokové kopolymery skládající se z bloku semikrystalického PP homopolymeru a bloku amorfního EPR kopolymeru v jednom polymerním řetězci. Kopolymery získané metodou „stopped-flow" byly v tavenině smíchány s komerčním rázuvdorným kopolymerem ICP. U takto připravených směsí byly vyhodnoceny mechanické vlastnosti, DTMA a reologické vlastnosti a výsledky byly srovnány s vlastmi původního komerčního ICP kopolymeru. Dále byly studovány rozdíly v morfologii a umístění EPR domén v matrici PP prostřednictvím SEM. Zřetelný vliv kopolymeru PP-blok-EPR na vlastnosti ICP byl pozorován zejména v morfologických změnách EPR domén dispergovaných v PP matrici. Tyto změny mají pozitivní vliv na rovnováhu mezi modulem v ohybu a rázovou pevností ICP materiálu. Vliv kopolymeru PP-blok-EPR na reologické vlastnosti ICP byl nevýznamný. Podobně také v případě DTMA nebyl pozorován významný vliv kopolymeru PP-blok-EPR na vlastnosti ICP.
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Ma, Yinlin. « A mechanistic and synthetic study on Ziegler-Natta polymerization catalysts based on vanadium complexes ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ38773.pdf.
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Keaton, Richard J. « Amidinate based catalysts for the stereospecific and living Ziegler-Natta polymerization of [alpha]-olefins ». College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/312.
Texte intégralRésumé :
Thesis (Ph. D.)--University of Maryland, College Park, 2003.Thesis research directed by: Chemistry. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Dick, Caroline. « An investigation of organomagnesium bi/tridentate nitrogen ligand complexes as Ziegler-Natta polymerisation catalysts ». Thesis, University of Edinburgh, 2002. http://hdl.handle.net/1842/13646.
Texte intégralRésumé :
The main objective of this research was to produce magnesium alkyl complexes which are active catalysts or procatalysts in the polymerisation of ethene. The nitrogen based ligands in the magnesium complexes were chosen because of the reported activity of similar transition metal diimine and aluminium alkyl amidinate catalysts. Three classes of compounds were investigated: 1) magnesium di-/tri-amine dialkyl complexes, 2) magnesium alkyl α-diimine complexes, and 3) magnesium alkyl bis(iminophosphorano)methanide complexes. Ethene polymerisation studies of these products were implemented and revealed that these compounds are inactive under both mild and forcing conditions.
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Barthel, Valérie. « Recherche rationnelle de nouvelles bases de Lewis externes en polymérisation du propylène et de l'éthylène par catalyse Ziegler-Natta ». Nancy 1, 1995. http://www.theses.fr/1995NAN10095.
Texte intégralRésumé :
Depuis quelques années, Elf Atochem essaie d'acquérir une connaissance plus approfondie du site actif de la catalyse Ziegler-Natta, par l'élaboration d'un modèle moléculaire permettant de comprendre l'influence de la structure de la base de Lewis dite externe (espèces devenues indispensables si l'on veut induire une forte isospécificité à la croissance de la chaîne de polymère) sur le contrôle de l'isotacticité. L’objectif de la première partie de ce mémoire a été de développer la synthèse de différentes bases de Lewis, dont les caractéristiques structurales correspondent aux impératifs établis à partir de la modélisation, puis tester en polymérisation l'influence de leur structure moléculaire sur la stéréorégulation de la polymérisation du propylène. L’élaboration et l'étude de nouvelles bases de Lewis externes en polymérisations de l'éthylène font l'objet de la seconde partie de ce mémoire. L’étude de bases de Lewis externes phosphorylées est réalisée pour la première fois ici. Une vaste gamme de composés phosphorés de structures très variées ont été synthétisés et engagés en polymérisation de l'éthylène. Cette deuxième partie se termine par un chapitre plus court relatif à des essais concernant l'élaboration de composés pouvant à la fois jouer le rôle de bases de Lewis externes et d'agents de contrôle de l'exothermicité en polymérisation de l'éthylène
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Silveira, Leandro dos Santos. « Efeito das variáveis na preparação de adutos de cloreto de magnésio usados como suporte em catalisadores ziegler-natta de morfologia controlada ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2003. http://hdl.handle.net/10183/163885.
Texte intégralRésumé :
Catalisadores Ziegler-Natta (Z-N) de 4ª geração são preparados com suporte de dicloreto de magnésio com morfologia controlada, obtidos a partir de adutos etanólicos de dicloreto de magnésio (MgCl2.nEtOH). O objetivo deste trabalho foi otimizar o balanço entre as variáveis independentes concentração de reagentes, velocidade de agitação da emulsão e pressão de transferência, na preparação do aduto com controle morfológico. Os adutos etanólicos com controle da morfologia esférica foram preparados pela transferência controlada do aduto fundido a 125 ºC e precipitação por resfriamento brusco (quenching) em não-solvente a – 50 ºC, utilizando o método Controlled Turbulence Emulsion Method (CTEM). A ativação do MgCl2.nEtOH foi feita pela rota química para remoção do etanol e consequente aumento da área superficial do suporte. Os adutos foram preparados com razão molar EtOH/MgCl2 de 3,5 ou 63% (p/p) de etanol. Os experimentos foram realizados segundo planejamento fatorial 23 a dois níveis e ponto central replicado. As variáveis dependentes foram o diâmetro médio e distribuição de tamanho das partículas do suporte, densidade aparente compactada, morfologia e teor de álcool incorporado no aduto. Os catalisadores Z-N’s foram obtidos a partir dos suportes tratados com TiCl4 e um doador de elétrons interno, e testados em polimerização padrão de propileno. Foi observado que o controle do tamanho (diâmetro médio) da partícula do suporte é altamente dependente da velocidade de transferência, controlada pela pressão no reator de fusão. A concentração do reagente ([MgCl2]) teve efeito significativo nas quatro variáveis dependentes. A velocidade de agitação no reator de fusão ou da emulsão do aduto fundido teve efeito significativo somente na morfologia do suporte, sendo este efeito menor que o observado para a pressão de transferência. A velocidade de agitação não teve significância no processo de transferência CTEM, sendo este mais suscetível a variação da pressão no reator.4th Generation Ziegler-Natta catalysts (Z-N catalysts) are prepared with magnesium dichloride support with controlled morphology, obtained from ethanolic adducts of magnesium dichloride (MgCl2.nEtOH). The objective of this work was to optimize the balance between the independent variables reagent concentration, emulsion agitation speed and transfer pressure, in the preparation of the adduct with morphological control. The ethanolic adducts with spherical morphology control were prepared by controlled transfer of the molten adduct at 125 °C and quenching in nonsolvent at - 50 °C using the Controlled Turbulence Emulsion Method (CTEM). The activation of MgCl2.nEtOH was done by chemical route to remove the ethanol and consequently increase the surface area of the support. The adducts were prepared with EtOH/MgCl2 molar ratio of 3.5 or 63% (w/w) ethanol. The experiments were performed according to factorial design 23 at two levels and replicated central point. The dependent variables were the mean diameter and particle size distribution of the carrier, compacted bulk density, morphology and alcohol content incorporated in the adduct. The Z-N’s catalysts were obtained from TiCl4-treated media and an internal electron donor, and tested in standard polypropylene polymerization. It has been observed that size control (median diameter) of the carrier particle is highly dependent on the transfer rate, controlled by the pressure in the fusion reactor. The concentration of the reagent ( [MgCl2] ) had a significant effect on the four dependent variables. The stirring rate in the melt reactor or the cast adduct emulsion had significant effect only on the morphology of the support, this effect being smaller than that observed for the transfer pressure. The stirring speed was not significant in the CTEM transfer process, which is more susceptible to pressure variation in the reactor.
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Duprez, Virginie. « Synthèse des hydroxyalkyl pyrazoles, leurs complexes de titane et application en polymérisation ». Aix-Marseille 3, 2002. http://www.theses.fr/2002AIX30007.
Texte intégralRésumé :
Dans ce travail visant à développer de nouveaux catalyseurs qualifiés de post métallocènes, nous nous sommes fixés trois objectifs. Le premier concerne la préparation de plusieurs familles de substrats hydroxyalkyl pyrazoliques simples d'accès à partir du noyau pyrazolique dont un atome d'azote est substitué par une chaîne hydroxyalkyle. Ces ligands hétéroatomiques ont été synthétisés via des réactions d'alkylation, d'ouverture d'époxydes et de condensation directe de composés b-dicarbonylés avec des dérivés de l'hydrazine. La seconde partie a porté sur l'étude des modes de coordination de ces différents ligands potentiellement bidentés au titane, la synthèse des complexes de Ti(IV) correspondant et leur caractérisation. Enfin, l'application de ces complexes de Ti(IV) en tant que catalyseur de polymérisation vis à vis d'alcènes a révélé une activité intéressante. Plusieurs de ces complexes catalysent notamment la formation d'un polyéthylène de masse moléculaire élevéeDuring this project consisting in the development of new post metallocene catalytic systems, we fixed us the following three objectives : the syntheses of new ligands, preparation of titanium complexes and polymerisation reactions. The first part describes the syntheses of several hydroxyalkyl pyrazoles families, easily access with the pyrazole nucleus in which one nitrogen is substituted with an hydroxy alkyl side chain. These heteroatomics ligands are synthesised via alkylation reaction, epoxide ring opening or direct condensation of b diketones with hydrazine derivatives. The second part deals with the study of coordination modes of the different ligands with Ti, the syntheses of Ti(IV) complexes and their characterisation. Finally, the application of these Ti complexes as polymerisation catalysts with alkenes revealed an interesting activity. Several of the single site catalysts are able to convert ethylene in high molecular weight polyethylene
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Batt-Coutrot, Delphine. « Recherche de nouveaux catalyseurs isospécifiques destinés à la polymérisation du propylène : catalyse Ziegler-Natta et métallocène ». Nancy 1, 2000. http://www.theses.fr/2000NAN10070.
Texte intégralRésumé :
Depuis les années 50, la polymérisation par catalyse Ziegler-Natta a suscité de nombreuses études. Ainsi, Atofina essaie d'acquérir une connaissance plus approfondie du site catalytique par l'élaboration d'un modèle moléculaire afin de comprendre l'influence de la base de Lewis "externe"sur le contrôle de l'isotacticité. La première partie décrit la synthèse de différentes bases de Lewis, dont les caractéristiques structurales correspondent aux impératifs établis par la modélisation. De nouveaux donneurs d'électrons silylés ou en série [gamma]-diéther très difficiles à préparer ont été synthétisés puis testés en polymérisation du propylène au Groupement de Recherche de Lacq. Deux composés inédits ont montré des performances tout à fait remarquables puisqu'ils permettent d'obtenir des résultats supérieurs à ceux des meilleures références actuelles. La deuxième partie concerne l'étude au laboratoire du comportement des réactifs dans des conditions expérimentales aussi proches que possible de celles du réacteur en continu à l'échelle industrielle. Une étude de l'évolution des systèmes catalytiques dans des conditions voisines de celles adoptées en polymérisation est présentée afin de comprendre 'le comportement variable des meilleurs catalyseurs en fonction de leur mode de préparation et d'utilisation. Une troisième partie est consacrée à la synthèse de métallocènes. Atofina, un des plus grands producteurs européens de polyaléfines, s'intéresse de très près au développement spectaculaire de ces composés. La synthèse de zirconocènes haute performance a été réalisée, afin de vérifier ou d'améliorer la faisabilité des meilleurs catalyseurs décrits. Ces nouveaux systèmes ont été testés en polymérisation du propylène. Cette étude a permis de réaliser deux objectifs importants : cerner les possibilités de ces systèmes et apprécier les difficultés de mise en oeuvre des réactions de polymérisation.
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Duc, Sandrine. « Synthèse de (co)polymères d'hex-1-yne et de phénylacétylène par les catalyseurs de Ziegler-Natta et de métathèse : caractérisation de la microstructure des chaines par couplage pyrolyse - chromatographie en phase gazeuse/spectrométrie de masse ». Vandoeuvre-les-Nancy, INPL, 1997. http://www.theses.fr/1997INPL044N.
Texte intégralRésumé :
Cette étude est consacrée à la (co)polymérisation d'un couple de monomères acétyléniques monosubstitués, phénylacétylène (PA)/hex-1-yne (HX), en présence de catalyseurs de coordination. L’objectif principal est de décrire la microstructure, en termes de distribution des séquences, de ces copolyalcynes par la technique de pyrolyse couplée à la chromatographie en phase gazeuse et à la spectrométrie de masse (Py-GC-MS). La première partie traite de l'homopolymérisation et de la copolymérisation du PA et de HX en présence des catalyseurs de Ziegler-Natta, Ti(O-n-Bu) ₄ -AlEt₃ et Fe(acac) ₃-AlEt₃, et de métathèse, WCl₆-Ph₄Sn en solution dans le toluène ou le 1,4-dioxane. La stéréochimie de la réaction, en terme d'isomérie géométrique cis/trans, est très influencée par la nature de l'amorceur. Les rapports de réactivité, mesures comparativement par le procède de Kelen-Tüdös et par régression non linéaire, indiquent que la copolymérisation du couple PA/HX est déterminée par le seul effet terminal pour les différents systèmes catalytiques utilises. La seconde partie est consacrée à l'étude de la microstructure des (co)polyalcynes par Py-GC-MS. La thermolyse de ces produits libère très majoritairement des trimères cycliques sans restitution de monomère. La nature et l'abondance relative de ces cyclotrimeres sont caractéristiques de la composition chimique et de la microstructure du copolymère décomposé. Cette méthode a permis, d'une part, d'identifier et d'estimer les inversions d'enchainement dans les homopolymères et, d'autre part, d'analyser la répartition des triades et le run number qui caractérisent les copolymères.
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Enright, Dave S. « The search for new catalysts for Ziegler-Natta olefin polymerization : Exploratory studies in unusual direction ». Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/26331.
Texte intégralRésumé :
The preparation of two tetravalent d2 chromium alkyls is revisited. Their ability to work both as starting materials for further functionalization and as Ziegler-Natta catalysts is investigated. The clarification of the reaction pathway through which a trivalent chromium salt may form a homoleptic tetravalent derivative is also considered. Finally, the elucidation of the nature of the Cr-Cr interaction in a unique [R2Cr] 4 tetranuclear cluster and evaluation of its stability is undertaken.
This is followed by a reassessment of the stability of tetravalent vanadium alkyls. Wilkinson first reported, in the seventies, the preparation of homoleptic R4V species [R = C6H5, CH2Si(CH 3)3]. The full characterisation of a homoleptic R4V, by crystal structure, and testing the catalytic activity is reported.
The alpha,alpha-diiminopyridine ligand {alpha,alpha' -[2,6-(i-Pr)2PhN=C(Me)]2(C 5H3N)} has recently attracted considerable attention because of its ability to form highly active polymerization catalysts. Recent work from this research group and others has shown that this alpha,alpha '-diiminopyridine ligand can be involved in the organometallic transformations of the metal center. The ability of the ligand to accept or to donate negative charge to the metal is central to the fine tuning of the redox potential of the metal, and of its Lewis acidity that in turn determines the catalytic behaviour.
A clarification for the ability of this remarkable ligand system to accept negative charge is offered. Reductions of {alpha,alpha'-[2,6-(i-Pr) 2PhN=C(Me)]2(C5H3N)} with strong reductants such as Li and Li(naftalenide) and in the absence of transition metals were carried out to yield rare case trilithium organyls.
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Silva, Gustavo Monteiro da. « Copolimerização de 1,3-butadieno e alfa-olefinas com catalisadores à base de versatato de neodímio ». Universidade do Estado do Rio de Janeiro, 2010. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=2765.
Texte intégralRésumé :
Nesta Dissertação, foram realizadas reações de copolimerização de 1,3-butadieno com diferentes alfa-olefinas (1-hexeno, 1-octeno e 1-dodeceno) utilizando-se um sistema catalítico do tipo Ziegler-Natta ternário constituído por versatato de neodímio, hidreto de diisobutilalumínio e cloreto de t-butila. O sistema catalítico também foi avaliado em reações de homopolimerização com cada alfa-olefina. As condições reacionais, tanto da síntese do catalisador como das reações de polimerização, foram mantidas constantes. Foi estudada a influência de diferentes teores de cada alfa-olefina (1, 3, 5, 10, 20 e 30 % em relação ao 1,3-butadieno) sobre a conversão da polimerização, a microestrutura, a massa molar, as propriedades viscosimétricas e a estabilidade térmica dos polímeros obtidos. Foi avaliada, ainda, a influência do tamanho da cadeia da alfa-olefina sobre as características da polimerização. Os polímeros foram caracterizados por espectroscopia na região do infravermelho (FTIR), cromatografia por exclusão de tamanho (SEC), viscosimetria capilar e termogravimetria (TG). A microestrutura dos polímeros, praticamente, não variou com a adição das alfa-olefinas. A massa molar numérica média (Mn) não sofreu alterações significativas, enquanto que a massa molar ponderal média (Mw) apresentou tendência ao aumento, quanto maior foi a incorporação de comonômero. A viscosidade intrínseca não apresentou uma tendência com a adição da alfa-olefina na reação, permanecendo na faixa de 2,015 a 3,557 dL/g. A estabilidade térmica do copolímero mostrou uma tendência a aumentar com a incorporação das alfa-olefinasIn this work, were performed copolymerization reactions of 1,3-butadiene with different alpha-olefins (1-hexene, 1-octene and 1-dodecene), using a ternary catalytic system of Ziegler-Natta, constituted by neodymium versatate, diisobutylaluminum hydride and t-butyl chloride. The catalytic system was also evaluated in homopolymerization reactions with the alpha-olefins. The reaction conditions, both the catalyst synthesis as the polymerization reactions, were kept constant. The influence of different content of each alpha-olefin (1, 3, 5, 10, 20 and 30% compared to 1,3-butadiene) on the polymerization conversion, the microstructure, molar mass, viscometric properties and thermal stability of polymers was studied. The influence of alpha-olefin chain size on polymerization characteristics was also evaluated. The polymers were characterized by infrared spectroscopy (FTIR), size exclusion chromatography (SEC), capillary viscometry and thermogravimetry (TG). The polymer microstructure, practically, did not change with the addition of alpha-olefins. The number average molecular mass (Mn) has not changed; while the weight average molecular mass (Mw) trended to increase. The intrinsic viscosity did not show a trend with the alpha-olefin addition, remaining in the range from 2.015 to 3.557 dL/g. The copolymer thermal stability showed a tendency to increase with the incorporation of alpha-olefins
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Butcher, Mark Leslie. « A study of some novel cationic complexes of the group 4 metals and their applications in Ziegler-Natta catalysis ». Thesis, University of Warwick, 1994. http://wrap.warwick.ac.uk/2542/.
Texte intégralRésumé :
The reactions between antimony(v) chloride and the monocyclopentadienyl metal trichlorides of Group 4 (CpMCl3 for M = Ti, Sr and Hf) in acetonitrile solution have afforded new hexachloroantimonate salts. These cationic metal-containing products have been isolated and characterised using IR, 1H NMR, elemental analysis, and in two cases, X-ray crystallography. The analogous pentamethylcyclopentadienyl (Cp*) systems have also been investigated, with largely similar results. Depending on the stoichiometry employed in the reaction, the relevant mono-, di- and tri-cationic complexes can be formed via halide exchange. For the Cp/Cp*TiCl3 series, a 1:1 or 2:1 ratio of Sb:Ti affords [CpTiCl2(MeCN)3][SbCl6] and [CpTiCl(MeCN)4][SbCl6]2 respectively. A ratio of 1:6 is required to yield pure [CpTi(MeCN)5][SbCl6]3. The 16-electron, pseudo-octahedral geometry of the latter complex was confirmed by X-ray analysis. A similar situation is found in the analogous Zr and Hf cases. However, the formation of the triply-charged complexes is accompanied by an expansion in coordination number about the metal centre; X-ray crystallographic studies revealed the 18-electron [CpZr(MeCN)6][SbCl6]3 to exhibit a pseudo-pentagonal bipyramidal geometry. The reactivity of the CpTi3+ salt towards a variety of both neutral and anionic species has been investigated. In acetonitrile solution, the complex rects with amines to give insoluble mixtures of partially substituted products. Adduct formation with ethers and trimethylphosphine is slow and only occurs when non-coordinating solvents are employed. The complex reacts with inorganic salts to reform neutral CpTiX3 compounds by simple anion exchange. The Ziegler-Natta catalytic activity of the cationic series has been studied. In the presence of methylaluminoxane cocatalysts, the complexes polymerise ethene but their activity is inversely proportional to the charge on the metal.
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Schattenmann, Florian Johannes 1965. « Polyenes by regioselective, living polymerization using molybdenum alkylidene bis(carboxylate) initiators and Ziegler-natta catalysis employing new zirconium diamido complexes ». Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42770.
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McCoy, John Themba. « Development of a computationally efficient model for the control of Ziegler-Natta catalysed industrial production of high density polyethylene ». Doctoral thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20347.
Texte intégralRésumé :
High density polyethylene is commonly produced by the slurry phase co-polymerisation of ethylene and other 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 reactor model may allow for minimising losses during unsteady-state operation. Such a model must be developed from a fundamental understanding of polymerisation reaction kinetics and the interaction of effects at various scales, including those of catalyst sites, catalyst/polymer particles and reactor hydrodynamics. The model must also be computationally efficient enough for application to real-time control. The recently-developed pseudo-sites model was used as a fundamental kinetic explanation of polymer property distributions and catalyst activity profiles, in contrast to empirical multi-site models. Laboratory polymerisation experiments were performed at industrially-relevant conditions. Kinetic parameters were fitted to the data, using a novel proposed regression procedure to extract meaningful kinetic parameters. A dynamic reactor model was developed, based on the Segregation Approach. Whereas the more common Population Balance Model must consider multivariate distributions of population members within a chosen volume and requires partial differential equation solution, the Segregation Approach can generate the moments of a distribution by evaluating the evolution of properties without requiring solution over the whole volume. The Segregation Approach and PBM were rigorously compared in the context of Particle Size Distributions, and the Segregation Approach shown to be an order of magnitude more computationally efficient. Steady-state industrial data was used to reconcile model predictions for laboratory and industrial polymerisation. This was the first application of the pseudo-sites model to laboratory data, and first extension to industrial scale. Unsteady-state data from three industrial grade transitions was used to validate the reactor model, which closely matched industrial reactor performance. The model simulated 30-40 hours of real time in 15-25 seconds of calculation time. The reactor model was used to propose improved grade transition strategies; transition duration and waste production were improved by 20-40%. The reactor model has been shown to accurately reproduce real-world results, and is computationally efficient enough to be applied to model-based control applications.
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Lorenzini, Pascal. « Polymérisation de l'éthylène sous haute pression : développement et validation de modèles de polymérisation radicalaire et de copolymérisation Ziegler-Natta ». Vandoeuvre-les-Nancy, INPL, 1991. http://www.theses.fr/1991INPL032N.
Texte intégralRésumé :
La présente étude consiste à développer et valider des modèles de polymérisation de l'éthylène sous haute pression afin de prédire la qualité du polymère en fonction des conditions opératoires (pression, température, débit et composition de l'alimentation,. . . ) et de fournir aux industriels un outil d'aide à la décision pour la conduite des lignes de fabrication. Notre approche, dite modèle de tendance n'est pas analytique détaillée ni de type boite noire. La structure moléculaire du polymère est représentée par des pseudo-constituants, tels les indices de branchement ou les moments de la distribution des masses moléculaires, dont les débits de production sont calculés sur la base de schémas cinétiques réalistes. La première partie de ce travail concerne la polymérisation radicalaire. A partir d'un modèle préexistant, nous avons mis au point une méthode originale de calcul de la distribution des masses moléculaires et une technique de calage des paramètres cinétiques qui permet d'estimer quantitativement la structure moléculaire. La seconde partie a trait à la copolymérisation de l'éthylène et des alpha-oléfines par catalyse Ziegler-Natta selon le procédé en masse. Le modèle comporte plusieurs types de sites actifs, dont les paramètres cinétiques ont été identifiés grâce à des essais conduits sur une installation pilote industrielle, dans le cas de la copolymérisation éthylène butene-1. Le modèle a pu être validé par des simulations. Sur le plan théorique, il a été montré que notre approche s'appliquait à d'autres alpha-oléfines que le butene-1. La transposition de ces modèles aux réacteurs industriels a été en partie réalisée. Sur le plan informatique, nous disposons de logiciels de simulation utilisables en usine sur micro-ordinateur. Toutefois, les exploitants n'adhèreront pleinement à la modélisation que lorsque les propriétés d'application d'usage courant seront reliées à la structure moléculaire sur une base scientifique solide
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Ferreira, Cíntia Nogueira. « Influência do agente de halogenação e da razão molar Cl:Nd na polimerização e nas características do polibutadieno obtido com catalisador Ziegler-Natta à base de neodímio ». Universidade do Estado do Rio de Janeiro, 2008. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=2616.
Texte intégralRésumé :
Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorNesta Dissertação foi utilizado um sistema catalítico Zieger-Natta à base de neodímio para avaliar a influência do agente de halogenação e da razão molar halogênio:Nd sobre a atividade catalítica, a constante de velocidade de propagação, a conversão da polimerização, a microestrutura, a massa molecular e a polidispersão do polibutadieno 1,4-cis. O sistema utilizado era constituído por versatato de neodímio (NdV), hidreto de diisobutilalumínio (DIBAH) e um agente de halogenação. Os agentes halogenantes estudados foram: cloreto de t-butila (t-BuCl), sesquicloreto de etilalumínio (EASC) e cloreto de dietilalumínio (DEAC), em valores de razão molar Cl:Nd que variaram entre 0,5:1 e 5:1 e o dietil-eterato de trifluoreto de boro (BF3.Et2O), na razão molar F:Nd = 3:1. Os polímeros foram caracterizados por espectroscopia na região do infravermelho para determinação da microestrutura e por cromatografia de exclusão por tamanho para determinação das massas moleculares. O teor de unidades 1,4-cis variou de 90 a 98%, a massa molecular numérica média ( ) permaneceu na faixa entre 0,2 e 2x105, e a massa molecular ponderal média ( ) variou de 1,4 a 4x105
In this Dissertation a catalyst system based on neodymium was employed to evaluate the influence of halogen source and the halogen:Nd molar ratio on the catalyst activity, polymerization constant rate, polymerization conversion, molecular weight characteristics and microstructure of polybutadiene. The catalyst systems were formed by diisobutylaluminium hydride (DIBAH), neodymium versatate (NdV) and a halogen source. The halogenating agents studied were t-butyl chloride (t-BuCl), ethylaluminium sesquichloride (EASC) and diethylaluminium chloride (DEAC) in a nCl:nNd molar ratio in the range from 0,5 to 5, and boron trifluoride diethyl ether (BF3.Et2O). The polymers were characterized by infrared espectroscopy for determining the microstructure and by size exclusion chromatography to obtain the molecular mass characteristics. The cis-1,4 units contents varied from 90 to 98%, the number-average molecular mass ( ) varied from 0,2 to 2x105 and the weight-average molecular mass ( ) varied from 1,4 to 4x105
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Tvrdý, Michal. « Stanovení kinetiky polymerace propenu na Zieglerových-Nattových katalyzátorech metodami násadové polymerace a Stopped-Flow za průmyslových podmínek ». Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2019. http://www.nusl.cz/ntk/nusl-401930.
Texte intégralRésumé :
This thesis is focused on the determination of the propene polymerization kinetics on phthalate and nonphthalate diester Ziegler-Natta MgCl2-supported catalysts under the industrial conditions. The kinetic profiles were determined by various laboratory techniques for propene polymerization. For assessing the profiles were utilized batch gas and liquid polymerization modes in 2-litre and 4-litre reactors. Finally, the results were complemented with the runs performed in a unique Stopped-Flow apparatus, which allows polymerization of liquid propene at very short polymerization times. The kinetics profiles of both catalysts were determined and compared by combination of experimental data of these techniques. The basic properties of the synthesized polymeric powders were measured, such as the melt flow index, bulk density and amount of polypropene fraction soluble in cold xylene.
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Shichen, Yu. « CHAIN ENTANGLEMENTS EFFECTS IN NASCENT ULTRA-HIGH MOLECULAR WEIGHT POLYPROPYLENE SYNTHESIZED BY ZIEGLER – NATTA MULTIPLE-SITES AND METALLOCENE SINGLE-SITE CATALYSTS ». University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1620286973657457.
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Gažo, Peter. « Vliv předpolymerace MgCl2- nosičovéhoTiCl4 katalyzátoru na polymeraci propenu a vlastnosti výsledného polypropenového prášku ». Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2018. http://www.nusl.cz/ntk/nusl-376841.
Texte intégralRésumé :
Cílem této práce bylo prostudovat vliv předpolymerace na vybraný komerční MgCl2–nosičový TiCl4 katalyzátor (tzv. Zieglerův-Nattův). Výsledkem práce bylo nalezení optimálních podmínek, které umožní ideálně využít této techniky k modifikaci struktury a morfologie zvoleného katalyzátoru a dosažení stabilnějšího průběhu polymerace a lepších vlastností produkovaného polypropenu. U předpolymerací byl studován vliv teploty, koncentrace triethylhliníkového kokatalyzátoru a externího donoru, množství polyolefinu syntetizovaného během předpolymerace (tzv. stupeň předpolymerace) na následné chování předpolymerovaného katalyzátoru při plynofázní polymeraci propenu.
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Kolomazník, Vít. « Vliv katalytického systému na strukturu E/P kopolymerů ». Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2019. http://www.nusl.cz/ntk/nusl-401947.
Texte intégralRésumé :
Thesis is focused on structural study of ethylene-propylene copolymers (E/P copolymers) produced by gas phase polymerization. Goal of work was to determine the effect of used catalysts on the distribution of ethylene units in the resulting material. Three E/P copolymers were prepared on commercial Ziegler Natta catalysts with diether or phthalate based internal donors. The copolymers were fractionated according crystallization ability and molar mass. Next, the mass content and the distribution of the ethylene units in the copolymer were determined in each fraction by nuclear magnetic resonance (NMR). Together with other structural analytical methods, phthalate internal donor has been found to produce ethylene blocks under certain conditions, while the diether ID lacks this ability.
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Hoza, Adam. « Vliv přídavku ethenu na aktivitu Z-N katalyzátoru pro nízkotlakou polymeraci propenu ». Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-216658.
Texte intégralRésumé :
The aim of the study will be the determination of the kinetic profiles of the polymerization of propene, ethene and their mixtures with commercial Ziegler-Natta catalyst by application of two different experimental procedures. The prepared polymer material will be utilized for the SEC analysis and subsequent evaluation of the concentration of active sites. The determined molecular mass distribution curves will be further investigated by the application of the procedure, which deconvolute the overall profile on the basic Flory's distribution functions. Then the comprehensive study about character and behavior of various types of active centers in dependence on time and type of monomer will result from this investigation.
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Aouak, Taïeb. « Homopolymérisation et copolymérisation des alcynes monosubstitués amorceées par les complexes de Ziegler-Natta : étude de réactions conduites en présence de catalyseurs solubles formés en associant un carboxylate de fer(III) et un alkylaluminium, caractérisation des polyalcynes ». Vandoeuvre-les-Nancy, INPL, 1994. http://docnum.univ-lorraine.fr/public/INPL_T_1994_AOUAK_T.pdf.
Texte intégralRésumé :
L'étude comparative de l'efficacité d'une série de dérivés organoferriques aliphatiques, alicycliques et aromatiques, combinés à AlEt3, sur la polymérisation du hex-1-yne (HX), a revelé que les composés Fe(CH3CH2CO2)3, Fe(naph)3 et Fe(C6H11CO2)3, sont doués d'une haute activité catalytique (Rdt 100%, Mn=6. 10^4). Les essais conduits en présence du couple Fe(CH3CH2CO2)3AlEt3, montrent que cette combinaison est parfaitement appropriée pour polymériser les alcynes terminaux: 3-méthylpent-1-yne, 4-méthylpent-1-yne et phénylacetylène (PA). Les 3-triméthylsiloxyprop-1-yne (TMSOP) et 1-triméthylsilylpenta-1,4-diyne (TMSPD), polymérisent également sous l'action de ces complexes amorceurs (Rdt 70%, mn = 10^5). L'encombrement stérique du groupe Si(CH3)3 est suffisamment important pour protéger efficacement tout site réactif auquel il est directement lié (-O-, -C=C-) envers les agents organométalliques qui composent le système amorceur. Le processus de croissance, évalue en termes de rendement et de microstructure (cis/trans), des produits formes, est influencé par l'encombrement stérique du substituant avoisinant le carbone sp. La copolymérisation des couples PA/HX, PA/TMSPD, HX/TMSOP et PA/TMSOP montre que les alcynes examinés copolymérisent par voie Ziegler-Natta. Les rapports de réactivité indiquent que le régime d'incorporation des deux partenaires est déterminé par le seul effet terminal. Ces rapports révèlent que les trois premiers couples sont dépourvus de composition azéotrope et ont une certaine tendance à l'alternance des deux résidus alors que le quatrième présente un azéotrope à environ 98% de PA dans la charge et une propension à former des séquences homogènes. L’étude du vieillissement à l'air et à la lumière de ces polymères montre que la vitesse d'altération de leurs caractéristiques physicochimiques est une fonction décroissante de l'effet d'encombrement stérique du substituant lié au squelette macromoléculaire
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Ramachandran, Ramnath. « Quantification of Structural Topology in Branched Polymers ». University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1326828758.
Texte intégral
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Liu, Huaqin. « Etude de l'oligomérisation des alpha-oléfines amorcées par des systèmes bimétalliques à base de dérivés d'un métal de transition (groupe IV B) et de composés organoaluminiques ». Paris 6, 1986. http://www.theses.fr/1986PA066087.
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FREDIANI, MARCO. « Polymerization of olefins by early and late transition metal catalysis ». Doctoral thesis, 2004. http://hdl.handle.net/2158/591897.
Texte intégralRésumé :
La tesi è stata svolta in cotutela con l'Università di Amburgo secondo una convenzione bilaterale tra CRUI (Prof. Dr. L. Modica) e HRK (Prof. Dr. K. Landfried), firmata a Berlino nel Novembre 2000, in cui si raccomandava la supervisione bi-nazionale delle tesi di dottorato. Da questa esperienza è scaturito il riconoscimento del titolo di dottorato anche tedesco.
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Chen, You-Xian. « Specifically designed homogeneous Ziegler-Natta metallocene catalysts : Strategy, synthesis and polymerization catalysis ». 1995. https://scholarworks.umass.edu/dissertations/AAI9524685.
Texte intégralRésumé :
Strategies for designing specified Group IV ansa-metallocene olefin polymerization catalysts have been provided. In efforts to suppress the formation of undesired meso isomers of ansa-bis(indenyl)metallocene complexes, the previously enantiotopic faces of indenyl ligands were converted into diastereotopic faces by placing a chirality on the bridging atom, thus favoring the formation of an optically active, C$\sb2$-symmetric single diastereomer by means of diastereofacial selection. After achieving the correlation between the theoretical and experimental racemic/meso ratios in the synthesis of many known ansa-metallocenes by means of molecular mechanics (MM) calculations, MM studies were performed to predict racemic/meso ratios in the synthesis of specifically designed unknown ansa-metallocenes. A variety of 25 new organic ligands and organometallic complexes have been synthesized in this study. A thermal diastereomerization of indenylsilane ligands has been discovered and studied by the dynamic NMR technique. By carefully tuning the electronics and steric hindrance of ligand frameworks, five series of catalytic systems have been generated; they are a silacyclobutane-bridged bis(indenyl)zirconocene, a tetraphenylgermacyclopentadiene-bridged bis(indenyl)zirconocene derived from a stereoselective synthesis with aid of a MM calculation, a heptane-soluble homogeneous zirconocene catalyst with bis(menthoxy)silylene as the bridge, C$\sb{2\nu}$- and C$\sb2$-symmetric ansa-bis(fluorenyl)zirconocene catalysts, and silylene-bridged fluorenyl-containing ansa-zirconocene complexes with C$\sb1$ and C$\sb{s}$ symmetry. Polymerization catalysis has been carried out, leading to isospecific, syndio-specific or non-stereospecific polymerizations of $\alpha$-olefins with the five types of catalysts synthesized, using different activation methods. Three significant major objectives have been accomplished in the dissertation study: (1) generation of the first heptane-soluble homogeneous Ziegler-Natta catalyst with extremely high activity; (2) stereoselective synthesis of a temperature-invariant propylene polymerization catalyst over a broad polymerization temperature range; (3) the synthesis of a C$\sb{2\nu}$-symmetric catalyst that produces atactic polypropylene with a molecular weight of one-half million and with high activity.
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Mischenko, John. « Preparation and investigation of model surfaces for the study of Ziegler-natta catalysis ». Thesis, 1990. http://hdl.handle.net/1957/37473.
Texte intégralRésumé :
Single crystal surfaces can be used as substitutes or
models for the actual reactive surfaces of heterogeneous
catalysts. The advantage in using such models is that the
reaction of interest can be isolated on the particular
face of the crystal that is thought to be catalytically
active. A variety of ordered chlorine covered Ti surfaces
were prepared which should be useful as model surfaces for
studying Ziegler-Natta reactions. These include a
chlorine covered Ti(100) surface on which a 4x6 LEED
pattern was observed and a chlorine covered Ti(001)
surface, on which a chlorine coincidence lattice was
formed.
The reactivity of clean and partially chlorine
covered Ti(001) and (100) surfaces toward ethylene was
also studied. During the investigation of ethylene uptake
an epitaxial layer of TiC(lll) was produced on the clean
Ti(001) surface. Ethylene uptake curves and carbon
segregation to the chlorine covered crystal face are
reported for various fractional chlorine coverages.
Sulfur segregation from the bulk, to the surface of a
Ti single crystal was studied and ordered LEED patterns
recorded on ,both the Ti(001) and Ti(100) surfaces. The
sulfur covered surfaces were in turn used in additional
experiments designed to investigate the uptake of chlorine
and the thermal desorption of chlorine from a sulfur
covered surface.Graduation date: 1991