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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Determination and evaluation of electrical properties of metal-containing condensation polymers

Unknown Date (has links)
Doped electrically conductive polymers are one of the critical materials that have allowed the current technological revolution. Essentially all of today's applications of doped conductive polymers involve vinyl-related polymers. While the application of conductive polymers is rapidly increasing, there is need for additional materials with different electrical behaviors. The current focus is on studying condensation polymers that contain a metal atom and the possibility of undergoing entire chain delocalization of electrons. The different series of organometallic condensation polymers were synthesized by employing interfacial polycondensation technique and characterization of these products were carried out using standard techniques like light scattering photometer, fourier transform infrared spectroscopy (FTIR), matrix assisted laser desorption ionization time of flight mass spectroscopy (MALDI TOF MS) and nuclear magnetic resonance spectroscopy (NMR). The electrical measurements were carried out employing Genrad 1650-B impedance spectroscopy. Prior studies conducted in this area have led to the pathway of looking at two aspects; first, surveying 60 metal-containing polymers that can undergo entire chain delocalization studying the effect of different substituents on their electrical properties and secondly, doping selected candidates employing iodine. The products derived from 2-nitro-1,4-phenylenediamine and N-methyl-1,4- pheneylenediamines with titanocene dichloride exhibited about 10 3 to 10 5 fold magnitude increases in the electrical conductivity on doping with iodine, moving it near conductive region. This increase is dependent on the concentration of the iodine and is cyclic. The results support the starting premise that selected metal-containing condensation polymers can be doped to increase their electrical conductivity. / Further investigation is warranted to see if metal-containing condensation polymers can be important materials in the electronic industry. This research sets the stage for studying not only metal-containing polymeric materials but also to investigate the ability to increase the conductivity of other condensation polymers such as nylons and polyesters through doping. / by Amitabh J. Battin. / Thesis (Ph.D.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.
12

Aplicação de catalisadores de alta eficiência ma síntese de poliésteres derivados de isosorbídeo / Application of high-efficiency catalysts in synthesis of polyesters derived from isosorbide

Luengo, Fernando Alves Gomes 28 November 2016 (has links)
O isosorbídeo, juntamente com o ácido láctico, é considerado importante monômero para a preparação de materiais poliméricos derivados de fontes renováveis. O presente trabalho descreve a aplicação de catalisadores de alta eficiência na síntese de poliésteres derivados de fontes renováveis. Diésteres alifáticos, isosorbídeo, lactídeo, 2-etilhexanoato de estanho II (SnOct2), triflato de itérbio [Yb(OTf)3] e triflato de ítrio [Y(OTf)3], foram utilizados como reagentes para a produção dos polímeros em estudo. O catalisador de estanho, por ser o mais comum na literatura para esse tipo de sistema, foi utilizado como referência para a aplicação dos catalisadores de alta eficiência derivados de ítrio e itérbio. A estratégia inicial adotada para a obtenção da maior massa molar possível dos polímeros foi a execução de um planejamento fatorial para avaliação de como três variáveis principais, temperatura, tempo reacional e quantidade de catalisador influenciam o processo de polimerização. Uma vez determinada a direção a ser seguida no processo de polimerização, ajustes empíricos baseados em dados e observações experimentais foram feitos com a finalidade de se otimizar as condições reacionais. Os produtos obtidos foram caracterizados por cromatografia por exclusão de tamanho, ressonância magnética nuclear de 1H e 13C, espectroscopia no infravermelho, calorimetria diferencial de varredura, análise termogravimétrica e espectrometria de massas. Catalisadores de alta eficiência foram utilizados na preparação de poliésteres de alta massa molar, sintetizados a partir de lactídeo, diésteres alifáticos e diol secundário estericamente impedido, o isosorbídeo. Polímeros ramificados inéditos foram obtidos e um novo mecanismo reacional proposto, permitindo uma melhor compreensão sobre o sistema de policondensação para derivados de isosorbídeo. / The isosorbide and lactic acid are considered important monomers from renewable sources for the preparation of biodegradable materials. The present study describes the use of high performance catalysts applied in the synthesis of polyesters from renewable sources. Aliphatic diesters, isosorbide, lactide, tin(II) 2-ethylhexanoate, ytterbium triflate and yttrium triflate were used as starting materials for producing the polymers under study. The tin catalyst, being most common in the literature for this type of system, was used as reference for application of high performance catalysts derived from ytterbium and yttrium. The initial strategy adopted to obtain the reaction conditions to reach the highest molar mass of the polymers was the implementation of an experimental design in order to evaluate how the three main variables - temperature, reaction time and amount of catalyst- influence the polymerization process. Once the direction of the polymerization process was determined based on experimental observations, further empirical adjustments were made in order to optimize the reaction conditions. The products obtained were characterized by size exclusion chromatography, 1H and 13C nuclear magnetic resonance, infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis and mass spectrometry. High efficiency catalysts were used in the preparation of high molecular weight polyesters derived from lactide, aliphatic diesters and sterically hindered diol, the isosorbide. Novel branched polymers were obtained and new mechanism was suggested, allowing a better understanding of the polycondensation reaction for isosorbide derived polymers.
13

Light-emitting hetero-cyclic polymers containing 2, 3, 4, 5- tetraphenylthiophene moiety

Yang, Cheng-Hsien 16 August 2002 (has links)
Polymers containing bulky tetraphenylthiophene (TP) moieties were prepared by different coupling reactions. Firstly, 2,5-bis(4-bromophenyl)-3,4-diphenylthiophene (TP-Br) was coupled together by either NiCl2/PPh3 or n-BuLi to form polymers with TP as the repeat unit. The resulting polymers (PTP-NiCl2 and PTP-BuLi) are easily soluble in organic solvents and are photoluminescent (PL) materials (
14

Synthèse, caractérisation physico-chimique et cinétique de formation des aminoplastes urée-formaldéhyde.

Richard, Brigitte, January 1900 (has links)
Th.--Chim. gén.--Toulouse--I.N.P., 1978. N°: 37.
15

Aplicação de catalisadores de alta eficiência ma síntese de poliésteres derivados de isosorbídeo / Application of high-efficiency catalysts in synthesis of polyesters derived from isosorbide

Fernando Alves Gomes Luengo 28 November 2016 (has links)
O isosorbídeo, juntamente com o ácido láctico, é considerado importante monômero para a preparação de materiais poliméricos derivados de fontes renováveis. O presente trabalho descreve a aplicação de catalisadores de alta eficiência na síntese de poliésteres derivados de fontes renováveis. Diésteres alifáticos, isosorbídeo, lactídeo, 2-etilhexanoato de estanho II (SnOct2), triflato de itérbio [Yb(OTf)3] e triflato de ítrio [Y(OTf)3], foram utilizados como reagentes para a produção dos polímeros em estudo. O catalisador de estanho, por ser o mais comum na literatura para esse tipo de sistema, foi utilizado como referência para a aplicação dos catalisadores de alta eficiência derivados de ítrio e itérbio. A estratégia inicial adotada para a obtenção da maior massa molar possível dos polímeros foi a execução de um planejamento fatorial para avaliação de como três variáveis principais, temperatura, tempo reacional e quantidade de catalisador influenciam o processo de polimerização. Uma vez determinada a direção a ser seguida no processo de polimerização, ajustes empíricos baseados em dados e observações experimentais foram feitos com a finalidade de se otimizar as condições reacionais. Os produtos obtidos foram caracterizados por cromatografia por exclusão de tamanho, ressonância magnética nuclear de 1H e 13C, espectroscopia no infravermelho, calorimetria diferencial de varredura, análise termogravimétrica e espectrometria de massas. Catalisadores de alta eficiência foram utilizados na preparação de poliésteres de alta massa molar, sintetizados a partir de lactídeo, diésteres alifáticos e diol secundário estericamente impedido, o isosorbídeo. Polímeros ramificados inéditos foram obtidos e um novo mecanismo reacional proposto, permitindo uma melhor compreensão sobre o sistema de policondensação para derivados de isosorbídeo. / The isosorbide and lactic acid are considered important monomers from renewable sources for the preparation of biodegradable materials. The present study describes the use of high performance catalysts applied in the synthesis of polyesters from renewable sources. Aliphatic diesters, isosorbide, lactide, tin(II) 2-ethylhexanoate, ytterbium triflate and yttrium triflate were used as starting materials for producing the polymers under study. The tin catalyst, being most common in the literature for this type of system, was used as reference for application of high performance catalysts derived from ytterbium and yttrium. The initial strategy adopted to obtain the reaction conditions to reach the highest molar mass of the polymers was the implementation of an experimental design in order to evaluate how the three main variables - temperature, reaction time and amount of catalyst- influence the polymerization process. Once the direction of the polymerization process was determined based on experimental observations, further empirical adjustments were made in order to optimize the reaction conditions. The products obtained were characterized by size exclusion chromatography, 1H and 13C nuclear magnetic resonance, infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis and mass spectrometry. High efficiency catalysts were used in the preparation of high molecular weight polyesters derived from lactide, aliphatic diesters and sterically hindered diol, the isosorbide. Novel branched polymers were obtained and new mechanism was suggested, allowing a better understanding of the polycondensation reaction for isosorbide derived polymers.
16

A study of a counter-rotating, intermeshing extruder as a polycondensation reactor

Crowe, Edward R. January 1992 (has links)
No description available.
17

Topology and Telechelic Functionality Control in Polyester Design

Ozturk, Gozde 15 July 2009 (has links)
Research efforts have focused on synthesis of linear, long-chain branched, and novel crosslinked polyesters for applications spanning from pressure sensitive adhesives to biomedical applications. Altering polymer topology and functionality using different synthetic strategies was enabled tailoring the thermomechanical, rheological, and adhesive properties of polyesters. The synthesis and characterization of linear, long-chain branched, and crosslinked networks are described focusing on the structure-property relationships. Aliphatic low-Tg polyesters with linear and long-chain branched topology were synthesized using melt polycondensation for pressure sensitive adhesive applications. Relationships between molecular weight, polymer composition, and adhesive performance were investigated. Melt rheological studies and the characterization of adhesive properties indicated that adhesive performance was enhanced with increasing molecular weight. Moreover, a series of long-chain branched low-Tg polyester were investigated to determine the influence of branching and molecular weight. Tailoring the degree of branching enabled the control of rheological and adhesive properties. Characterization of adhesive properties revealed that long-chain branched polymers displayed an enhanced cohesive strength. In addition, utilization of different comonomer compositions allowed tailoring thermal and adhesive properties of low-Tg polyesters over a wide range. Biodegradable networks were synthesized for the first time using base-catalyzed Michael addition of acetoacetate functionalized polyesters with acrylates. Linear and star-shaped poly(caprolactone) (PCL) oligomers with different molecular weights were functionalized and crosslinked. Thermomechanical properties were evaluated as a function of precursor molecular weight and crosslink density. The glass transition temperature and the extent of crystallinity of the networks were dependent on the molecular weight of the PCL segment. Moreover, dynamic mechanical analysis (DMA) indicated that molecular weight of the oligomeric precursors influenced the plateau modulus of the networks as a result of the differences in crosslink density of the networks. In addition, covalently crosslinked networks were synthesized from Michael addition reaction of acetoacetate-functional oligomeric poly(trimethylene succinate)s and poly(trimethylene adipate)s with neopentylglycol diacrylate. The oligomeric polyesters with telechelic hydroxyl functionality were synthesized from renewable monomers, adipic acid, succinic acid, and 1,3-propanediol using melt polycondensation. The molecular weights of the precursors were varied systematically to probe the influence of molecular weight on thermomechanical properties of the networks. The extent of crystallinity and mechanical properties were dependent on the molecular weight of the oligomeric polyester precursors which also controlled crosslink density. Moreover, Michael addition chemistry was utilized to crosslink low-Tg polyesters to improve cohesive strength for PSA applications. In order to determine the influence of temperature and catalyst levels, crosslinking reactions were monitoring using measurement of loss and storage moduli during the reaction. Networks having different levels of gel fractions were investigated to elucidate the influence of degree of crosslinking on thermomechanical and adhesive properties of low-Tg polyesters. / Ph. D.
18

Research and Development of Simulation and Optimization Technology for Commercial Nylon-6 Manufacturing Processes

Seavey, Kevin Christopher 21 April 2003 (has links)
This dissertation concerns the development of simulation and optimization technology for industrial, hydrolytic nylon-6 polymerizations. The significance of this work is that it is a comprehensive and fundamental analysis of nearly all of the pertinent aspects of simulation. It steps through all of the major steps for developing process models, including simulation of the reaction kinetics, phase equilibrium, physical properties, and mass-transfer- limited devolatization. Using this work, we can build accurate models for all major processing equipment involved in nylon-6 production. Contributions in this dissertation are of two types. Type one concerns the formalization of existing knowledge of nylon-6 polymerization mixtures, mainly for documentation and teaching purposes. Type two, on the other hand, concerns original research contributions. Formalizations of existing knowledge include reaction kinetics and physical properties. Original research contributions include models for phase equilibrium, diffusivities of water and caprolactam, and devolatization in vacuum-finishing reactors. We have designed all of the models herein to be fundamental, yet accessible to the practicing engineer. All of the analysis was done using commercial software packages offered by Aspen Technology, Cambridge, MA. We chose these packages for two reasons: (1) These packages enable one to quickly build fundamental steady-state and dynamic models of polymer trains; and (2) These packages are the only ones commercially available for simulating polymer trains. / Ph. D.
19

Copolyéthersulfones rigides-flexibles : modulation des propriétés par modification du segment flexible

Faye, Adrien 24 April 2018 (has links)
La présente thèse traite trois thèmes principaux. Le premier volet concerne le contrôle de la cristallinité et la synthèse des polyéthersulfones avec incorporation de doubles liaisons comme espaceurs dans les chaînes du polymère en utilisant deux approches différentes : la polymérisation par métathèse des diènes acycliques (ADMET) et la polycondensation. L’ADMET a permis d’obtenir des copolymères de faibles polydispersités avec des doubles liaisons régulièrement réparties le long des chaînes du polymère. La polycondensation a permis d’obtenir des copolymères de configuration cis ou trans avec incorporation régulière ou aléatoire des doubles liaisons. Pour la synthèse par ADMET, un bloc rigide, terminé par des groupements allyliques, est polymérisé dans le dichlorométhane à l’aide de l’un des catalyseurs de Grubbs : Grubbs deuxième génération (G2) ou Hoveyda-Grubbs (HG). Concernant la polycondensation, on fait réagir un bloc rigide avec un segment flexible de configuration cis ou trans pour obtenir respectivement le copolymère cis ou trans. La diffraction des rayons X et l’analyse enthalpique différentielle (DSC) ont montré que l’isomère cis inhibe complètement la cristallinité alors que la forme trans la favorise. Le deuxième volet de ce travail repose principalement sur la polycondensation en un seul pot « one pot en anglais» qui a permis de contrôler les températures de transition vitreuse. La spectrométrie de masse MALDI-TOF a permis de démontrer que les copolymères obtenus avec variation du ratio bloc rigide/segment flexible sont de nature aléatoire et non des copolymères blocs. Le troisième et dernier thème de ce document concerne principalement le contrôle de l’hydrophilicité par une post-fonctionnalisation des copolymères à travers les doubles liaisons incorporées en utilisant les réactions thiol-ène clic. Le but étant de moduler les propriétés des copolymères pour les adapter à des applications bien définies. Pour une application dans la filtration membranaire par exemple, des chaînes hydrophiles ont été greffées à travers ces doubles liaisons pour augmenter l’hydrophilicité des copolymères. / This thesis deals with three main themes. The first component relates to the control of the crystallinity and the synthesis of polyethersulfones with incorporation of double bonds as a spacer in the polymer chains using two different approaches: ADMET (Acyclic Diene Metathesis Polymerization) and polycondensation reactions. ADMET leads to copolymers with low polydispersity index and double bonds regularly distributed along the polymer chains. Polycondensation allows obtaining directly cis or trans configuration copolymers with regular or random incorporation of the double bonds. For the synthesis by ADMET, a rigid block terminated by allyl groups is dissolved in dichloromethane and then polymerized using second generation Grubbs catalyst (G2) and Hoveyda-Grubbs catalyst (HG). Concerning the polycondensation reaction, a rigid block reacts with a flexible segment of cis or trans configuration to respectively give the cis or trans copolymer. X-ray diffraction and differential scanning calorimetry (DSC) showed that the cis isomer inhibits crystallization while the trans form favors it. The second part of this work is mainly based on the one-pot polycondensation reaction which allowed control the glass transition. MALDI-TOF mass spectrometry was used to show that copolymers obtained by the variation of the rigid bloc/flexible segment ratio are random and not block copolymers. The third subject of this document mainly concerns the control of the hydrophilicity by post-functionalization of copolymers through the double bonds incorporated using thiol-ene click reactions. The main goal is to modulate the properties of copolymers to suit well-defined applications. For example, for applications in membrane filtration, hydrophilic chains were grafted through double bonds to increase the copolymer hydrophilicity.
20

Synthèse et étude des propriétés physico-chimiques des poly(butylène succinate)s linéaire et branché / Synthesis and study of the physico-chemical properties of the linear and branched poly(butylene succinate)s

Garin, Matthieu 03 December 2012 (has links)
Le poly(butylène succinate) (PBS) est un polyester aliphatique biodégradable dont les propriétés en font un bon candidat pour le remplacement des polyoléfines. De plus, ses deux monomères, l'acide succinique et le butane-1,4-diol, peuvent être issus de la biomasse via un procédé de fermentation de sucres. L'étude réalisée ici a été séparée en deux grandes parties : le PBS linéaire d'une part et le PBS branché d'autre part. La première partie montre que la cinétique de synthèse du PBS suit bien le modèle d'estérification établi par Flory. Par la suite, l'étude des propriétés physico-chimiques du PBS a permis de remonter à des paramètres comme la masse molaire critique d'enchevêtrement, le module du plateau caoutchoutique, l'énergie d'activation du PBS fondu ou encore les paramètres de l'équation Mark-Houwink-Sakurada. Une étude sur ses propriétés thermiques a permis de décrire l'évolution de son comportement en fonction de sa masse molaire. Enfin, le profil d'énergie potentielle de l'estérification entre l'acide succinique et le butane-1,4-diol a été tracé en utilisant un outil de chimie quantique. La seconde partie traite de l'étude de PBS branchés obtenus en employant des agents de branchement (polyols) pouvant être issus de la biomasse comme l'huile de ricin, le glycérol et le polyglycérol. La stratégie adoptée a été le couplage entre un oligomère PBS fonctionnalisé acide carboxylique et les agents de branchement. L'étude en présence d'huile de ricin a mis en avant les relations entre la structure, déterminée en SEC-Triple Détection, et les propriétés physico-chimiques du PBS branché. L'optimisation de la synthèse en présence de glycérol ou de polyglycérol a été abordée à partir de la méthode des plans d'expériences. Comparé à la méthode « un facteur à la fois », des résultats prometteurs et semblables à ce qui est rapporté dans la littérature ont été obtenus pour l'étude du PBS branché en présence de glycérol. / Poly(butylene succinate) (PBS) is a biodegradable aliphatic polyester whose properties make it a promising polymer for the replacement of polyolefins. Moreover, its two monomers, succinic acid and 1,4-butanediol, can be produced via a fermentation process of sugars. This study has been separated into two great parts: linear PBS on the one hand and branched PBS on the other hand. In the first part, kinetics of the PBS synthesis showed a good agreement with the esterification model of Flory. We determined some fundamental parameters of PBS like critical molecular weight of entanglement, the rubbery plateau modulus, the energy of activation of melt PBS and parameters of the Mark-Houwink-Sakurada relationship. We have also realized a study on the influence of the molecular weight on the thermal properties of PBS. Finally, we constructed the potential energy profile of the esterification between succinic acid and 1,4-butanediol through a quantum chemistry study. The second part dealt with the study of branched PBS in the presence of biosourced polyols like castor oil, glycerol and polyglycerol. These syntheses were realized between an acid-functionalized PBS oligomer and the branching agents. We put forward the relationships between the structure, determined by SEC-Triple Detection, and the physicochemical properties of branched PBS in presence of castor oil. Syntheses of branched PBS in presence of glycerol or polyglycerol were optimized with design of experiments technique. Promising and similar results from the literature were obtained in the case of branched PBS in presence of glycerol compared to the method of “one parameter at a time”.

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