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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.
191

Obtenção de microcápsulas poliméricas contendo um agente formador de filme em seu núcleo para o desenvolvimento de revestimentos autorreparadores. / Development of polymeric microcapsules containing a film-forming agent to design self-healing coatings.

Cotting, Fernando 19 October 2017 (has links)
A aplicação de uma ou mais camadas de tinta sobre as superfícies metálicas é a maneira mais comum e eficaz de proteger os substratos metálicos contra o fenômeno da corrosão. No entanto, os sistemas de pintura podem vir a falhar precocemente por diferentes motivos, causando um ataque corrosivo inesperado no metal a ser protegido. Por esta razão, o processo de repintura em estruturas metálicas é realizado frequentemente para garantir a integridade da estrutura pintada e aumentar sua vida útil. Como o processo de repintura gera impactos econômicos e ambientais, sistemas de pintura capazes de sofrerem uma reparação sem a necessidade de uma intervenção humana, precisam ser desenvolvidos. O encapsulamento de agentes de reparação, com propriedades de formação de filme, em microcápsulas poliméricas é uma excelente alternativa para que os sistemas de pintura se autorreparem, aumentando os intervalos de repintura. Após o processo de encapsulamento, as microcápsulas contendo o agente de reparação são incorporadas na preparação da tinta, para que o sistema de pintura seja aplicado sobre a estrutura metálica. Este tipo de aditivação confere ao revestimento a propriedade de autorreparação, pois quando o sistema de pintura é danificado as microcápsulas são rompidas e liberam o agente de reparação no local danificado, protegendo novamente o substrato metálico. Neste trabalho foi desenvolvido um sistema autorreparador monocomponente, através do microencapsulamento de uma resina a base de éster de epóxi, pelo método de polimerização in-situ. Também foi desenvolvido um sistema autorreparador bicomponente, através do microencapsulamento de uma resina a base de epóxi, pelo método de emulsão e polimerização in-situ de ureia-formaldeído-melamina e do seu endurecedor a base de poliamida, pelo método de extração de solvente em paredes de poliestireno. Foi realizado um planejamento estatístico para estudar a emulsão precursora das microcápsulas de poli(ureia-formaldeído-melamina) contendo o sistema monocomponente, onde foram estudados: o tipo e a velocidade de agitação, a presença de cloreto de sódio na formulação, o uso de uma sonda ultrassônica após a etapa de dispersão, a concentração de tensoativo na formulação e o tensoativo utilizado. Como variáveis de resposta foram determinadas: a estabilidade visual das emulsões e o diâmetro das gotículas formadas. A melhor condição de emulsificação determinada foi utilizada para a obtenção das microcápsulas de poli(ureia-formaldeídomelamina) contendo a resina éster de epóxi e das microcápsulas de poli(ureiaformaldeído-melamina) contento a resina epóxi. Entre as condições de emulsificação estudadas, apenas a condição utilizando o tensoativo goma arábica possibilitou a obtenção das microcápsulas de poli(ureia-formaldeído-melamina) na faixa de diâmetro desejada. O método escolhido para o encapsulamento do endurecedor possibilitou a obtenção de microcápsulas de poliestireno, porém com uma baixa capacidade de armazenamento. A liberação dos agentes de reparação encapsulados foi observada pela microscopia óptica e comprovada pela técnica de espectroscopia na região do infravermelho (FTIR) e pela técnica de espectroscopia Raman. Os aditivos autorreparadores desenvolvidos (mono e bicomponente) foram adicionados separadamente em uma tinta epóxi, nas proporções mássicas em base seca de 10 e 15 %. O sistema de pintura foi aplicado em um esquema de três camadas e o aditivo de autorreparação foi incorporado na primeira e/ou segunda camada aplicada. O sistema de pintura contendo o aditivo autorreparador monocomponente apresentou um aspecto visual melhor do que o sistema de pintura contendo o aditivo autorreparador bicomponente, porém o sistema bicomponente forneceu melhores propriedades de aderência, de impermeabilidade, anticorrosivas e de autorreparação à tinta aditivada. As medidas com as técnicas eletroquímicas de espectroscopia de impedância eletroquímica (EIE) e de varredura com eletrodo vibratório (SVET) comprovaram que os dois aditivos desenvolvidos proporcionaram o efeito autorreparador aos sistemas de pintura aditivados, quando estes foram danificados mecanicamente com uma microbroca ou com um estilete. Ensaios acelerados de corrosão em câmara de névoa salina e ensaios de exposição ao intemperismo natural mostraram que os aditivos desenvolvidos promoveram uma proteção adicional ao aço carbono, quando o sistema de pintura foi danificado mecanicamente. / The application of one or more coating layers on the metallic surfaces is the most common and effective way to protect metallic substrates against corrosion. Nevertheless, the coating layer may fail early for different reasons, leading to an unexpected corrosive attack on the protected metal. For this reason, the coating repair process is performed to ensure the integrity during the service life of the coated metallic structures. Due to the fact that coating repair process generates economic and environmental impacts; there is a great need for the development of systems capable to repair themselves, without human intervention. The encapsulation of repairing agents, with film forming properties, in polymeric microcapsules is an excellent alternative to the coating self-repair, decreasing the coating repair process frequency. After the encapsulation process, the microcapsules containing the repair agent are incorporated into the paint preparation and the coating system could be applied normally to the metallic surface. This kind of additivation confers to the coating the self-healing property, because when the coating system is damaged the microcapsules suffers a rupture and release the repair agent into the damaged site, protecting the metallic substrate from corrosion. In this work, a mono-component self-healing system was developed, through the microencapsulation of an epoxy ester resin, by the in-situ polymerization method. A bi-component self-healing system was also developed, by the microencapsulation of an epoxy resin, through the emulsion and in-situ polymerization method and by the microencapsulation of a polyamide hardener, by the double emulsion and solvent extraction method. A factorial design was developed to study the precursor emulsion of the poly (urea-formaldehyde-melamine) microcapsules containing the monocomponent system, where the studied factors were: the type and speed of the agitation, the presence of sodium chloride in the formulation, the use of an ultrasonic probe after the emulsification, the surfactant type and concentration. The analyzed response variables were: the visual stability of the emulsions and the mean diameter of the formed droplets. The best obtained emulsification conditions were employed to produce the poly(urea-formaldehyde-melamine) microcapsules containing the epoxy ester resin and poly(urea-formaldehyde-melamine) microcapsules containing the epoxy resin. Among the studied emulsification conditions, only using arabic gum surfactant the poly (urea-formaldehyde-melamine) microcapsules were obtained. The selected method for the hardener encapsulation was efficient to obtain polystyrene microcapsules, but with low loading capacity. The release of the encapsulated repair agents was observed by optical microscopy and confirmed by infrared spectroscopy (FTIR) technique and Raman spectroscopy technique. The developed self-healing additives (mono and bicomponent) were added separately in an epoxy commercial coating, using the dry mass ratios 10% and 15 %. The coating system was applied in a three layer coating system and the self-healing additive was incorporated into the first and/or second layer. The coated samples containing the mono-component additive had a better visual appearance than the bi-component additive system; nevertheless the bi-component system provided better adhesion, impermeability, anti-corrosion and self-healing properties to the doped coating. The electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET) measurements proved that the two developed additives provided self-healing properties to the doped coating systems, when they were mechanically damaged with a micro drill or a blade. Accelerated corrosion tests in the salt spray chamber and natural atmospheric corrosion tests showed that the developed additives provided an additional protection to the carbon steel, when the coating system has been mechanically damaged.
192

Cyanate ester, epoxy and epoxy/cyanate ester matrix polyhedral oligomeric silsesquioxane nanocomposites

Liang, Kaiwen. January 2005 (has links)
Thesis (Ph.D.) -- Mississippi State University. Dave C. Swalm School of Chemical Engineering.. / Title from title screen. Includes bibliographical references.
193

Production Of Epoxide Functionalized Boehmite Nanoparticles And Their Use In Epoxide Nanocomposites

Coniku, Anisa 01 January 2011 (has links) (PDF)
In the present study the effects of addition of organically functionalized boehmite nano-particles on the mechanical properties of epoxy polymers were analyzed. Nanosize platelets of boehmite powders were produced via a hydrothermal process from the raw material aluminum trihydroxide Al(OH)3 provided by a a chemical supplier, but which in future studies can be replaced by local resources of aluminum trihydroxide available in Seydisehir, Turkey. The ground aluminum trihydroxide particles were submitted to a two-step preliminary ageing procedure in different pH media. Particles were then converted to boehmite nanoparticles via hydrothermal ageing at high pressure and temperature. The product&lsquo / s chemical identity, size, structure and morphology were characterized with XRD, FT-IR, SEM and PSA analyses. By controlling the pH and the ageing time as parameters, hexagonal shaped nanoplatelets were obtained with dimensions ranging from 100 to 500 nm. Aiming at using these nanoparticles into surface coating polymers, the most favorable shape is the plate-like morphology, leading to adopting the last hydrothermal condition in the rest of the study. v The boehmite crystal surfaces are furnished with hydroxyls which can potentially be reacted with epoxy monomers of bisphenol A diglycidyl ether with the help of tin (II) chloride as catalyst through ring-opening reactions. The FT-IR and quantitative analyses indicated that this surface functionalization is possible under a temperature 80 oC and a weight ratio of 5:1 epoxy monomer to boehmite powder These novel inorganic/organic hybrid materials were then mixed with epoxy/hardener resin mixture to obtain nanocomposites. The properties of the composites were characterized accordingly with tensile, impact, micro hardness, micro-scratch tests, DMA analysis and observed with SEM analysis. A deterioration of the tensile strength from the neat polymer was observed, with a distinct trend between the functionalized and non-functionalized boehmite-epoxy polymers. The functionalized polymers showed a less deteriorative character. The tensile modulus instead showed a little improvement of (4%) in 5wt% loaded polymers. DMA analysis results revealed an improved glass transition temperature in the nanocomposites as well as in storage and loss modulus. As aimed in this work, the functionalized boehmite-epoxy polymers displayed a clear improvement in comparison to both non-functionalized and neat polymers in surface coating properties in hardness and scratch resistance.
194

Determination of the dimensional accuracy of epoxy resin and polyurethane dental die materials a thesis submitted in partial fulfillment ... prosthodontics ... /

Luke, Joseph T. January 1988 (has links)
Thesis (M.S.)--University of Michigan, 1988.
195

Determination of the dimensional accuracy of epoxy resin and polyurethane dental die materials a thesis submitted in partial fulfillment ... prosthodontics ... /

Luke, Joseph T. January 1988 (has links)
Thesis (M.S.)--University of Michigan, 1988.
196

Investigation of the curing process of an epoxy/silica composite for microelectronics / Etude du procédé de réticulation d'un composite époxy/silice pour les applications en microélectronique

Granado, Lérys 17 November 2017 (has links)
En raison de la demande de miniaturisation croissante dans l’industrie microélectronique, il est nécessaire de développer des circuits imprimés multicouches (PCB, Printed Circuit Board) présentant une densité d’interconnections de plus en plus élevée. Avec leurs bonnes propriétés physico-chimiques et mécaniques et un relatif faible coût, les matériaux composites à base de résine époxy sont des matériaux de premier choix pour ce type d’application. Cependant, la réduction de la taille des connexions électriques de cuivre (largeur < 1 µm), implique que l’adhésion cuivre/époxy soit améliorée. Dans la littérature, des études ont montré que le taux de réticulation des résines epoxy est un paramètre clé, contrôlant la résistance chimique de la résine epoxy (vis-à-vis des procédés industriels d’impression de cuivre par voie chimique) et les propriétés d’adhésion du cuivre sur le substrat composite.L’objectif de cette thèse est d’étudier de façon approfondie la cinétique de réticulation d’un composite époxy/silice (ABF) utilisé en production de masse dans l’industrie microélectronique afin de proposer un protocole de fabrication des circuits imprimés en fonction du taux de réticulation.Le comportement rhéologique du matériau composite en fonction du taux de réticulation a été étudié par analyse mécanique dynamique (DMA). L’influence du taux de réticulation sur les processus de gélification et de vitrification est présentée et une analyse du comportement viscoélastique de la résine epoxy près de la transition vitreuse est discutée. Le modèle WLF est utilisé pour décrire la dynamique de réseau du polymère. La cinétique de réticulation du composite a été étudiée in situ en spectroscopie proche-infrarouge (NIR) et en calorimétrie différentielle à balayage (DSC) en modes isotherme et non-isotherme. L’analyse iso-conversionnelle a permis de déterminer l’énergie d’activation de la réaction de réticulation. Cependant, une modélisation plus approfondie de la cinétique de réticulation a été nécessaire en raison d’une contribution de diffusion s’ajoutant à la contribution chimique de la réaction. Cette étude a montré que les cinétiques de réticulation peuvent être décrites par le modèle auto-catalytique d’ordre n combiné aux modèles de Rabinowitch et WLF-modifié, modèles tenant compte de la contribution de diffusion. Ce modèle a permis de prédire le comportement du matériau dans une large gamme temps/température et d’établir le diagramme Température-Temps-Transformation du matériau .Compte tenu de l’importance du taux de réticulation sur les propriétés d’adhésion des connexions électriques de cuivre, une méthode de mesure du taux de réticulation sur des PCB industriels a été développée. La spectroscopie infrarouge en réflexion diffuse (DRIFTS) s’est avérée être une technique d’analyse parfaitement adaptée. L’influence du taux de réticulation sur l’étape de “desmear” du procédé de fabrication a également été étudiée. Cette étape, constituée d’une phase de gonflement de la résine epoxy (swelling) suivie d’une attaque oxydante au permanganate et d’une étape de réduction, est déterminante quant à la rugosité de surface obtenue et donc l’adhésion du cuivre sur le substrat composite. Une méthode originale a été développée pour déterminer le profil de diffusion de l’agent de gonflement (sweller) au sein du matériau, méthode alliant microtomie et analyse chromatographique. L’effet des conditions de “swelling” sur la rugosité finale du matériau a été déterminé par microscopie à force atomique (AFM). Des tests d’adhésion du cuivre ont également été réalisés afin d’étudier l’influence du taux de réticulation de la résine epoxy et de la rugosité de surface du composite sur la force d’adhésion. Finalement, une bonne adhésion du cuivre (environ 4 N/cm) pour des surfaces de faible rugosité (< 10 nm). / Due to the increasing miniaturization in microelectronics the manufacturing of densely interconnected multilayer printed-circuit boards (PCB) is needed. With their well-balanced physico-chemical and mechanical properties and low cost, epoxy-based composites are insulating materials of prime choice. However, to achieve interconnections at a lower scale (copper line width down to ca. 1 µm), the adhesion between the composite substrate and the copper interconnections must be enhanced. Previous studies showed that the degree of curing of the epoxy matrix (i.e. conversion of crosslinking reaction) is one key-parameter, driving the matrix chemical and mechanical resistance (during the PCP manufacturing process) and the composite/copper line adhesion properties.In this work we present and discuss an in-depth study of the curing kinetics of an epoxy/silica composite (ABF) relevant to the microelectronics industry. The final objective is to propose a process protocol of the PCB manufacturing as function of the degree of curing.The rheological behaviour of the composite material is investigated by dynamic mechanical analysis (DMA). The gelation and vitrification mechanisms are presented as a function of the degree of curing. The viscoelastic behavior of the epoxy matrix near the glass-transition is studied and is shown to be well-described by the WLF model.The curing kinetics of the epoxy composite are studied by in situ near-infrared (NIR) spectroscopy and both isothermal and non-isothermal differential scanning calorimetry (DSC). Iso-conversional analyses are performed to determine the apparent activation energy of the curing reaction. Due to a non-negligible contribution of the diffusion part in the curing reaction, further modelling was needed to achieve a complete description of the curing kinetics. This study showed that the curing kinetic is well-described by the nth-order autocatalytic fitting model in combination with the Rabinowitch/modified-WLF models, taking into account the diffusion contribution. This model is used to predict the material behaviour in a wide time/temperature range and to propose a Temperature-Time-Transformation diagram of the material.Due to the influence of the degree of curing on the adhesion of copper electrical lines, an experimental method for the measurement of the degree of curing of industrial PCB was developed. Diffuse-reflectance infrared spectroscopy (DRIFTS) is found to be a versatile and accurate technique. The influence of the degree of curing on the “desmear” step of the PCB manufacturing process is studied as well. The “desmear” step proceeds in the swelling of the epoxy matrix and the subsequent permanganate etching and reduction reactions. The “desmear” step is quite important regarding the composite surface roughness and, as a consequence, the adhesion of the copper lines. An original method for the determination of the diffusion profile of the sweller through the depth of the material was developed using microtomy and chromatography. The effect of swelling experimental parameters on the final roughness of the composite is determined by atomic force microscopy (AFM). Adhesion tests of copper lines on the composite substrate are performed to study the influence of the initial degree of curing and the roughness on the peel strength. Good adhesion of copper (about 4 N/cm) is achieved for a low substrate roughness (< 10 nm).
197

Obtenção de microcápsulas poliméricas contendo um agente formador de filme em seu núcleo para o desenvolvimento de revestimentos autorreparadores. / Development of polymeric microcapsules containing a film-forming agent to design self-healing coatings.

Fernando Cotting 19 October 2017 (has links)
A aplicação de uma ou mais camadas de tinta sobre as superfícies metálicas é a maneira mais comum e eficaz de proteger os substratos metálicos contra o fenômeno da corrosão. No entanto, os sistemas de pintura podem vir a falhar precocemente por diferentes motivos, causando um ataque corrosivo inesperado no metal a ser protegido. Por esta razão, o processo de repintura em estruturas metálicas é realizado frequentemente para garantir a integridade da estrutura pintada e aumentar sua vida útil. Como o processo de repintura gera impactos econômicos e ambientais, sistemas de pintura capazes de sofrerem uma reparação sem a necessidade de uma intervenção humana, precisam ser desenvolvidos. O encapsulamento de agentes de reparação, com propriedades de formação de filme, em microcápsulas poliméricas é uma excelente alternativa para que os sistemas de pintura se autorreparem, aumentando os intervalos de repintura. Após o processo de encapsulamento, as microcápsulas contendo o agente de reparação são incorporadas na preparação da tinta, para que o sistema de pintura seja aplicado sobre a estrutura metálica. Este tipo de aditivação confere ao revestimento a propriedade de autorreparação, pois quando o sistema de pintura é danificado as microcápsulas são rompidas e liberam o agente de reparação no local danificado, protegendo novamente o substrato metálico. Neste trabalho foi desenvolvido um sistema autorreparador monocomponente, através do microencapsulamento de uma resina a base de éster de epóxi, pelo método de polimerização in-situ. Também foi desenvolvido um sistema autorreparador bicomponente, através do microencapsulamento de uma resina a base de epóxi, pelo método de emulsão e polimerização in-situ de ureia-formaldeído-melamina e do seu endurecedor a base de poliamida, pelo método de extração de solvente em paredes de poliestireno. Foi realizado um planejamento estatístico para estudar a emulsão precursora das microcápsulas de poli(ureia-formaldeído-melamina) contendo o sistema monocomponente, onde foram estudados: o tipo e a velocidade de agitação, a presença de cloreto de sódio na formulação, o uso de uma sonda ultrassônica após a etapa de dispersão, a concentração de tensoativo na formulação e o tensoativo utilizado. Como variáveis de resposta foram determinadas: a estabilidade visual das emulsões e o diâmetro das gotículas formadas. A melhor condição de emulsificação determinada foi utilizada para a obtenção das microcápsulas de poli(ureia-formaldeídomelamina) contendo a resina éster de epóxi e das microcápsulas de poli(ureiaformaldeído-melamina) contento a resina epóxi. Entre as condições de emulsificação estudadas, apenas a condição utilizando o tensoativo goma arábica possibilitou a obtenção das microcápsulas de poli(ureia-formaldeído-melamina) na faixa de diâmetro desejada. O método escolhido para o encapsulamento do endurecedor possibilitou a obtenção de microcápsulas de poliestireno, porém com uma baixa capacidade de armazenamento. A liberação dos agentes de reparação encapsulados foi observada pela microscopia óptica e comprovada pela técnica de espectroscopia na região do infravermelho (FTIR) e pela técnica de espectroscopia Raman. Os aditivos autorreparadores desenvolvidos (mono e bicomponente) foram adicionados separadamente em uma tinta epóxi, nas proporções mássicas em base seca de 10 e 15 %. O sistema de pintura foi aplicado em um esquema de três camadas e o aditivo de autorreparação foi incorporado na primeira e/ou segunda camada aplicada. O sistema de pintura contendo o aditivo autorreparador monocomponente apresentou um aspecto visual melhor do que o sistema de pintura contendo o aditivo autorreparador bicomponente, porém o sistema bicomponente forneceu melhores propriedades de aderência, de impermeabilidade, anticorrosivas e de autorreparação à tinta aditivada. As medidas com as técnicas eletroquímicas de espectroscopia de impedância eletroquímica (EIE) e de varredura com eletrodo vibratório (SVET) comprovaram que os dois aditivos desenvolvidos proporcionaram o efeito autorreparador aos sistemas de pintura aditivados, quando estes foram danificados mecanicamente com uma microbroca ou com um estilete. Ensaios acelerados de corrosão em câmara de névoa salina e ensaios de exposição ao intemperismo natural mostraram que os aditivos desenvolvidos promoveram uma proteção adicional ao aço carbono, quando o sistema de pintura foi danificado mecanicamente. / The application of one or more coating layers on the metallic surfaces is the most common and effective way to protect metallic substrates against corrosion. Nevertheless, the coating layer may fail early for different reasons, leading to an unexpected corrosive attack on the protected metal. For this reason, the coating repair process is performed to ensure the integrity during the service life of the coated metallic structures. Due to the fact that coating repair process generates economic and environmental impacts; there is a great need for the development of systems capable to repair themselves, without human intervention. The encapsulation of repairing agents, with film forming properties, in polymeric microcapsules is an excellent alternative to the coating self-repair, decreasing the coating repair process frequency. After the encapsulation process, the microcapsules containing the repair agent are incorporated into the paint preparation and the coating system could be applied normally to the metallic surface. This kind of additivation confers to the coating the self-healing property, because when the coating system is damaged the microcapsules suffers a rupture and release the repair agent into the damaged site, protecting the metallic substrate from corrosion. In this work, a mono-component self-healing system was developed, through the microencapsulation of an epoxy ester resin, by the in-situ polymerization method. A bi-component self-healing system was also developed, by the microencapsulation of an epoxy resin, through the emulsion and in-situ polymerization method and by the microencapsulation of a polyamide hardener, by the double emulsion and solvent extraction method. A factorial design was developed to study the precursor emulsion of the poly (urea-formaldehyde-melamine) microcapsules containing the monocomponent system, where the studied factors were: the type and speed of the agitation, the presence of sodium chloride in the formulation, the use of an ultrasonic probe after the emulsification, the surfactant type and concentration. The analyzed response variables were: the visual stability of the emulsions and the mean diameter of the formed droplets. The best obtained emulsification conditions were employed to produce the poly(urea-formaldehyde-melamine) microcapsules containing the epoxy ester resin and poly(urea-formaldehyde-melamine) microcapsules containing the epoxy resin. Among the studied emulsification conditions, only using arabic gum surfactant the poly (urea-formaldehyde-melamine) microcapsules were obtained. The selected method for the hardener encapsulation was efficient to obtain polystyrene microcapsules, but with low loading capacity. The release of the encapsulated repair agents was observed by optical microscopy and confirmed by infrared spectroscopy (FTIR) technique and Raman spectroscopy technique. The developed self-healing additives (mono and bicomponent) were added separately in an epoxy commercial coating, using the dry mass ratios 10% and 15 %. The coating system was applied in a three layer coating system and the self-healing additive was incorporated into the first and/or second layer. The coated samples containing the mono-component additive had a better visual appearance than the bi-component additive system; nevertheless the bi-component system provided better adhesion, impermeability, anti-corrosion and self-healing properties to the doped coating. The electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET) measurements proved that the two developed additives provided self-healing properties to the doped coating systems, when they were mechanically damaged with a micro drill or a blade. Accelerated corrosion tests in the salt spray chamber and natural atmospheric corrosion tests showed that the developed additives provided an additional protection to the carbon steel, when the coating system has been mechanically damaged.
198

De la définition à la mise en forme de feutres imprégnés expansés à base de formules résineuses répondant aux exigences de REACH / From the definition to the processing of REACH compliant polymer reinforced by basalt fibres and expanded

El Gazzani, Samira 10 November 2016 (has links)
Ces travaux ont été réalisés dans le cadre d’un projet industriel avec l’entreprise Roxel visant à la substitution de la résine phénolique, impactée par la règlementation Reach, dans un matériau composite expansé : le Roxalte®. Ce matériau est composé d’un feutre de basalte imprégné de résine phénolique qui s’expanse sous l’effet de la température par l’action de microsphères expansibles contenu dans le mélange (Expancel®). Pour s’adapter aux différentes utilisations du Roxalte®, des systèmes époxy répondant aux exigences de Reach ont été sélectionnés. Le premier objectif de cette thèse est la substitution de la résine phénolique. Le second objectif est de fournir une méthodologie pour la réalisation de mousses. La caractérisation physicochimique de la résine phénolique ainsi qu’une étude des relations structure/propriétés ont orienté la sélection vers un système faisant état de très hautes Tg : le Tris(4-hydroxyphenyl) methane triglycidyl ether (TETM) allié au durcisseur amine diaminodiphénylsulfone (DDS). La solution de remplacement immédiate a alors consisté à utiliser le système époxy [TETM/DDS] ainsi qu’un grade d’Expancel® adapté à l’intervalle de polymérisation de la résine. L’optimisation du cycle de réticulation a permis d’atteindre une Tg égale à 330 °C. La seconde étape a consisté à optimiser le moussage en calant la cinétique de réticulation sur la cinétique d’expansion par la détermination des temps de gel du système époxy et des temps d’expansion des microsphères. En dernier lieu, le composite expansé a été mis en œuvre grâce à l’ajout de solvant non réactif (acétone). Le deuxième volet de ces travaux a porté sur l’étude du moussage en utilisant le bicarbonate de sodium (BS) comme agent gonflant. La dualité exothermique/endothermique du procédé (exothermie de la réticulation et endothermie de la décomposition du BS) a été étudiée. Des suivis cinétique en mode isothermes et anisotermes ont été réalisés sur deux systèmes époxy (TETM/DDS et TETM/IPDA), sur le BS et sur les mélanges TETM/DDS+BS et TETM/IPDA+BS. L’ajout de fibres de basalte a fait état de différence notable sur la morphologie des mousses à base des systèmes époxy et du BS et les phénomènes de coalescence des bulles et de diffusion du gaz ont été mis en évidence. Une meilleure répartition des fibres et des bulles avec le système [TETM/IPDA] a été observé. / This work was performed within the framework of an industrial project of Roxel company. The project aim was the substitution of phenolic resin in an expanded composite material: the Roxalte®. This material is made of basalt mat impregnated by phenolic resin which expands under heating by the action of expandable microspheres (Expancel®). The second objective of this work is to provide a methodology for foaming optimization. REACH compliant epoxy resins were selected as substitute. Our choice was guided by the physical-chemical characterization of phenolic resin and the study of structure-property relationship. A high glass transition temperature system has been selected: the Tris(4-hydroxyphenyl)methane triglycidyl ether (TETM) with amine hardener diaminodiphenylsulfone (DDS). The immediate alternative solution consisted of epoxy system [TETM/DDS] and appropriate Expancel® microspheres. The microspheres have been chosen according to the curing temperature interval of the resin. The curing process optimization has been achieved and a Tg equal to 330 °C has been reached. Then the temperature that leads to equilibrium between the microsphere’s foaming kinetic and the resin gelation kinetic has been determined. The second part of this work deals with the study of foaming process using sodium bicarbonate (SB) as foaming agent. The exothermic-endothermic duality of the process (exothermicity of polymerization and endothermicity of SB decomposition) has been studied. Reaction kinetics of epoxy resins (TETM/DDS and TETM/IPDA), SB and mixes (TETM/DDS+BS and TETM/IPDA+BS) have been followed in isothermal and non-isothermal modes. Morphologies differences between TETM/DDS+BS and TETM/IPDA+BS systems and coalescence and diffusion phenomena have been observed when basalt fibers was added. Improved fibers distribution in TETM/IPDA system have been revealed.
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Stabilizace epoxidových systémů v povrchových ochranných nátěrech / Stabilizing epoxide systems in surface protective varnishes

Švardala, Daniel January 2021 (has links)
The diploma thesis describes the influence of humid conditions on the curing of epoxy resins by multifunctional amines. The aim of the experimental part was the identification of degradation products and their quantification, as well as the determination of the influence of humid conditions on the degree of hardening, modulus of elasticity, and flexural strength. Another goal was to optimize the formulation of the reactive mixture for the preparation of epoxy resin with lower susceptibility to carbamate bloom. The degradation products were evaluated by determining the mechanical properties by bending test according to the standard ČSN EN 179-1. The degree of hardening was monitored through temperature modulated differential scanning calorimetry (TMDSC). Degradation products were identified by Fourier transform infrared spectroscopy (FTIR) and quantified by UV-VIS spectroscopy. The morphology of the surface layer was monitored by confocal laser scanning microscopy (CLSM). The dependence of the relative humidity of the environment on the curing process of the epoxy resin and its resulting mechanical properties was determined. Based on the analyzes, a modification of the formulation for the suppression of spurious carbamate during the curing of the epoxy matrix was designed and experimentally verified.
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Design et synthèse de nouveaux sels organiques pour le développement de polyélectrolytes / Design and synthesis of new organic salts for the development of polyelectrolytes

Chardin, Charline 18 December 2018 (has links)
Depuis le début du 21ème siècle, les liquides ioniques (LIs) représentent une importante source d'innovation dans la recherche académique et industrielle en chimie puisqu'ils peuvent être synthétisés, modulés puis utilisés dans de nombreuses applications. De par leurs avantages, les LIs font l'objet d'un véritable engouement dans le domaine des matériaux polymères. Ainsi, ce travail décrit la synthèse de sels organiques originaux pour le développement de polyélectrolytes inédits. Pour cela, nous avons développé de nouvelles voies d'accès à des imidazoliums fonctionnalisés par des fonctions époxydes par l’utilisation d'une méthodologie d'oxydation efficace, flexible et transposable sur une échelle de plusieurs grammes. L'analyse thermique de ces sels a dévoilé une excellente stabilité thermique jusqu'à 400 °C et une température de transition vitreuse basse généralement comprise entre -60 °C et -26 °C. A la suite de ces résultats, la stratégie a été élargie aux anions afin de proposer des fonctions époxydes associées à des sulfonimides inédits. Au cours de cette deuxième phase, l'insertion de fonctions époxydes sur l'anion sulfonimide a été réalisée avec succès permettant un accès à différents prépolymères comme un cation/anion triépoxyde. Dans une deuxième partie, nous avons réalisé une étude mécanistique en utilisant un sel monoépoxyde en présence de différentes amines pour identifier les principaux sites actifs lors de la polymérisation. Grace à ces informations, nous avons confirmé la stabilité de l’imidazolium et la très bonne réactivité de l’époxyde vis-à-vis de diverses amines conduisant à une meilleure compréhension de l'architecture globale du réseau. A partir de ces travaux, un réseau époxy inédit a été mis en œuvre en collaboration avec le laboratoire d'ingénierie des matériaux polymères (IMP) de l'INSA de Lyon. Pour cela, un sel diépoxyde a été sélectionné puis copolymérisé avec un durcisseur diamine (Jeffamine D230) afin de concevoir des réseaux époxy/amine flexibles présentant des propriétés très intéressantes par rapport aux réseaux époxy classiques. / Since the beginning of the 21th century, Ionic liquids (ILs) have been an important source of innovation in chemical academic and industrial research because they can be synthesized, modulated and used then in many applications. Because of their advantages, ILs are of great interest in the field of polymer materials. Thus, this work describes the synthesis of original organic salts to develop innovative polyelectrolytes. For this, we have developed new routes to access to imidazolium salts functionalized by reactive epoxide functions thanks to the development of an effective and flexible oxidative methodology, feasible on a large scale. The thermal analysis of this salts revealed a very good thermal stability up to 400°C and a low glass transition temperature between -60 °C and -26 °C generally. Following these results, the study was extended to anions to provide epoxides associated with novel sulfonimides. During this second phase, the insertion of epoxide functions on the sulfonimide anion was successfully carried out allowing access to different prepolymers such as a triepoxide cation/anion. In a second part, we carried out a mechanistic study using a monoepoxide salt in the presence of different amines to identify the main active sites during the polymerization. According to this information, we have confirmed the stability of the imidazolium and the very good reactivity of the epoxide with various amines leading to a better understanding of the overall architecture of the network. From this work, a novel epoxy network was prepared in collaboration with the polymer materials engineering laboratory (IMP) of INSA of Lyon. For this, a diepoxide salt was selected and copolymerized in the presence of a diamine hardener (Jeffamine D230) in order to design flexible epoxy/amine networks having very interesting properties in comparison with conventional epoxy networks.

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