Made available in DSpace on 2016-12-08T17:19:34Z (GMT). No. of bitstreams: 1 01_Capa_Sumario.pdf: 97224 bytes, checksum: 84cdd855f48b9820d3374a610091b98c (MD5) Previous issue date: 2010-02-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The main goal of this work was the synthesis of silsesquioxane oligomers containing amine and phenyl groups, and the subsequent formation of an organic-inorganic hybrid by reaction of amine groups of the silsesquioxane precursor with the epoxy rings of bisphenol A diglycidyl ether (BADGE). The sol-gel process adopted in the oligomers syntheses proved to be efficient for the condensation reaction between 3-aminopropyltriethoxysilane and phenyltriethoxysilane. Epoxy-silsesquioxane hybrids prepared from oligomers with different condensation degrees were studied. These matrices were further reinforced with 0.25 % (w/w) of multi-walled carbon nanotube (MWCNT). Resin transfer molding (RTM) was also used to produce reinforced nanocomposites with carbon fiber (CF) and MWCNT (0.25 and 0,50 % (w/w)). Liquid state 29Si nuclear magnetic resonance analysis indicated that T3 structure is the major phase forming the synthesized oligomer. Infrared spectroscopy analyses confirmed the formation of epoxy-copolysilsesquioxane hybrid and showed that a high degree of cure was achieved after the addition of an aliphatic polyamine, however, an increase in thermal stability of produced hybrids was not observed. Glass transition temperatures (Tg) obtained by dilatometry and DMA did not show a trend of increase or decrease in this property for the produced hybrids by casting. The cured hybrids presented a brittle type fracture, similar to epoxy resin. The addition of MWCNT to the hybrid matrix did not influence the tensile mechanical properties (Young modulus and tensile strength) and caused a reduction in the Tg of the nanocomposites. Good wettability of CF by resin was observed in the nanocomposites obtained by RTM, providing significant increases in mechanical properties under tensile and impact, however, the Tg s decreased by 30 % in relation to epoxy. Unlike casting molding, the addition of MWCNT in the RTM process provided a significant increase in the mechanical properties analyzed. / Este trabalho teve por objetivo a síntese de oligômeros de silsesquioxanos contendo grupos amino e fenil, e a posterior formação de um híbrido orgânico-inorgânico pela reação dos grupos amino do precursor silsesquioxano com o anel epoxídico da resina diglicidil éter de bisfenol A (DGEBA). O processo sol-gel adotado na síntese dos oligômeros demonstrou ser eficiente na reação de condensação entre o 3-aminopropiltrietoxissilano e feniltrietoxissilano. Matrizes híbridas com silsesquioxanos de diferentes graus de condensação foram estudadas. A estas matrizes foram adicionados 0,25 % (m/m) de nanotubos de carbono de paredes múltiplas (MWCNT). A moldagem por transferência de resina (RTM) foi utilizada na produção de nanocompósitos reforçados com fibra de carbono (CF) e MWCNT (0,25 e 0,50 % (m/m)). Análise de ressonância magnética nuclear 29Si em solução revelou que o sítio T3 é a maior fase constituinte do oligômero sintetizado. Espectroscopia de infravermelho confirmou a formação do híbrido epóxidocopolissilsesquioxano e mostrou que um alto grau de cura foi atingido após a adição de uma poliamina alifática, contudo, não se observou aumento na estabilidade térmica dos híbridos produzidos. As temperaturas de transição vítrea (Tg) obtidas por dilatometria e DMA não apresentaram uma tendência de aumento ou decréscimo nesta propriedade dos híbridos produzidos por casting. Os híbridos curados apresentaram caráter de fratura do tipo frágil, semelhante à resina epoxídica. A adição de MWCNT às matrizes híbridas não influenciou as propriedades mecânicas sob tração (módulo de elasticidade e tensão máxima) e provocou uma diminuição da Tg nos respectivos nanocompósitos. Uma boa molhabilidade das CF pela resina foi observada nos nanocompósitos obtidos por RTM proporcionando aumentos expressivos nas propriedades mecânicas sob tração e impacto, contudo, as Tg s apresentaram uma queda de 30 % em relação ao epóxido. Ao contrário da moldagem por casting, no RTM a adição de MWCNT proporcionou aumentos significativos nas propriedades mecânicas analisadas.

Cement slurries are used in oil wells to isolate the production area from the rock formation. An important property of these materials is their durability. Due to the interactions of the cement slurries with aggressive media in the oil wells, the durability can be threatened or lost. Cement slurries modified with polymers are promising materials candidates for cementing oil wells. Thus, it is necessary to evaluate new materials in hostile environments. In this work, new cement slurries were prepared with the Epoxy resin and the ethylenediamine hardener in two different media: distilled water and sea water. The new slurries were tested for their mechanical properties and characterized before and after interaction with the following media: production water, hydrochloric acid solution and mud acid solution. After 365 days of contact with the production water, the modified slurries showed greater chemical and mechanical resistance compared to the slurries without the polymer network (Standard slurries). Moreover, for the modified slurries after contact with the production water, a decrease of 9% in the compressive strength occurred, whereas for the slurries without the polymer network, the reduction reached 40%. Kinetic studies, chemical and thermodynamic equilibrium were carried out in the investigation of the interaction of the cement slurries with the solutions of HCl and mud acid. The results have suggested that the interactions between the modified slurries and the acid media are due to surface reactions with preservation of the hydrated compounds of the cement, causing a mass loss around 25%. For the standard slurries, the mechanism is predominantly diffusion, with structural deterioration of these slurries and mass loss of approximately 46%. Thus, the modified slurries with the polymer network Epoxy-EDA presented good characteristics to be used in the oil well procedures. / Pastas de cimento são utilizadas em poços de petróleo para isolar a zona de produção da formação rochosa. Uma propriedade importante desses materiais é sua durabilidade. Devido suas interações com meios agressivos, essa propriedade pode ser ameaçada ou perdida. Pastas de cimento modificadas com polímeros são materiais promissores candidatos à cimentação de poços de petróleo. Assim, é necessário avaliar novos materiais em meios hostis. Neste trabalho, novas pastas de cimento foram preparadas com a resina Epoxy e o endurecedor Etilenodiamina em dois meios distintos: água destilada e água do mar. As novas pastas foram testadas em relação às suas propriedades mecânicas e caracterizadas antes e após a interação com os seguintes meios: água de produção, solução de ácido clorídrico e solução de mud acid. Após 365 dias de contato com a água de produção, as pastas modificadas apresentaram maior resistência química em comparação com as pastas sem a rede polimérica (pastas padrão). Além disso, para as pastas modificadas após o contato com a água de produção, ocorreu uma diminuição de 9% na resistência à compressão, já para as pastas sem a rede polimérica, a redução atingiu 40%. Estudos cinéticos, equilíbrio químico e termodinâmico foram realizados na investigação da interação das pastas de cimento com as soluções de HCl e mud acid. Os resultaram sugerem que as interações entre as pastas modificadas e os meios ácidos são devido a reações superficiais com preservação dos compostos hidratados do cimento, ocasionando uma perda de massa em torno de 25%. Para as pastas padrão, o mecanismo é predominantemente por difusão, com deterioração estrutural dessas pastas e perda de massa de aproximadamente de 46%. Desta forma, as pastas modificadas com a rede polimérica Epoxy-EDA apresentaram boas características para serem utilizadas em ambientes subterrâneos dos poços de petróleo. / São Cristóvão, SE

L’utilisation des matériaux composites devient de plus en plus importante dans les structures aéronautiques de nouvelle génération. Le gain de masse engendré, et donc de carburant, pousse les constructeurs aéronautiques à les employer de façon optimale. Néanmoins, ces matériaux se dégradent rapidement lorsqu’ils sont soumis à des flux de chaleur importants, entraînant une perte de leur résistance mécanique. Ce problème peut être dramatique pour la sécurité des passagers car la tenue de ces nouvelles structures peut ne plus être assurée dans le cas d’un incendie. Les méthodes actuelles de certification de la tenue au feu des matériaux composites aéronautiques reposent principalement sur l’utilisation de moyens expérimentaux, dont les résultats ne sont représentatifs que des conditions particulières dans lesquelles les essais ont été réalisés. La compréhension des différents phénomènes thermiques, chimiques et mécaniques intervenant lors de la dégradation de ces matériaux, avec l’appui de simulations numériques et d’expériences, peut permettre d’améliorer les méthodes existantes et donc d’optimiser les futures structures aéronautiques dès la phase de conception.Cette étude s’est attachée à développer et valider un modèle thermo-chimique de dégradation des matériaux composites multi-dimensionnel et multi-constituants. Ce modèle permet de traiter des cinétiques de dégradation complexes suivant plusieurs réactions de décompositions et de prendre en compte le transport des gaz produits depuis leur formation jusqu’à leur évacuation hors du matériau. L’utilisation de lois d’homogénéisation avancées est proposée afin de rendre compte des effets des transformations sur les transferts de chaleur et de masse se produisant au sein du matériau. L’application du modèle thermo-chimique à un cas de dégradation sous flux thermique connu mais non-uniforme dans un environnement contrôlé permet de confronter les résultats de simulation aux mesures expérimentales et ainsi de valider l’approche multi-constituants adoptée. Enfin, l’étude numérique de la dégradation d’un composite soumis à une flamme met en avant l’effet des gaz de décomposition éjectés à l’interface sur le flux thermique pariétal échangé. / Composite materials are increasingly used in new generation aircraft structures. Mass and as a consequence fuel savingsencourage aircraft manufacturers to use them optimally. However, these materials can degrade quickly when exposed tosignificant heat fluxes, resulting in a loss of mechanical strength. This problem can be dramatic for passenger safety asmechanical resistance of such innovative structures can not be ensured in case of fire events. Current certification methodsof fire resistance of aeronautical composite materials are mainly based on experiments, that are only representative of thespecific conditions under which they were carried out. The understanding of thermal, chemical and mechanical phenomenaoccurring during the decomposition of these materials, with the support of numerical simulations and experiments, can helpimproving existing methods and optimizing the future aeronautical structures from the design chain. This study deals withthe development and validation of a multi-components and multi-dimensional thermo-chemical model of decomposing compositematerials. It can deal with complex degradations following several decomposition reactions as well as transport ofpyrolysis gases from their formation up to their ejection out of the material. The use of advanced homogenization laws isproposed to account for the chemical transformations on heat and mass transfers occurring in the material. The applicationof the thermo-chemical model to a laser degradation study under known but non-uniform heat flux in a controlled environmentallows to confront the simulation results with experimental measurements and thus validate the multi-componentsapproach. Finally, the numerical analysis of a decomposing composite material submitted to a flame highlights the effectof emitted decomposition gases on the exchanged parietal heat flux.

La solution collage représente un intérêt industriel croissant dans l’assemblage des matériaux. Cependant, à cause des propriétés propres d’un polymère, l’utilisation de cette technologie d’assemblage est limitée par sa température de service. Afin d’augmenter la zone d’opérabilité du joint adhésif, la solution du Joint Multi Adhésifs a déjà été initiée par le passé. Ce joint repose sur la combinaison d’un adhésif résistant à basses températures LTA et d’un second résistant à hautes températures HTA. Le premier joint est placé sur les bords de l’assemblage tandis que le second occupe une position centrale. Partant du concept du Joint Multi Adhésif, l’objectif de ce travail est de proposer un assemblage à un seul joint dont les propriétés seraient modulées le long de la longueur de recouvrement. Ce nouvel adhésif présente une bonne résistance aux contraintes de pelage et de clivage sur les bords de l’assemblage, tout en assurant un rôle structurant à hautes températures. La formulation de cet adhésif consiste à élaborer un joint époxyde présentant une ténacité accrue à ces extrémités, qui diminue graduellement vers le centre de joint polymère. Outre leur capacité à augmenter considérablement la ténacité des thermodurcissables, les copolymères triblocs, de part la structuration à l’échelle nanoscopique qu’ils engendrent au sein ces matériaux, ont l’avantage de ne pas pénaliser les autres propriétés telles que le module d’Young et la température de transition vitreuse. Par ailleurs, grâce à leurs bonnes propriétés d’adhésion, les résines époxydes sont des polymères de choix dans l’élaboration d’adhésif. Par conséquent, tout l’intérêt de ce travail réside dans la synergie des propriétés de ces deux composants. Pour se faire, deux adhésifs époxydes sont formulés. Le premier est un système époxyde classique DER 332-MDEA. Le second est basé sur le même système DER 332-MDEA, mais il est chargé avec 10% en masse de copolymères type PMMA-b-PBA-b-PMMA. Les deux adhésifs massiques sont caractérisés thermiquement, thermomécaniquement et mécaniquement. En second lieu, afin de formuler le joint souhaité, à gradient de propriétés, une étude de la cinétique de diffusion entre les deux adhésifs est entreprise par un suivi rhéologique de l’évolution des modules. Cette étude permet de mettre en évidence les facteurs clefs qui pilotent la diffusion : la température, l’entrefer, la fraction initiale et la polarité du copolymère. Ce travail expérimental permet d’aboutir à l’établissement d’un modèle rhéologique mettant en lumière la compétition diffusion/confinement. L’impact de ce nouveau joint sur la propagation d’une fissure au sein d’un assemblage collé est évalué par un essai de clivage symétrique. / Adhesively bonding technology is of great industrial interest. However, the thermal limited properties of polymers used as adhesive joins limits the operating temperature. To extend the operating temperature range, the Multi Moduli Lap Joint solution has ever been suggested. This solution is an interface with a combination of a low-temperature adhesive LTA (i.e. strengthening for low temperatures) and a high-temperature adhesive HTA (i.e. strengthening for high temperatures), on three joints. Due to its position on each edge of the assembly, the ABT exhibits a great peeling yield, whereas the HTA presents a high shear strength and ensures a structural behaviour. This research aim consists in formulating a new simple lap joint with a gradient of mechanical properties along the bondline. The adhesive formulation has to exhibit a high toughness on its edges which gradually diminishes towards its center. So triblock copolymers are blend into an epoxy resin to obtain a nanostructured adhesive. Thus, a toughness improvement occurs with any depreciation neither of the Young modulus nor the transition glassy temperature. Moreover epoxy resin is well known for its bonding properties. Adhesives are formulated on the basis of the epoxy-amine system: DER 332-MDEA and a DER 332-MDEA nanostructured by 10%wt PMMA-b-PBA-b-PMMA triblock copolymers. First the neat and the nanoscopic-scale-structured thermosets are characterised by thermal, thermomechanical and mechanical tests. Then, to obtain a properties gradient into an adhesive joint, diffusion kinetics between both materials is monitored by rheometer. This study reveals the key parameters that master diffusion phenomenon such as temperature, gap, polarity and weight content of the triblock copolymers. This work allows establishing a rheological model which brings into focus competition between diffusion/wall phenomenon. The impact of this new joint on crack propagation is carried out by cleavage using the wedge test method.

The diploma thesis deals with the development of polymeric repair mortars in two qualitative levels ECONOMY and PREMIUM, designed especially for heavy engineering plants and the energy industry. In order to effectively withstand difficult industrial conditions, the developed materials should meet the highest requirements such as increased chemical and heat resistance, excellent adhesion to the concrete substrate, minimal shrinkage and other physical and mechanical properties. The PREMIUM level is aimed to achieve maximum physical and mechanical properties. Within the economy version, the emphasis is placed not only on very good properties, but also the possibility capability of reducing price of the resulting material. The partial aim of this work is the efficient use of secondary raw materials, mainly based on industrial waste in the form of fillers to the developed polymeric repair mortars.

New types of highly chemically resistant coating systems, primarily designed for concrete and metal substrates are designed and experimentally verified within the diploma thesis. Secondary raw materials, including solidified hazardous waste, are used as microfillers. The developed coating system is solved in two quality levels – PREMIUM and ECOLOGY. The level of PREMIUM is mainly designed for environments where extreme chemical stress is occurring. The polymer coating systém ECOLOGY can be used in environments where aggressive chemical media also act, however the ecological foot of the input raw materials is most important. The diploma thesis is dealing with current issues in the practice and it is the part of the research project.

The thesis deals with the pouring of epoxy materials over LED strips. The research part contains an introduction to photometry and summarizes the types of potting compounds along with their characteristics. The practical part delves into the effect different amount of pigment has on the photometric properties. This is assessed based on verified measurements performed with the help of a goniophotometer on samples with different amounts of pigment, which were created using an integration sphere. Furthermore, a brightness analysis and a long-term outdoor test were performed.

This work deals with influence nanoparticles, as fillers of polymer, to electrical properties dielectric composite materials. Addition of just a few weight percent of nonofillers has profound impact on the physical, chemical, mechanical and electrical properties orf polymer. Simultaneously is focused on production and diagnostics by the relaxation spectroscopy and measure internal resistance. Examination material is epoxy resin TSA 220S filled Al2O3 and SiO2 nanoparticles.

The diploma thesis deals with development of a new progressive anchor material on the polymer base. Nowadays, it is effort to utilize secondary raw materials in building industry as much as possible both from an environmental aspects in order to save primary energy sources and the reduction of waste and also due to economic reasons. Therefore, there is an effort to utilize high amount of suitable and appropriately treated secondary raw materials into the anchor materials. The main aim of this work is to develop high quality anchor material characterized by excellent ratio between speed and strength growth, high chemical resistance, thermal resistance and particularly minimal shrinkage. This new material is designed especially for anchoring building structures heavy machines steel barriers and other elements.

Zur Erfassung der mechanischen Eigenschaften im Grenzschichtbereich von Einzelfaser-Modellverbunden und deren Veränderung bei zyklischer Beanspruchung wurde ein elektronisches Mess- und Auswerteverfahren entwickelt. Der Hysteresemessplatz wird bezüglich der Messwerterfassung und Auswertung erweitert und dadurch dessen Messgenauigkeit und Anwendbarkeit verbessert. Im Vergleich zu den zyklischen Untersuchungen anhand des Hysteresemessverfahren (langsamer Einstufenversuch, dynamischer Einstufenversuch, Laststeigerungsversuch) wurden quasistatische Faserauszugtests (Pull-out) [76] durchgeführt. Durch kleine Amplituden von 3 – 4 µm findet die Messung im Bereich des linear-elastischen Materialverhaltens statt, wodurch die gemessenen Eigenschaften im Grenzschichtbereich von der Amplitude unabhängig sind. Kleine Schädigungen treten nur durch zyklische Beanspruchung auf. Somit können die Ermüdungseigenschaften des Einzelfaser-Modellverbundes im Grenzschichtbereich beobachtet werden. Die Einzelfaser-Modellverbunde wurden unter reproduzierbaren Bedingungen auf einer Fasereinbettanlage hergestellt. Der Einzelfaser-Modellverbund stellt eine Abstraktion der Komplexität des makroskopischen Verbundes dar. Dadurch ist eine selektive, lokale Aussage über die mikromechanischen Eigenschaften der Faser-Matrix-Grenzregion ermöglicht. Die in der Grenzschicht zwischen der Glasfaser und der Epoxidharzmatrix hervorgerufene Wechselwirkung wird durch die Oberflächenmodifizierung der Faser beeinflusst. Als Oberflächenmodifizierungen werden Aminopropyltriethoxysilan (APS) in Kombination mit Polyurethan (nicht kompatibel) sowie Epoxid-Filmbildner (kompatibel) betrachtet. Als Modellfälle kommen ungeschlichtete sowie mit Polyvinylacetat geschlichtete Glasfasern zur Anwendung. Als Modellmatrix wird ein reaktives Epoxidharz eingesetzt. Anhand verschiedener Faser-Matrix-Systeme kann festgestellt werden, dass der eingesetzte Haftvermittler eine gute Faser-Matrix-Haftung bewirken, wohingegen Filmbildner die Haftung verschlechtern, insbesondere wenn sie inkompatibel zur verwendeten Matrix sind. Durch unterschiedliche Oberflächenbehandlungen wird die Faser-Matrix-Haftung verändert, was auch zur Veränderung der Ermüdungseigenschaften während der zyklischen Belastung führt. Bei den APS-Proben mit Haftvermittler wurden sehr gute Haftung (hohe Werte für die Scheinbare Scherfestigkeit) zwischen der Glasfaser und der Matrix und gute Ermüdungseigenschaften (geringe Veränderung der Werte für scheinbare Scherfestigkeit, E-Modul etc.) erreicht. Bei den APS/EP-Proben wird durch den Zusatz von Filmbildnern die direkte Verbindung zwischen der Glasfaseroberfläche und der Matrix zum Teil abgeschwächt, was sich im Abfall sowohl der mechanischen Eigenschaften (Abfall de Werte für E-Modul, Steifigkeit etc.) als auch in schlechten Ermüdungseigenschaften widerspiegelt. Der Filmbildner auf Basis von Epoxidharz nimmt offensichtlich während des Herstellungsprozesses an der Vernetzung im Grenzschichtbereich teil und es erfolgt eine gute Interdiffusion der Schlichte in die Matrix. Dies führt dazu, dass APS/EP-Proben im Vergleich zu den APS/PU-Proben ein besseres Eigenschaftsbild aufweisen. APS/PU-Proben zeigen gegenüber ungeschlichteten Fasern eine etwas erhöhte Faser-Matrix-Haftung im Faserauszugstest, jedoch im dynamischen Einstufenversuch ist die Veränderung der Eigenschaften zwischen Anfang und Ende der Messung am größten. Bei der Deformation im Grenzschichtbereich ist bei dem Laststeigerungsversuch ein großer plastischer Anteil vorhanden, was dazu führt, dass das Versagen beim dynamischen Einstufenversuch nicht plötzlich auftritt. Es wird vermutet, dass beim Filmbildner auf Basis von Polyurethan nur eine geringe Interdiffusion in die Epoxidmatrix stattfindet. Bei den PVAc-Proben verleiht der PVAc-Filmbildner der Grenzschicht ebenfalls, trotz geringer Haftung zwischen Faser und Matrix, eine gewisse Plastizität und Fähigkeit, Energie zu dissipieren. Diese Eigenschaft der Schlichte kann auch bei den Laststeigerungsversuchen beobachtet werden. Die schwache Haftung führt jedoch beim Faserauszugtest zu kleinen scheinbaren Scherfestigkeiten. Ungeschlichtete Glasfasern bilden keine signifikante Faser-Matrix-Haftung, verbessert durch Wechselwirkung, aus, die der Dauerbelastung stand halten. Sehr kleine Werte für scheinbare Scherfestigkeiten im Faserauszugtest gehen konform mit einem spröden Versagen im Grenzschichtbereich, was sich in einem plötzlichen Abfall der Eigenschaften bei zyklischer Belastung bemerkbar macht. Im Vergleich zu den zyklischen Untersuchungen an Einzelfaser-Modellverbunden ergeben quasistatische Untersuchungen, bedingt durch die Signifikanz der Grenzschicht, gleiche Tendenzen. Eine gute Korrelation kann zu den Ergebnissen des statischen Querzugversuches an Unidirektionalverbunden festgestellt werden, da hier ebenfalls die Grenzschicht einen dominanten Einfluss ausübt. Die zyklische Wechselbelastung der unidirektionalen Zugprüfkörper reflektiert neben dem Grenzschichteinfluss sehr stark die Faserfestigkeit sowie Probleme des Lasteintrages, die nur bedingt mit einem Debonding sowie einem Scherversagen in der Grenzschicht verglichen werden kann. Bedingt durch unterschiedliche „Dehnbarkeit“ im Grenzschichtbereich (in der Grenzschicht) können Korrelationen zu den mikromechanischen Versuchsergebnissen bei zyklischer Wechselbelastung festgestellt werden. Zusammenfassend kann eingeschätzt werden, dass die hohe Empfindlichkeit des Hysteresemessverfahrens es ermöglicht, in kurzer Zeit den Einfluss verschiedener Oberflächenmodifizierungen zu beurteilen und damit eine Vorauswahl über die im Verbund gebildeten Grenzschichten zu treffen.