In landfill design, the containment of solid and liquid contaminant is essential. Leachate is produced from the biodegradation of the waste with the migration of liquid including rain-water through the heap. This liquid can become a health hazard if it leaches into the groundwater. Liners are placed beneath leachate collection systems to prevent leachate from seeping into the soil underneath the landfill. Compacted clay liners, usually containing bentonite clay, are widely used. Bentonite can be characterized by its low hydraulic conductivity and high swell potential. With a low hydraulic conductivity, the liner can serve as a barrier. The high swell potential aids in the integrity of a liner when suffering from cracking or puncturing. The chemicals that can be found in leachate are capable of increasing the clays hydraulic conductivity due to chemical interactions. Chemical compatibility testing - laboratory hydraulic conductivity tests using specific chemical solutions as a permeant - are performed to determine the effects. Laboratory hydraulic conductivity tests, regardless of the permeant, can be time-consuming and expensive. In this study, pure Wyoming bentonite clay and Bentofix clay were used. Deionized water and 0.01M, 0.1M, 0.5M concentrations of four inorganic salt (NaCl, KCl, MgCl2, and CaCl2) solutions were the liquids to which both clays were exposed during testing. Plastic limit and liquid limit tests were run on both clays with all 13 liquids. Laboratory hydraulic conductivity testing with pure Wyoming benonite clay was done with 12 different permeants- all solutions except 0.01M CaCl2 and 0.5M CaCl2. The hydraulic conductivity testing on Bentofix clay was run with 3 permeants- de-ionized water, 0.1M CaCl2, and 0.1M NaCl. The purpose of this study was to determine if a correlation exists between the experimentally determined liquid limit and plastic limit of a specific clay and its hydraulic conductivity when exposed to a synthetic leachate. It was determined that a trend exists that will allow for less expensive and time-consuming determination for hydraulic conductivity of a clay liner when exposed to a specific chemical solution. However, more experimental data need to be collected before a definite trend is verified. The proposed procedure requires that a hydraulic conductivity test of the clay be run using deionized water as the permeant, and plasticity index tests be performed using the leachate.

Este trabalho apresenta resultados de ensaios de fissuramento sob tensão (FST) realizados em geomembranas de polietileno (PE) virgens e degradadas em laboratório. As geomembranas foram degradadas pela exposição à radiação ultravioleta, por envelhecimento térmico em estufa com circulação de ar, e pela compatibilidade química com soda cáustica e com vinhaça. Os resultados destes ensaios demonstram que os processos de degradação a que as geomembranas foram submetidas podem ser considerados catalisadores do fenômeno de FST, pois ocorreram reduções de resistência ao FST da ordem de 50 a 60%, com exceção para a amostra em compatibilidade química com vinhaça, que obteve aumento de 17% na resistência ao FST / This work presents results of stress cracking tests (SC) accomplished in virgin and degraded polyethylene (PE) geomembranes at laboratory. Geomembranes were degraded by exposition to ultraviolet radiation, by thermal aging in oven with circulation of air, and by chemical compatibility with sodium hydroxide and with leachate of alcohol production. The results of these tests demonstrate that the degradation processes of the geomembranes were submitted can be considered catalysts of the phenomenon of SC, because they happened resistance reductions to stress crack resistance of the order from 50 to 60%, with exception for the sample in chemical compatibility with leachate of alcohol production, that had an increase of 17% in the stress crack resistance

Este trabalho apresenta resultados de ensaios de fissuramento sob tensão (FST) realizados em geomembranas de polietileno (PE) virgens e degradadas em laboratório. As geomembranas foram degradadas pela exposição à radiação ultravioleta, por envelhecimento térmico em estufa com circulação de ar, e pela compatibilidade química com soda cáustica e com vinhaça. Os resultados destes ensaios demonstram que os processos de degradação a que as geomembranas foram submetidas podem ser considerados catalisadores do fenômeno de FST, pois ocorreram reduções de resistência ao FST da ordem de 50 a 60%, com exceção para a amostra em compatibilidade química com vinhaça, que obteve aumento de 17% na resistência ao FST / This work presents results of stress cracking tests (SC) accomplished in virgin and degraded polyethylene (PE) geomembranes at laboratory. Geomembranes were degraded by exposition to ultraviolet radiation, by thermal aging in oven with circulation of air, and by chemical compatibility with sodium hydroxide and with leachate of alcohol production. The results of these tests demonstrate that the degradation processes of the geomembranes were submitted can be considered catalysts of the phenomenon of SC, because they happened resistance reductions to stress crack resistance of the order from 50 to 60%, with exception for the sample in chemical compatibility with leachate of alcohol production, that had an increase of 17% in the stress crack resistance

Le développement de structures de plus en plus légères et présentant des rapports performances/coût toujours plus élevés est un enjeu permanent dans le domaine des transports. Les matériaux polymères présentent des caractéristiques particulièrement bien adaptées à ces besoins. Ce travail de thèse repose sur le développement d’un matériau polymère destiné à être utilisé en tant que liner de réservoir de stockage d’oxygène liquide (LOX). L’objectif est de démontrer une réduction des masses de l’ordre de 20 à 30%, en comparaison avec des structures métalliques. Pour les besoins de l’application, le matériau à développer se doit de présenter une bonne compatibilité au LOX, une faible perméabilité aux gaz, des propriétés mécaniques suffisamment élevées à basse température ainsi qu’une bonne aptitude à la mise en forme par rotomoulage. La première partie de ces travaux a porté sur la compatibilité au LOX des polymères. En tenant compte des théories proposées dans la littérature, des nanocomposites à matrice polyamide 6 (PA6) ont été élaborés et caractérisés afin d’atteindre les performances recherchées. L’influence de différents paramètres supposés régir la tenue à l’oxygène liquide des matériaux polymères a ensuite été déterminée. Les nanocomposites obtenus présentent globalement une bonne compatibilité avec le LOX. Cette étude a également permis de mettre en évidence que les résultats sont fortement dépendants des paramètres liés à l’échantillonnage. Dans un second temps, la processabilité par rotomoulage de ces nanocomposites PA6 a été évaluée. Les propriétés rhéologiques et de stabilité thermique ont notamment été étudiées. Quelques essais de rotomoulage sur les systèmes les plus pertinents ont également été réalisés et ont démontré des résultats encourageants. Dans une dernière partie, les propriétés barrière aux gaz de ces systèmes PA6 ont été étudiées. Les perméabilités mesurées ont été interprétées en tenant compte de la morphologie des mélanges. En particulier, cette étude montre que les nanocomposites à base de PA6 et de graphite lamellaire présentent des performances adaptées pour l’application en raison de l’effet de tortuosité induit par la charge. Les propriétés mécaniques en traction uniaxiale des systèmes élaborés ont finalement été déterminées et confrontées aux spécifications requises. Les résultats obtenus montrent que les caractéristiques mécaniques sont tout à fait adaptées pour une utilisation en tant que liner de réservoir de stockage d’oxygène liquide. / In the field of transport, the development of lighter, cheaper and more efficient structures is a recurrent challenge. Polymer materials are good candidates for these applications due to their characteristics quite suitable for requirements. This Phd work aims at developing a thermoplastic material which will be used as an internal liner of a liquid oxygen (LOX) storage tank. The objective is to demonstrate a 20 % to 30 % weight saving, compared to metallic structures. To be used in this kind of application, the thermoplastic material must be LOX compatible, processable by rotational moulding and display a low gas permeability as well as good mechanical properties at low temperatures. In a first part, LOX compatibility of polymers was studied. Taking into account theories proposed in the literature, polyamide 6 (PA6) nanocomposites based on LCP, fluoride and graphite fillers were processed and characterized in order to reach desired properties. The influence of several parameters having an impact on LOX behaviour of polymers was then investigated. The nanocomposites show overall good compatibility with liquid oxygen. This study also demonstrates that LOX sensitivity largely depends on the preparation of samples. The processability of nanocomposites by rotational moulding has then been investigated. Rheological properties and thermal stability have especially been studied. Some rotational moulding trials were carried out on the most relevant systems and demonstrate promising results. Finally, the gas transport properties of PA6 nanocomposites were studied. Measured gas permeability was discussed as a function of the morphology of blends. In particular, this study shows that PA6 nanocomposites filled with lamellar graphite present convenient performances which are due to the tortuosity effect induced by the filler. Mechanical properties of filled systems were finally determined and compared with set requirements. The results show that mechanical characteristics are quite relevant for use as internal liner of LOX storage tank.

Работа содержит 71 страницу, 52 рисунка, 8 таблиц, 73 наименования в списке литературы. Ключевые слова: ТВЕРДООКСИДНЫЙ ТОПЛИВНЫЙ ЭЛЕМЕНТ, КАТОДНЫЙ МАТЕРИАЛ, СТРУКТУРА РАДДЛЕСДЕНА-ПОППЕРА, ТЕРМИЧЕСКОЕ РАСШИРЕНИЕ, ЭЛЕКТРОПРОВОДНОСТЬ, ХИМИЧЕСКАЯ СОВМЕСТИМОСТЬ. Методом пиролиза глицерин-нитратных композиций проведен синтез сложных оксидов Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.4). Методом рентгеновской дифракции определен фазовый состав порошков Nd1.6Ca0.4Ni1 yCuyO4+δ (y = 0.0-0.4) (ДРОН-6). Методом Ритвелда при использовании программного пакета FullProf Suite уточнены кристаллоструктурные параметры Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.3) при 25 С. Проведены высокотемпературные рентгеновские исследования порошков Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0 - 0.3). Методами термогравиметрии (NETZSCH STA 449F3) и окислительно-восстановительного (потенциометрического) титрования (Аквилон АТП-02) проведено определение абсолютного содержания кислорода в образцах Nd1.6Ca0.4Ni1 yCuyO4+δ (y = 0.0-0.3) на воздухе. Методом дилатометрии (Netzsch DIL 402C) исследовано термическое расширение спеченных образцов Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.3). Из наклона экспериментальных зависимостей относительного удлинения образцов рассчитаны изобарические линейные коэффициенты термического расширения Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.3). Четырех-зондовым методом на постоянном токе на воздухе с использованием автоматической системы Zirconia-318 получены температурные зависимости проводимости спеченных образцов Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.3). Проведены исследования химической совместимости Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0; 0.2; 0.4) с оксидными материалами для традиционных электролитов ТОТЭ. На анализаторе дисперсности SALD-7101 Shimadzu методом лазерного светорассеяния выполнено определение распределения частиц по размерам в порошках Nd1.6Cа0.4Ni1-yCuyO4+δ (y = 0.0-0.4). Величины удельной поверхности Nd1.6Cа0.4Ni1-yCuyO4+δ (y = 0.0-0.4) оценивали методом тепловой десорбции азота на автоматическом анализаторе поверхности и пористости SoftSorbi-II ver.1.0. Определение коэффициента диффузии ионов кислорода проводили методом температурно-программируемого изотопного обмена. Электрохимическая активность катодных материалов Nd1.6Cа0.4Ni1-yCuyO4+δ (y = 0.0; 0.1; 0.3) исследована методом импедансной спектроскопии с помощью потенциостата SI 1260 и электрохимического интерфейса SI 1287 (Solartron Industries Inc.). На основе полученных данных сделан вывод о перспективности оксидных материалов Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0 0.4) в качестве катодных материалов для среднетемпературных ТОТЭ. / Present work contains 71 pages, 52 figures, 8 tables, 73 references in the literature list. Keywords: SOLID OXIDE FUEL CELLS, CATHODE, RUDDLESDEN-POPPER STRUCTURE, THERMAL EXPANSION, ELECTROCONDUCTIVITY, CHEMICAL COMPATIBILITY. Synthesis of the Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.4) complex oxides was carried out by the glycerol-nitrate compositions pyrolysis. Phase composition of the Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.4) powders was determined by the X-ray diffraction (DRON-6). The crystal structure parameters of the Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.4) oxides at 25 °C were refined by the Rietveld method using the FullProf Suite software package. High-temperature X-ray studies were performed on the Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.3) powders. The thermogravimetry (NETZSCH STA 449F3) and redox titration (potentiometric) methods (Aquilon ATP-02) were used for the determination of an absolute oxygen content in the Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.4) samples in air. Thermal expansion of the compact Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.4) samples were studied using the dilatometry (Netzsch DIL 402C) method. The isobaric linear coefficients of the Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.4) thermal expansion were calculated from linearization of the experimental dependencies of samples’ relative elongation. The temperature dependencies of the Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.4) compact samples’ conductivity were obtained using the four-probe method at direct current in air with automatic system Zirconia-318. Chemical compatibility of the Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0; 0.2; 0.4) with electrolytes oxide materials for solid oxide fuel cells (SOFC) has been studied. Particle size distribution in the Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.4) powders was determined by laser light scattering using a SALD-7101 Shimadzu dispersion analyzer. The values of the Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.4) specific surface were estimated by the method of nitrogen thermal desorption on an automatic surface and porosity analyzer SoftSorbi-II ver.1.0. The oxygen ion diffusion coefficients were determined by temperature programmed isotope exchange of oxygen. Electrochemical activity of the Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0-0.4) cathode materials was investigated by impedance spectroscopy using a SI 1260 potentiostat and SI 1287 electrochemical interface (Solartron Industries Inc.). Based on the obtained data, it could be concluded that the Nd1.6Ca0.4Ni1-yCuyO4+δ oxide materials are promising as cathode materials for intermediate-temperature SOFC’s.