Considerando a necessidade de adaptar, para mão de obra local e não especializada, os dos ciclos de desenvolvimento de projeto baseado em desempenho do material, objetiva-se comparar processos de projeto de modelos form-making, algorítmico e formfinding, e assim avaliar seus desempenhos estruturais; produzir um material compósito polimérico com fibra natural e, por último, generalizar um ciclo de desenvolvimento de projeto que englobe fabricação com materiais compósitos de morfologias oriundas de processos digitais de projeto. Deste modo, a hipótese avaliada pela tese, e que trata tanto as discussões sobre processo de projeto bem como a adaptação da fabricação para a mão de obra local é: o processo digital performático deve definir o material, além de aferir seu desempenho, já nas fases iniciais do ciclo de desenvolvimento do projeto. Para tanto, procede-se à uma abordagem de pesquisa orientada por projeto conhecida como design research, além metodologia exploratória, experimental, descritiva e de aplicação. Desse modo observou-se que os modelos de formação baseada em desempenho simulados apresentaram resultados menores na deformação máxima e energia elástica de deformação que resultam em estruturas otimizadas que necessitam de menos material para serem produzidas. Isto permitiu concluir que o ciclo de desenvolvimento de projeto proposto pela pesquisa é capaz de viabilizar formas não convencionais geradas por processos digitais de projeto e fabricadas com materiais compósitos poliméricos. / Considering the need to adapt, for local and non-specialized hand labor, the design development cycle based on material performance, this thesis aims to compare design methods through form-making, algorithmic and form-finding models, and thus to evaluate their structural performances; to produce a polymeric composite material with natural fiber and; at last, to generalize a design development cycle that encompasses fabrication with composite materials of morphologies originated by digital design. Thus, the hypothesis evaluated by this thesis, which addresses both the discussions about the design process as well as the adaptation of the manufacturing to the local workforce, is: the digital performative design must define the material, as well as measure its performance, already in the early stages of the design development cycle. In this sense, the study relied on a design driven research approach, known as design research, in addition to an exploratory, application, descriptive and experimental methodology. In this way, it was observed that, the simulated performance-based models presented lower results in the maximum deformation and elastic energy of deformation that resulted in optimized structures that requires less material to be produced. This allowed to conclude, that the design development cycle proposed by this research is capable of enabling non-conventional forms generated by digital design and fabricated with polymer composites.

Les matériaux composites, et en particulier les sandwichs, sont très étudiés depuis des décennies. En effet, l'alliance entre légèreté et résistance de ces structures entraîne le développement de leur utilisation. Leur méthode de fabrication et éventuellement leur caractérisation restent des points essentiels dans la plupart des études. Ce travail s’inscrit dans le projet FUI SOLLICITERN qui vise à développer une citerne routière en matériau composite sandwich pour un véhicule d’hydrocurage. Comme première étape, et à partir du principe de l’enroulement filamentaire classique, l’objectif consiste à chercher des conceptions qui sont les mieux adaptées à l’enroulement d’un matériau sandwich sur un mandrin cylindrique, tout en respectant les paramètres de l’enroulement et leur influence sur la structure et les propriétés. La solution optimale étant validée, les matériaux constitutifs ont été étudié en mesurant de nombreuses propriétés mécaniques. L’objectif est de pouvoir aider le bureau d’étude à valider une solution de fabrication et de vérifier que les propriétés sont celles attendues. Pour ce faire, des caractérisations statique et dynamique ont menée sur des échantillons incurvés fabriqués par le procédé optimisé pour notre application. Cette partie comporte notamment différents essais expérimentaux dans le but de valider le comportement de la structure visée avec les dimensions et les combinaisons de matériaux les plus appropriées, en tenant compte du processus de fabrication. La meilleure configuration structurelle est retenue à la fin pour la fabrication de la citerne routière prototype. / Composite materials, and especially sandwich structures, have been studied for decades. Indeed, the association between lightness and resistance of these structures leads to the development of their use. Their manufacturing method and their characterization remain as essential points in most studies. This work is part of the FUI SOLLICITERN project, which aims to design a composite water treatment tank for vehicles intended for this purpose. As a first step, and based on the classical filament winding principal, we aim to search designs that are best adapted to the fabrication of a curved sandwich material on a cylindrical mandrel, while respecting the process parameters of and their influence on structural properties. Since an optimal solution was validated, the constituent materials were studied by measuring mechanical properties. The objective is to help our industrial partner to validate a manufacturing solution and verify that such properties are the expected ones. For that, several static and dynamic characterizations were carried out on curved samples manufactured by the optimized process designed for our application. This part includes various experimental tests in order to validate the structure behavior with the most appropriate dimensions and material combinations, taking into account the manufacturing process. At the end, the best structural configuration is retained for the first tank prototype fabrication.

Le renfort des matériaux composites via la croissance de nanotubes de carbone (NTC) directement à la surface des renforts textiles permet d'augmenter certaines propriétés des composites. La méthode flamme est la technique facilement industrialisable à la continue qui permet de réaliser la croissance des NTC sur des textiles. Cependant un procédé à la continue va engendrer des contraintes sur les renforts, ainsi le but de ces travaux de doctorat est de déterminer le comportement des textiles après la croissance de NTC, sous différentes contraintes de type industrielles, et d'évaluer leur influence sur la mise en œuvre et les propriétés des matériaux composites. Ces travaux ont mis en évidence la formation d'un film de transfert dès le début du frottement de surfaces textiles recouvertes de NTC contre une pièce métallique ou un autre textile de même nature. De plus, la présence des NTC a permis de mettre en évidence un comportement spécifique en indentation. La mouillabilité des surfaces avec une résine époxy n'est en revanche pas influencée par la présence des NTC, si ce n'est que très faiblement dans la dynamique du mouillage. Il a été montré que les conditions de croissance des NTC, notamment la nature du catalyseur, avaient une influence sur la résistance à long terme du film de transfert formé après frottement, sur l'adhésion des NTC sur les fibres de renfort, ainsi que sur la dynamique du mouillage avec de la résine époxy. Finalement, des matériaux composites ont été fabriqués avec des renforts avant et après usure de la surface présentant des NTC, dans le but d'étudier son influence sur les propriétés des composites. L'usure, se traduisant par la transformation des NTC en film de transfert, n'influence ni les propriétés électriques des matériaux, ni les propriétés mécaniques en flexion 3 points. / Reinforcement of composite materials with carbon nanotubes (CNTs) grafted on textiles provides an increase in the properties of the composites. The flame method is the most rapid and the easiest industrialized technique to realize the growth of CNTs on textile surfaces. At an industrial scale, some strains will be applied between the CNTs’ growth step and the composite processing, which can cause damage on the CNTs and alter the positive contribution of the CNTs to the properties of composites. That is why the aim of this study is to determine the effect of different industrial stresses on the CNTs behaviour and their influence on the composite processing and composite properties. In this work, we highlighted the formation of a transfer film, composed of CNTs, during the friction of the CNTs against metallic pieces or against the same fabric. The presence of the CNTs shows a particular behaviour in indentation. However, the wettability with an epoxy resin is not influenced by the CNTs, except a little in the dynamic of the wettability. It has been shown that the growth condition of the CNTs, particularly the catalyst, has an influence on the long term resistivity of the transfer film formed by the friction, on the adhesion of the CNTs on the fibres and on the dynamic of the wettability with an epoxy resin. Finally, composite materials composed of CNTs growth fabrics before and after the wear of the surface, were manufactured in order to study the influence of the wear on the properties of the composite material. It appears that, the wear, causing the formation of the transfer film, has no influence on the electrical and flexural properties of the composite material.

Les propriétés thermomécaniques étonnantes des alliages à mémoire de forme (AMF) sont mises à profit dans de nombreux domaines. Ce matériau est capable de mettre en mouvement une structure suite à un changement de température. Or les façades de bâtiments contemporains, pour s’adapter à des conditions climatiques variables, doivent réguler le passage de la lumière et de l’énergie thermique, par exemple au moyen de systèmes motorisés. Le potentiel de fils AMF pour l’actionnement de protections solaires en façade est exploré ici. La modélisation du couplage mécanique induit par l’introduction de tels matériaux dans une structure a été peu étudiée : l’AMF agit sur la structure qui en retour modifie le comportement de l’AMF. La première étape de ce travail a consisté en une contribution à la modélisation du comportement thermomécanique de ce matériau reposant sur le choix d’une énergie libre, d’un potentiel de dissipation et de plusieurs variables internes. Deux modèles unidimensionnels ont été proposés : un premier modèle monocristallin reproduit de façon simplifiée le comportement du matériau, et un second modèle polycristallin propose une description plus fidèle. En parallèle un dispositif d’essai original à température contrôlée a été développé, il a permis une caractérisation fiable de fils Nickel-Titane et l’identification des paramètres des modèles. Dans un second temps ces modèles ont permis de résoudre des cas de couplage élémentaires (fil AMF + ressort, lame élastique + fil AMF noyé) pour des chargements thermomécaniques simples, et des solutions analytiques ont été établies. Les modèles ont été implémentés numériquement via un script matériau utilisateur (UMAT) pour le logiciel éléments finis ABAQUS et au moyen d’un algorithme d’optimisation sous contraintes. Ceci permet de simuler la réponse couplée de systèmes structuraux a priori quelconques intégrant des AMF, connectés à ou noyés dans, une structure. Dans un troisième temps, divers actionneurs ont été conçus, réalisés et testés dans le cadre de l’occultation solaire des façades. Le principe est d’utiliser un cycle de température permettant à l’AMF de déformer la structure, puis à l’énergie élastique de déformation de la structure d’assurer le retour à la forme originale. Le comportement réel de ces actionneurs a été comparé aux calculs analytiques et éléments finis. Des tests cycliques ont également été réalisés / The surprising thermomechanical properties of shape memory alloys (SMA) are harnessed in many engineering fields. This material is able to set a structure in motion upon a temperature change. Today, contemporary building facades must adapt to variable climate conditions as well as to evolving building use and occupancy. In particular, they must regulate light and thermal energy passing through the facade, with motorized systems, for example. We explore the potential of SMA wires for putting in motion solar shading devices in facades. The modelling of the mechanical coupling induced by the introduction of such materials in a structure has received little attention as of now. The SMA acts on the structure which in return modifies the SMA behavior. The first step of this work is a contribution to modelling the thermomechanical behavior of this material through the choice of a free energy, a dissipation potential and internal variables. We propose two one-dimensional models: a first monocrystalline model reproduces the material behavior in a simplified way, and a second polycrystalline model offers a more accurate description of it. An original temperature-controlled testing apparatus was developed in parallel. This led to a reliable characterization of Nickel-Titanium wires and the identification of the model parameters. In a second stage, these models allowed to solve elementary coupling cases (SMA wire + Spring, Elastic plate + Embedded SMA wire) for simple thermomechanical loadings and we established analytical solutions. The models were then numerically implemented via a user-material script (UMAT) for the finite elements software ABAQUS, by using a constrained optimization algorithm. This enables the simulation of the coupled response of, in principle, any structural system including SMA wires, connected or embedded in the structure. Finally, we designed, fabricated and tested different actuators in the context of sunlight control in facades. The working principle lies in using a temperature cycle which allows the SMA to deform the structure, and then allows the elastic strain energy in the structure to ensure the return to the original shape. The real behavior of these actuators have been compared to analytical and finite element calculations. We also performed cyclic tests

Ce travail est consacré à la description macroscopique de deux types de plaques structurées contrastées dont le comportement dynamique est atypique : le premier cas correspond à une plaque raidie dans une direction par des raidisseurs régulièrement espacés, le second correspond au cas d’une plaque bi-raidie dans les deux directions par un treillis périodique de poutres. Les différents régimes de comportement sont spécifiés en fonction des paramètres mécaniques et géométriques des raidisseurs et de la plaque. Le comportement dynamique de ces plaques est établi en faisant émerger, par homogénéisation asymptotique, la description locale et globale. Le modèle est construit à partir des équations élasto-dynamiques tri-dimensionnelles du matériau combinées à des développements asymptotiques. Le travail se concentre sur des situations de résonance interne qui correspondent à des contrastes spécifiques entre les paramètres de la plaque et du raidisseur. L’analyse met clairement en évidence les cinématiques enrichies de la plaque et aboutit à un modèle analytique macroscopique qui inclut les mécanismes de torsion et de flexion. Dans le cas de la plaque mono-raidie, un modèle hybride fait intervenir des paramètres effectifs dont les expressions analytiques sont précisées. Ce modèle est analogue à un modèle de poutre et permet d’appréhender le comportement de la plaque en incluant la résonance interne. Ce modèle non conventionnel montre la coexistence de deux régimes dynamiques. Les caractéristiques de dispersion atypique associées aux ondes de flexion et de torsion proviennent de paramètres effectifs dépendants de la fréquence, comme la masse effective, l’inertie de rotation effective, et la rigidité de torsion effective associées à la plaque. Cette théorie est ensuite étendue au cas de la plaque bi-raidie, et conduit à un opérateur de type plaque non conventionnel incluant des paramètres effectifs. Ces résultats permettent d’examiner des courbes de dispersion atypiques en fonction des contrastes géométriques et mécaniques entre les différents composants. La validité des modèles et leur robustesse sont vérifiées en comparant les résultats analytiques à des simulations numériques de type éléments finis WFEM. Les comparaisons montrent que les mécanismes observables numériquement sont bien décrits par le modèle analytique proposé. Enfin, deux maquettes sont utilisées pour la validation expérimentale : une correspondant à une plaque mono-raidie comportant un contraste géométrique, et l’autre correspondant à la plaque bi-raidie impliquant des contrastes géométrique et mécanique. Les réponses mesurées par vibromètre laser sont traitées par corrélation d’onde IWC. Les mesures sont reproduites pour plusieurs conditions limites de plaques internes et différentes valeurs de masse ajoutées pour montrer la performance du modèle homogénéisé. Une très bonne corrélation apparaît entre les mesures expérimentales et les prédictions issues du modèle. Cette approche peut être utilisée pour décrire le comportement de panneaux raidis industriels et pour concevoir des structures ayant des propriétés spécifiques à certaines fréquences. / This work is devoted to the modeling of two types of contrasted structured plates that exhibit non-conventional dynamic behavior : the first one corresponds to periodic unidirectionally stiffened plates and the second one corresponds to orthogonally stiffened plates. The different regimes of behavior are specified, according to the mechanical and geometrical parameters of the beam and the plate. The dynamic behavior of such stiffened plates is established by up-scaling, through multi-scale asymptotic method, the linear local description of the plate and the stiffening beams coupled together. The behavior is derived from the three-dimensional elastodynamic laws of the materials combined with asymptotic expansions formulation. The study focuses on situations of inner resonance that corresponds to specific mechanical contrasts between the beam and plate parameters. The analysis clearly evidences the enriched kinematics of such plate and yields to a synthetic and analytic macroscopic representation that encompasses the flexural and torsional mechanisms, as well as guided waves. In the case of unidirectionally ribbed plates, an effective hybrid beam/plate model is obtained and the analytical expressions of effective parameters are specified. It results in a beam-like operator that provides a simple understanding of the behavior taking into account inner resonance. This atypical model accounts from the coexistence of two types of dynamic regimes. The unusual dispersion features of flexural and torsional waves arise from frequency dependent parameters, namely, the effective mass, the effective rotational inertia and the effective torsional spring rigidity associated with the plate. The theory is then extended to an orthogonally ribbed plate, and yields a non-conventional plate model with frequency dependent parameters. These results allow investigating the atypical dispersion equation with respect to the geometrical and mechanical contrasts of the structural components. The validity and robustness of the model are also verified by comparing theoretical predictions with finite element based computations, namely the WFEM (Wave Finite Element Method). Comparisons show that mechanisms identified numerically are correctly predicted by the proposed homogenized model. Finally, two mock-ups are considered experimentally, corresponding to uni-directionally ribbed plate with geometrical contrast and orthogonally ribbed plates involving geometrical and mechanical contrasts. The out-of-plane displacement field under random excitation is measured using a scanning laser vibrometer, then post-processed using the IWC (Inhomogeneous Wave Correlation) method. This is performed for various internal boundary conditions and added mass to highlight the ability of the homogenized model to describe different configurations. A good agreement is found between the experimental measurements and the analytical predictions. The presented approach can be used to describe the motion of ribbed panels of industrial interest and/or to design structures having specific atypical features in a given frequency range.

A resistência à ruptura de materiais frágeis como o concreto de granulometria fina é fortemente dependente de sua heterogeneidade, do tamanho da amostra e da heterogeneidade das tensões. A partir de uma abordagem probabilista, fundamentada no modelo de Weibull, este trabalho trata da influência de tais efeitos sobre a resistência à tração de painéis compósitos formados por concreto de granulometria fina e telas soldadas. Desde que as armaduras se mantenham em regime elástico, mostra-se que o modelo de Weibull de dois parâmetros pode ser empregado com sucesso na previsão da ruptura dos painéis compósitos em estudo. Os parâmetros foram então identificados com medidas de ensaios de flexão em três e em quatro pontos de barras de concreto de granulometria fina de dois tamanhos diferentes. A utilização do modelo de Weibull confirmou, por outro lado, a validade da teoria de misturas como ferramenta para estimar as resistências de rupturas locais correspondentes a diferentes níveis de formação de fissuras / The rupture strength of brittle materials such as the microconcrete is strongly dependent on the microstructural heterogeneity, the sample size and the stress heterogeneity. Using a probabilistic approach, based on the Weibull distribution, this work deals with the influence of such effects on the tensile strength of composite panels formed by microconcrete and welded wire grids. Provide the reinforcements behaves in elastic regime, it is shown that the model of Weibull of two parameters can be used with success to predict the failure of the composite panels studied. The parameters were then identified from measurements of flexural tests in three and in four points of two different sizes of microconcrete samples. The feasibility of the Weibull model validates, as well, the rule of mixture as a satisfactory tool to estimate local failure strengths of related to different levels of cracking

Recent improvements in manufacturing processes and materials properties associated with excellent mechanical characteristics and low weight have became composite materials very attractive for application on civil aircraft structures. However, even new designs are still very conservative, because the composite structure failure phenomena are very complex. Several failure criteria and theories have been developed to describe the damage process and how it evolves, but the solution of the problem is still open. Moreover, modern manufacturing processes, e.g. filament winding, have been used to produce a wide variety of structural shapes. Therefore, this work presents the development of a damage model and its application to simulate the progressive failure of flat composite laminates as well as for composite cylinders made by filament winding process. The proposed damage model has been implemented as a UMAT (User Material Subroutine) and VUMAT (User Material Subroutine for explicit simulations), which were linked to ABAQUSTM Finite Element (FE) commercial package. Progressive failure analyses have been carried out using FE Method in order to simulate the failure of filament wound composite structures under different quasi-static and impact loading conditions. In addition, experiments have been performed not only to identify parameters related to the material model but also to evaluate both the potentialities and the limitations of the proposed model. / As recentes melhorias nos processos de fabricação e nas propriedades dos materiais associadas a excelentes características mecânicas e baixo peso tornam os materiais compósitos muito atrativos para aplicação em estruturas aeronáuticas. No entanto, mesmo novos projetos, ainda são muito conservadores, pois os fenômenos de falha dos compósitos são muito complexos. Vários critérios e teorias de falha têm sido desenvolvidos para descrever o processo de dano e sua evolução, mas a solução do problema ainda está em aberto. Além disso, técnicas modernas de fabricação, como o enrolamento filamentar (filament winding) vêm sendo utilizadas para produzir uma ampla variedade de formas estruturais. Assim, este trabalho apresenta o desenvolvimento de um modelo de dano e a sua aplicação para simular a falha progressiva de estruturas planas e cilíndricas fabricadas em material compósito através do processo de filament winding. O modelo de dano proposto foi implementado como sub-rotinas em linguagem FORTRAN (UMAT-User Material Subroutine e, VUMAT-User Material Subroutine para simulações explícitas), que foram compiladas junto ao programa comercial de Elementos Finitos ABAQUSTM. Várias análises numéricas foram realizadas via elementos finitos, a fim de prever a falha dessas estruturas de material compósito sob diferentes condições de carregamentos quase-estáticos e de impacto. Além disso, vários ensaios experimentais foram realizados, a fim de identificar os parâmetros relacionados com o modelo de material, bem como avaliar as potencialidades e as limitações do modelo proposto.

Die Entwicklung neuartiger transparenter Materialien durch Kombination von organischen Polymeren und anorganischen Füllstoffen wurde untersucht. Für die Synthese der nanoskopischen anorganischen Füllstoffe wurde der Sol-Gel-Prozess für Metallfluoride mit Magnesium angewandt und auf Zirkonium und Titan erweitert. Auch wurden neue Herstellungs- und Trocknungsmethoden für die daraus gewonnenen Xerogele variiert und optimiert. Die Charakterisierung der hergestellten Metallfluorid-Sole und daraus gewonnener Nanopartikel erfolgte mittels NMR- und IR-Spektroskopie sowie SAXS- und TEM-Messungen und Elementaranalysen. Zur homogenen Mischbarkeit von anorganischen Füllstoffen und organischer Polymermatrix sind Modifikationen der Partikeloberfläche notwendig. Diese erfolgten über kovalent gebundene, teilweise perfluorierte, Carbonsäuren. Der Fortschritt der Modifizierung sowie die Eigenschaften der erhaltenen modifizierten Nanopartikel wurden mittels NMR- und IR Spektroskopie, teilweise auch mittels TA, untersucht. Unter Verwendung verschiedener transparenter und industriell relevanter Polymermatrices konnten durch homogene Verteilung der Nanopartikel transparente Kompositmaterialien erhalten werden. Die Veränderung der mechanischen und thermischen Eigenschaften der einzelnen neuen Materialien im Vergleich zu den reinen Polymeren wurde mittels DSC, Zugversuchen und Nanoindentation bestimmt. Zusätzlich zu diesen Anwendungsbereichen wurde der Einsatz der Nanopartikel in Elektrodenmaterialien zur Steigerung der Lebensdauer von Akkumulatoren und daraus resultierender Leistungsverbesserung untersucht. / The development of new transparent materials by combination of organic polymers and inorganic fillers was investigated. The fluorolytic sol-gel process was used to prepare fluorine containing nanoscopic inorganic fillers with magnesium, zirconium and titanium as metal components. The preparation and drying methods for the synthesis of xerogels was varied and optimized. Characterization of the metal fluoride sols and the nanoparticles obtained from the sols was executed by NMR and IR spectroscopy as well as SAXS and TEM measurements and elemental analysis. To achieve homogeneous miscibility for the inorganic fillers with the organic polymer matrix modification of the particles’ surface is crucial. This was achieved by covalent attachment of carbon acids; in case of fluorine polymers perfluorinated carbon acids were used. The progress of surface modification and the properties of the modified nanoparticles were monitored by NMR and IR spectroscopy. Based on thermal analysis, thermal stability of the modified nanoparticles was investigated. The modified metal fluoride nanoparticles were introduced into transparent and for industrial applications relevant polymer matrices. A homogeneous distribution to transparent nano composite materials was observed. The alteration of mechanical and thermal properties of the new materials was investigated by DSC, tension tests and nanoindentation and compared with the unmodified pure polymers. Another field of application of these nanoparticles is their application on electrode materials with the aim to improve electrode lifetime and to achieve a better performance of rechargeable batteries.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Materiais mesoporosos ordenados tipo SBA-15 possuem uma rede de canais e poros de tamanho bem definido na escala nanométrica. Essa arquitetura particular de poros torna esses materiais viáveis para encapsular uma variedade de compostos na matriz da sílica, resultando em um material promissor para uma gama de aplicações. Esses materiais, quando contêm óxidos de metais de transição, especialmente nanopartículas de óxido de ferro magnéticas, podem ser usados para algumas aplicações in vivo, tais como no aumento do contraste em imagens por ressonância magnética nuclear, reparo de tecidos, imunoensaio, hypertermia, e liberação de fármacos. Nesse trabalho, nanopartículas magnéticas encapsuladas em sílica mesoporosa foram preparados em duas etapas. Primeiro a magnetita foi sintetizada pelo método de oxidação-precipitação a partir de uma solução de sulfato de ferro, hidróxido de potássio e nitrato de potássio. Em seguida, as nanopartículas magnéticas foram revestidas com sílica mesoporosa pelo uso de um surfactante não-iônico copolímero em blocos como agente direcionador da estrutura. A caracterização dos materiais foi feita por difração de raios X, adsorção de gases, infravermelho, espectroscopia Mössbauer, espectrometria de energia dispersiva (EDS), microscopia eletrônica de varredura (MEV), microscopia eletrônica de transmissão (TEM), espectroscopia de fotoelétrons excitados por raios X (XPS) e medidas magnéticas. Os resultados revelaram uma estrutura bem ordenada de mesoporos do nanocompósito, sugerindo que a mesma pode ser descrita como mesoporos hexagonais separados por uma parede de sílica contínua, formando uma camada de revestimento sobre as nanopartículas magnéticas. Dos dados de difração de raios X, foi obtido o tamanho médio das partículas de magnetita, que foi de 38 nm. A espectroscpia Mössbauer mostrou que a magnetita é preservada na rota de síntese. Os dados de XPS aliados aos de TEM mostraram que a rede de sílica recobre as partículas de magnetita, formando um nanocompósito com tamanho médio de grãos de 138 nm. Por fim, foi feito o estudo da influência dessas partículas magnéticas na cinética de liberação de três fármacos-modelo: cisplatina, carboplatina e atenolol sob condições in vitro. A liberação foi estudada na ausência e na presença de um campo magnético externo, utilizando para tanto um magneto NdFeB de 0,25 T. A análise foi feita por estudos de mecanismos cinéticos e de modelos de difusão, revelando que o campo externo influencia pouco no processo de liberação dos fármacos. Ao considerar que as nanopartículas estão presas na estrutura, esse resultado é coerente. Então, foi feito um teste para verificar a influência de um campo alternado no perfil de liberação, que mostrou um resultado mais significativo para a liberação de cisplatina. Para explicar esse fato, foi proposto então um modelo de interação entre a mesma e o nanocompósito. / Ordered mesoporous materials like SBA-15 posses a network of channels and pores of well-defined size in the nanoscale range. This particular pore architecture makes them suitable for hosting a broad variety of compounds into the silica matrix, resulting in very promising material for a broad range of applications, including magnetic carriers for drug delivery. In this work, magnetic nanocomposites embedded into mesoporous silica were prepared in two steps. Firstly, magnetite was synthesized by oxidation-precipitation method from a solution of iron sulfate, potassium nitrate and potassium hydroxide. After this, the magnetic nanoparticles were coated with mesoporous silica by using nonionic block copolymer surfactants as structure-directing agents. Characterization of the materials was carried out by using X-ray diffraction (XRD), 57Fe Mössbauer spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), N2 adsorption, energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), XRay Photoeletron Spectroscopy (XPS) and magnetic measures. Our results revealed a wellordered mesopore structure of the nanocomposite, suggesting that the samples structure can be described as a honeycomb of hexagonal mesopores separated by continuous silica walls and the coating layer is distributed over the magnetic nanoparticles. The average size of magnetite particles obtained by XRD data was about 38 nm. Mössbauer spectroscopy showed that magnetite is preserved in the applied synthesis route. Both XPS data and TEM had shown that the silica recovers magnetite particles, forming a composite with particle sizeof 138 nm. Finally, the influence of these magnetic particles in the release kinetic was studied using drugs like cisplatin, carboplatin and atenolol; this study was made under in vitro conditions. The release was studied in absence and presence of a external magnetic field, using a NdFeB permanent magnet of 0,25 T. The kinetic mechanisms and diffusion models were investigated by the external field, and the results had showed a small influence of this parameter on the process of drug release. Considering that nanoparticles are coated by mesoporous silica, this result is expected. Then, a test was made to verify the influence of an oscillating field in the release profile and the results showed a more significant delivery for cisplatin. To explain this fact, an interaction model between this drug and the nanocomposite was proposed.

Tendo como vantagem a elevada resistência ao choque térmico da zircônia:magnésia e a alta condutividade iônica da zircônia:ítria, compósitos dessas cerâmicas foram preparados por meio da mistura, em diferentes concentrações, de eletrólitos sólidos de ZrO2: 8,6 mol% MgO e de ZrO2: 3 mol% Y2O3, compactação e sinterização. A caracterização microestrutural foi feita por meio de difração de raios X e microscopia eletrônica de varredura. A análise do comportamento térmico foi feita por dilatometria. As propriedades elétricas foram estudadas por meio de espectroscopia de impedância. Foi feita uma montagem experimental para monitorar a resposta elétrica gerada em função do teor de oxigênio a altas temperaturas. Os principais resultados mostram que os compósitos cerâmicos são parcialmente estabilizados nas fases monoclínica, cúbica e tetragonal, e apresentam comportamento térmico similar ao apresentado por eletrólitos sólidos de zircônia:magnésia de dispositivos sensores de oxigênio. Além disso, os resultados de análise de espectroscopia de impedância mostram que a adição da zircônia:ítria melhora o comportamento elétrico da zircônia:magnésia, e que resposta elétrica gerada é dependente do teor de oxigênio a 1000 °C, mostrando ser possível construir sensores de oxigênio utilizando compósitos cerâmicos. / Taking advantage of the high thermal shock resistance of zirconia-magnesia ceramics and the high oxide ion conductivity of zirconia-yttria ceramics, composites of these ceramics were prepared by mixing, pressing and sintering different relative concentrations of ZrO2: 8.6 mol% MgO and ZrO2: 3mol% Y2O3 solid electrolytes. Microstructural analysis of the composites was carried out by X-ray diffraction and scanning electron microscopy analyses. The thermal behavior was studied by dilatometric analysis. The electrical behavior was evaluated by the impedance spectroscopy technique. An experimental setup was designed for measurement the electrical signal generated as a function of the amount of oxygen at high temperatures. The main results show that these composites are partially stabilized (monoclinic, cubic and tetragonal) and the thermal behavior is similar to that of ZrO2: 8.6 mol% MgO materials used in disposable high temperature oxygen sensors. Moreover, the results of analysis of impedance spectroscopy show that the electrical conductivity of zirconia:magnesia is improved with zirconia-yttria addition and that the electrical signal depends on the amount of oxygen at 1000 °C, showing that the ceramic composites can be used in oxygen sensors.