Dans le cadre du développement de boîtiers à cavités pour composants électroniques, les polymères à cristaux liquides (LCP) offrent des propriétés intéressantes capables de rivaliser avec les matériaux en céramique : une faible perméabilité aux gaz, une résistance à haute température, une stabilité thermique et une faible constante diélectrique (3,1 à 1 MHz et 2,8 à 10 GHz). Cette nouvelle génération de thermoplastiques permettra de concurrencer les boîtiers métalliques et céramiques à cavité plus coûteux et de s’ouvrir à de nouvelles applications comme l’imagerie médicale par exemple.Dans ce contexte, nous proposons une technique de fonctionnalisation de nanoparticules minérales (via procédé Sol-Gel) et leur incorporation à la matrice polymère afin de modifier ces propriétés mécaniques (Module de Young et CTE) et son anisotropie. La fiabilité de boîtiers est évaluée à l’aide de simulations thermomécaniques. Le but est d’établir un lien entre les propriétés mécaniques des composites à base de LCP et la durée de vie des boîtiers électroniques. Le développement de capots optiques pour ces boîtiers est aussi étudié afin d’obtenir une filtration dans la proche infrarouge pour des applications dans le secteur de la téléphonie mobile. / As part of the development of cavities packages for electronic components, Liquid Crystal Polymers (LCP) offer interesting properties and compete with ceramic materials: low gas permeability, high temperature resistance, thermal stability and low dielectric constant (3.1 to 2.8 for 1 MHz and 10 GHz). This new generation of thermoplastic will compete with classic packages more expensive and open to new applications such as medical imaging for example.In this context, we propose an original approach of mineral nanoparticles functionalization (via sol-gel process) and their incorporation into the polymer matrix to modify the mechanical properties (Young's modulus and CTE) and the anisotropy. Packaging reliability is assessed using thermomechanical simulations. The goal is to establish a link between the mechanical properties of composites based on LCP and the characteristic lifetime of the package. The development of optical covers for these packages is also study to obtain a filter in the near infrared for applications in the mobile phone sector.

Made available in DSpace on 2016-06-02T19:55:32Z (GMT). No. of bitstreams: 1 4381.pdf: 2748711 bytes, checksum: 4ba9831d0665b24b6f48f775d30927d2 (MD5) Previous issue date: 2012-04-13 / Universidade Federal de Minas Gerais / The minimization of the emissions of nitrogen oxides (NOx) is a subject of crucial interest, since them cause serious environmental problems which affect human health, vegetation and fauna. With the purpose to abate NOx, processes involving their catalytic reduction show strong potential. In the case of the reduction of NO with CO a meaningful advantage arises, once both pollutants are removed simultaneously. In order to obtain efficient and stable catalysts for this reaction, many studies have been done with the aim to improve the catalytic activity by achieving a better favorable metal-support interaction to the occurrence of the reaction and a better distribution of the active phases on the support. In this context, the objective of this study was to prepare Cu, Fe and Co based catalysts supported on TiO2, CeO2 and ZrO2 to be applied in the abatement of NO with CO. The addition of the precursors of the active phases was made during the synthesis of the support via the sol-gel method (in situ addition). Furthermore, catalysts with the same composition were prepared by conventional methods. Results from the N2 adsorption/desorption measurements show that the sol-gel method was efficient to prepare supports with improved textural properties. H2-TPR and UVVIS-DRS data evidenced the presence of Cu, Fe or Co oxides in the respective catalysts, which mostly did not show characteristic X-ray diffraction peaks of those oxide phases, suggesting their high dispersion on the supports. In general, results of the reduction of NO to N2 with CO revealed that the catalysts prepared via sol-gel are as active as those prepared by conventional routes, which demonstrate the great potential of the catalysts preparation via the sol-gel in situ procedure, which diminishes the number of the synthesis steps saving time and energy. In general, among the studied supports, ceria presented a more favorable metal-support interaction. In the presence of O2, SO2 and water steam, catalysts 6,5Cu/CeP, 5,5CuZrSG and 8,4Fe/TiC showed no significant changes in their activity and selectivity, indicating that they present high stability to be used under the severe conditions of real processes. / A minimização das emissões de óxidos de nitrogênio (NOx) é assunto de interesse crucial, pois geram graves problemas ambientais que afetam à saúde humana, à flora e à fauna. Para abater os NOx, processos envolvendo à sua redução catalítica apresentam forte potencial. No caso da redução catalítica de NO com CO, tem-se a vantagem adicional de minimizar as emissões de ambos poluentes. Para a obtenção de catalisadores eficientes e estáveis para essa reação, muitos estudos têm sido desenvolvidos no sentido de aumentar a atividade por meio de uma interação metalsuporte mais favorável ao processo reativo e de se conseguir uma melhor distribuição da fase ativa no suporte. Nesse contexto, o objetivo do presente estudo foi preparar catalisadores para a redução de NO com CO à base de óxido de Cu, Fe ou Co, suportados em TiO2, CeO2 ou ZrO2, com a adição do precursor da fase ativa durante a preparação do suporte via processo sol-gel (adição in situ). Além disso, catalisadores de mesma composição foram preparados por rotas convencionais. Resultados de medidas de adsorção/dessorção de N2 dos suportes mostram que o método sol-gel utilizado é mais eficiente no preparo de suportes com propriedades texturais melhoradas. Análises de RTP-H2 e ERD-UVVIS evidenciaram a presença dos óxidos de Cu, Fe ou Co em todos os catalisadores, os quais, em sua maioria, não apresentaram picos de difração de raios X característicos dessas fases, o que sugeriu sua alta dispersão no suporte. Em geral, os resultados da redução de NO a N2 com CO mostraram que os catalisadores preparados pelo método sol-gel in situ são tão ativos quanto os catalisadores preparados por métodos convencionais, o que demonstra o forte potencial desse procedimento, que resulta no uso de um número menor de etapas na preparação do catalisador, com a consequente economia de tempo e energia. De maneira geral, dentre os suportes estudados a céria mostrou uma relação metal-suporte mais favorável ao processo de óxidoredução. Os catalisadores 6,5Cu/CeP, 5,5Cu-ZrSG e 8,4Fe/TiC, na presença de O2, SO2 e vapor de água não apresentaram alteração significativa da sua atividade e seletividade, mostrando uma alta estabilidade para atuar sob as drásticas condições dos processos reais.