Face à la nécessité de trouver des alternatives aux ressources d’origine fossile et de limiter les impacts environnementaux de l’activité humaine, un important effort de recherche est actuellement en cours pour favoriser et accroître l’utilisation de produits issus de ressources renouvelables, comme les fibres végétales, dans la conception de pièces industrielles. Toutefois, de nombreux verrous scientifiques et technologiques restent encore à lever avant de pouvoir valoriser de façon fiable et durable ces fibres dans un contexte technique exigeant tel que celui du secteur l’automobile. Ainsi, l’amélioration de la qualité de l’interface fibres végétales / matrice polymère est un enjeu de taille car elle constitue une condition permettant de satisfaire les performances mécaniques requises telles que la rigidité, la résistance ou la tenue au choc. Dans ce contexte, l’objectif de la thèse a été le développement de fibres courtes de chanvre à propriétés de surface maitrisées et ciblées. Des solutions de fonctionnalisation de surface applicables par des procédés industrialisables ont été développées dans le but d’incorporer ces fibres dans une matrice polypropylène (PP). Les fibres de chanvre ont ainsi été traitées selon différentes stratégies de fonctionnalisation incluant l’utilisant du polypropylène greffé anhydride maléique (PP-g-MA), d’organosilanes, d’un acide aminé, d’isocyanates et d’un polyuréthane. Deux procédés de traitement à faible impact environnemental ont été comparés : le sprayage direct des fibres par les molécules de fonctionnalisation et l’incorporation de ces molécules par extrusion réactive. Les traitements en extrusion réactive se sont montrés plus efficaces que ceux réalisés par sprayage dans le cas du PP-g-MA. Trois voies de fonctionnalisation se sont avérées pertinentes au regard des propriétés mécaniques visées  : i) l’utilisation de PP-g-MA seul en extrusion réactive ; ii) la fonctionnalisation par sprayage d’un aminosilane ou d’un acide aminé couplée à l’incorporation du PP-g-MA en extrusion réactive. S’appuyant sur le développement de moyens expérimentaux et d’analyses spécifiques, l’étude du comportement au choc des biocomposites a montré que les composites renforcés fibres de chanvre permettent d’absorber d’avantage d’énergie que les composites PP / verre (à taux volumique de renfort identique) pour une longueur de fissuration similaire. Une modélisation par éléments finis du comportement au choc des composites étudiés est également proposée. / Due to the necessity to find alternatives to fossil resources and to reduce the environmental impacts of human activity, a major research effort is currently ongoing in order to develop and increase the use of biobased products from renewable resources, such as natural fibers, in the design of industrial parts. However, many scientific and technological hurdles have yet to be removed so as to promote these products before we can reliably and durably use these fibers in a demanding technical context as in automotive sector. Thus, improving the quality of the interface between natural fibers and polymer matrix is a major challenge, since it constitutes a condition for satisfying the required mechanical performances, such as stiffness, tensile or impact strengths. In this context, the thesis objective was to develop short hemp fibers with controlled and targeted surface properties. Surface-functionalization solutions have been developed, to be used by industrial processes, with the aim of incorporating these fibers in a polypropylene (PP) matrix. Therefore, hemp fibers have been treated according to various functionalization strategies including the use of grafted polypropylene maleic anhydride (PP-g-MA), organosilanes, an amino acid, isocyanates and a polyurethane. Two treatments processes, with low environmental impact, were compared: the direct spraying of functionalization molecules on fibers and reactive extrusion incorporation of these molecules. Reactive extrusion treatments were more efficient than those performed by spraying in the case of PP-g-MA. Three functionalization lanes have been found to be relevant regarding the mechanical properties targeted: i) using PP-g-MA alone in reactive extrusion; ii) spraying-functionalization of an aminosilane or of an amino acid coupled with the incorporation of PP-g-MA into the reactive extrusion. Based on the development of experimental means and specific analyzes, the study of the impact behavior of biocomposites has shown that hemp fiber reinforced composites allow to absorb more energy than PP / glass composites (at identical reinforcing volume rate) for a similar crack length. Also, a finite element modeling of the impact behavior of the studied composites is propounded.

Este trabalho realizou um estudo sobre a aplicação de algoritmos de inversão da forma de onda completa (FWI) sobre dados de sísmica de reflexão em uma escala rasa ( 0 100 m de profundidade). A FWI foi estudada com o fim de melhorar as velocidades estimadas através do processamento de reflexão PP e PS convencional. Para um melhor entendimento da resposta obtida por este tipo de problema, a inversão foi avaliada sobre dados sintéticos por métodos de busca global e local. Na busca global foi utilizado o algoritmo de Evolução Diferencial que é uma variante de um algoritmo genético. O intuito da busca global foi avaliar a sensibilidade da função objetivo para cada parâmetro do modelo em diferentes janelas de afastamentos em relação à fonte. Na busca local foi utilizado um algoritmo de gradiente conjugado para a estimativa 2D dos parâmetros do meio. Dentre os principais resultados têm-se que a função objetivo é mais sensível aos parâmetros em janelas de afastamentos próximas da fonte. Em tais janelas, dominadas por ondas superficiais, a velocidade da onda S é facilmente estimada. Entretanto, mesmo em janelas mais afastadas a velocidade da onda S é o parâmetro do modelo que se destaca em relação aos demais. Já a busca por todos os parâmetros concomitantemente mostrou-se difícil e implicaria na necessidade de mais iterações do algoritmo de inversão. O método também foi aplicado em dados reais adquiridos no terreno do Instituto de Física da USP. A FWI foi aplicada nestes dados buscando apenas pelos valores de Vs, mantendo os valores de Vp e densidade fixos. A aplicação do algoritmo 2D nestes dados resultaram em valores de Vs coerentes com as velocidades observadas em um ensaio downhole na área. Concluindo, os resultados apresentados na tese mostram que a FWI é aplicável para a melhoria do modelo de velocidade da onda S obtido através do processamento de eventos de reflexão PP e PS. / This work carried out a study on the application of full waveform inversion algorithms (FWI) on reflection seismic data on a shallow scale (0 - 100 m depth). FWI has been studied in order to improve estimated velocities through conventional PP and PS reflection processing. For a better understanding of the response obtained by this type of problem the inversion was evaluated by global and local search methods. In the global search the algorithm employed was the Differential Evolution which is a variant of a genetic algorithm. The aim of the global search was to evaluate the sensitivity of the objective function for each parameter of the model in different windows of distance from the source. In the local search a conjugate gradient algorithm was used for a 2D estimate of the medium parameters. Among the main results is the fact that in a suitable window, for a reflection data acquisition the sensitivity is reduced in relation to a window with geophones closer to the source. However, even in more distant windows the velocity of the S wave is the parameter of the model that stands out in relation to the others. The concomitant search for all parameters at the same time is still difficult and implies the need for more iterations of the inversion algorithm. The method was also applied in a data acquired in the field of the Institute of Physics of USP. The results of the application of the 2D algorithm for this data showed modifications of the provided initial model for a velocity of the S wave coherent with the observed velocities in downhole and lithological informations from this area. In conclusion, the results found that FWI is applicable to improve the S-wave velocity model obtained by processing PP and PS reflection events.

Este trabalho realizou um estudo sobre a aplicação de algoritmos de inversão da forma de onda completa (FWI) sobre dados de sísmica de reflexão em uma escala rasa ( 0 100 m de profundidade). A FWI foi estudada com o fim de melhorar as velocidades estimadas através do processamento de reflexão PP e PS convencional. Para um melhor entendimento da resposta obtida por este tipo de problema, a inversão foi avaliada sobre dados sintéticos por métodos de busca global e local. Na busca global foi utilizado o algoritmo de Evolução Diferencial que é uma variante de um algoritmo genético. O intuito da busca global foi avaliar a sensibilidade da função objetivo para cada parâmetro do modelo em diferentes janelas de afastamentos em relação à fonte. Na busca local foi utilizado um algoritmo de gradiente conjugado para a estimativa 2D dos parâmetros do meio. Dentre os principais resultados têm-se que a função objetivo é mais sensível aos parâmetros em janelas de afastamentos próximas da fonte. Em tais janelas, dominadas por ondas superficiais, a velocidade da onda S é facilmente estimada. Entretanto, mesmo em janelas mais afastadas a velocidade da onda S é o parâmetro do modelo que se destaca em relação aos demais. Já a busca por todos os parâmetros concomitantemente mostrou-se difícil e implicaria na necessidade de mais iterações do algoritmo de inversão. O método também foi aplicado em dados reais adquiridos no terreno do Instituto de Física da USP. A FWI foi aplicada nestes dados buscando apenas pelos valores de Vs, mantendo os valores de Vp e densidade fixos. A aplicação do algoritmo 2D nestes dados resultaram em valores de Vs coerentes com as velocidades observadas em um ensaio downhole na área. Concluindo, os resultados apresentados na tese mostram que a FWI é aplicável para a melhoria do modelo de velocidade da onda S obtido através do processamento de eventos de reflexão PP e PS. / This work carried out a study on the application of full waveform inversion algorithms (FWI) on reflection seismic data on a shallow scale (0 - 100 m depth). FWI has been studied in order to improve estimated velocities through conventional PP and PS reflection processing. For a better understanding of the response obtained by this type of problem the inversion was evaluated by global and local search methods. In the global search the algorithm employed was the Differential Evolution which is a variant of a genetic algorithm. The aim of the global search was to evaluate the sensitivity of the objective function for each parameter of the model in different windows of distance from the source. In the local search a conjugate gradient algorithm was used for a 2D estimate of the medium parameters. Among the main results is the fact that in a suitable window, for a reflection data acquisition the sensitivity is reduced in relation to a window with geophones closer to the source. However, even in more distant windows the velocity of the S wave is the parameter of the model that stands out in relation to the others. The concomitant search for all parameters at the same time is still difficult and implies the need for more iterations of the inversion algorithm. The method was also applied in a data acquired in the field of the Institute of Physics of USP. The results of the application of the 2D algorithm for this data showed modifications of the provided initial model for a velocity of the S wave coherent with the observed velocities in downhole and lithological informations from this area. In conclusion, the results found that FWI is applicable to improve the S-wave velocity model obtained by processing PP and PS reflection events.

Esta pesquisa se propõe a ser um estudo de caso acerca do Partido do Movimento Democrático Brasileiro, o PMDB. Analiso, de maneira interpretativa, os primeiros anos do partido após a restauração do pluripartidarismo, com um recorte histórico de 1979 - momento da sua (re)fundação em meio ao processo de abertura política - até as eleições de 1982 - momento no qual o partido disputa um pleito pela primeira vez. A análise ressalta a movimentação de grupos internos ao partido, notadamente a existência inicial de uma ala de esquerda herdada do Movimento Democrático Brasileiro - MDB (fenômeno não apontado pela literatura sobre o Partido) e o aumento da heterogeneidade interna do PMDB com o correr dos primeiros anos, como consequência da incorporação do Partido Popular, aspectos esses que são também negligenciados pela literatura. / This study aims to be a study case regarding a specific political party, the Partido do Movimento Democrático Brasileiro, PMDB. I analyze interpretatively its first years after multipartyism restarted in Brazil, in a historical period beginning in 1979, when the party is (re)founded during the democratization, until 1982 elections, when the party faces an election for the first time. The analysis highlights the movement of internal groups within the party, especially the initial existence of a left wing inherited by the Movimento Democrático Brasileiro - MDB (a phenomenon yet mentioned by the literature about the Party) and the increase of PMDB´s internal heterogeneity in the course of its first years, as a result of the merger of the Partido Popular, aspects which are also neglected by the literature.

ABSTRACT CHARACTERIZATION OF SERPENTINE FILLED POLYPROPYLENE Can, Semra Ph.D., Department of Polymer Science and Technology Supervisor: Prof. Dr. Teoman Tin&ccedil / er March 2008, 158 pages In this study, the aim is to prepare polypropylene (PP)/serpentine composites and study their mechanical, thermal and morphological properties. Another objective is to explore whether it is possible to have PP/serpentine nanocomposites with melt intercalation method by using the advantage of the layer silicate structure of serpentine. The most widely used fillers in PP are talc and mica which belong to the phyllosilicates group of silicate minerals. So far, there has been almost no study employing serpentine as filler in either any polymers or PP, although it also belongs to the same group of minerals as talc and mica. Accordingly, it was planned to divide the work into the study of two groups. In group 1, for the compositions with 2, 5, 10 and 20 wt% serpentine, the particulate filler effects of serpentine both alone and in the presence of surface treatments with hydrochloric acid (HCl) and silane coupling agent (SCA) were investigated. The most impressive results in terms of static and dynamic mechanical properties were achieved with SCA rather than HCl. When the effect of serpentine without any treatment is considered, reinforcing effect of it can easily be observed without deteriorating the composite properties even at high filler loadings. In group 2, the nanofiller effects of serpentine in 2 and 5 wt% filled compositions by modification of both the filler and the matrix were aimed to be examined with melt intercalation method. In addition to HCl and SCA treatments, maleic anhydride grafted polypropylene (PP-g-MA) and quaternary ammonium salt (QAS) of cetyl-trimethyl-ammonium bromide were used as compatibilizer and intercalating agent, respectively. While the amount of QAS was kept constant, different percentages of compatibilizer were employed. The presence of QAS and PP-g-MA further improved the properties with respect to group 1 members. Interestingly, the percentage strain at break values did not decrease as much as group 1 compositions with the same filler content. It can be concluded that partial intercalation of group 2 compositions was achieved, according to the X-ray and TEM results. Keywords: Serpentine, PP/serpentine composites, SCA, PP-g-MA, serpentine nanocomposites

Neste trabalho foi feito um estudo do limite de Karlhede para ondas pp. Para este fim, uma revisão rigorosa de Geometria Diferencial foi apresentada numa abordagem independente de sistemas de coordenadas. Além da abordagem usual, a curvatura de uma variedade riemanniana foi reescrita usando os formalismos de referenciais, formas diferenciais e espinores do grupo de Lorentz. O problema de equivalência para geometrias riemannianas foi formulado e as peculiaridades de sua aplicação é a Relatividade Geral são delineadas. O limite teórico de Karlhede para espaços-tempo de vácuo de tipo Petrov N foi apresentado. Esse limite é estudado na prática usando técnicas espinores e as condições para sua existência são resolvidas sem a introdução de sistemas de coordenadas. / In this work a study of the Karlhede limit was made. To this end, a thorough review of Differential Geometry was presented in a coordinate independent approach. Besides the usual approach, the curvature of a riemannian manifold was rewritten using the formalisms of frames, differential forms and Lorentz group spinors. The equivalence problem for riemannian geometries was formulated and the peculiarities of its application to General Relativity are outlined. The theoretical Karlhede limit for vacuum Petrov N space-times is presented. This limit was studied in practice using spinor techniques and the conditions for its existence are solved without introducing coordinate systems.

The use of conformal transformation as a method for generating solutions of Einstein's equations has been mainly studied in the cases where the original spacetime is vacuum. The generated spacetimes then frequently belong to the class of pp-waves. In the present work, the electrovacuum spacetimes are stud- ied, i.e the solutions of coupled Einstein's and Maxwell's equations. By using the conformal transformation, it is possible to circumvent solving the later equa- tions. This method is concretely studied for null Einstein-Maxwell fields and it turns out that the admissible spacetimes are pp-waves again. However, if the method is generalized, it is possible to enlarge the class of conformal null Einstein-Maxwell fields to a wider family of Kundt spacetimes. 1

Neste trabalho foi feito um estudo do limite de Karlhede para ondas pp. Para este fim, uma revisão rigorosa de Geometria Diferencial foi apresentada numa abordagem independente de sistemas de coordenadas. Além da abordagem usual, a curvatura de uma variedade riemanniana foi reescrita usando os formalismos de referenciais, formas diferenciais e espinores do grupo de Lorentz. O problema de equivalência para geometrias riemannianas foi formulado e as peculiaridades de sua aplicação é a Relatividade Geral são delineadas. O limite teórico de Karlhede para espaços-tempo de vácuo de tipo Petrov N foi apresentado. Esse limite é estudado na prática usando técnicas espinores e as condições para sua existência são resolvidas sem a introdução de sistemas de coordenadas. / In this work a study of the Karlhede limit was made. To this end, a thorough review of Differential Geometry was presented in a coordinate independent approach. Besides the usual approach, the curvature of a riemannian manifold was rewritten using the formalisms of frames, differential forms and Lorentz group spinors. The equivalence problem for riemannian geometries was formulated and the peculiarities of its application to General Relativity are outlined. The theoretical Karlhede limit for vacuum Petrov N space-times is presented. This limit was studied in practice using spinor techniques and the conditions for its existence are solved without introducing coordinate systems.

Esta pesquisa se propõe a ser um estudo de caso acerca do Partido do Movimento Democrático Brasileiro, o PMDB. Analiso, de maneira interpretativa, os primeiros anos do partido após a restauração do pluripartidarismo, com um recorte histórico de 1979 - momento da sua (re)fundação em meio ao processo de abertura política - até as eleições de 1982 - momento no qual o partido disputa um pleito pela primeira vez. A análise ressalta a movimentação de grupos internos ao partido, notadamente a existência inicial de uma ala de esquerda herdada do Movimento Democrático Brasileiro - MDB (fenômeno não apontado pela literatura sobre o Partido) e o aumento da heterogeneidade interna do PMDB com o correr dos primeiros anos, como consequência da incorporação do Partido Popular, aspectos esses que são também negligenciados pela literatura. / This study aims to be a study case regarding a specific political party, the Partido do Movimento Democrático Brasileiro, PMDB. I analyze interpretatively its first years after multipartyism restarted in Brazil, in a historical period beginning in 1979, when the party is (re)founded during the democratization, until 1982 elections, when the party faces an election for the first time. The analysis highlights the movement of internal groups within the party, especially the initial existence of a left wing inherited by the Movimento Democrático Brasileiro - MDB (a phenomenon yet mentioned by the literature about the Party) and the increase of PMDB´s internal heterogeneity in the course of its first years, as a result of the merger of the Partido Popular, aspects which are also neglected by the literature.

In this study, commercially available isotactic polypropylene (PP) and nylon-6 (PA6) blends and laminates were prepared, to develop a material with optimal water vapour and oxygen barrier properties. The effect of compatibilizers on phase dispersion has been investigated using three commercial Polybond's, PB3002, PB1001, and PB3009. Three compatibilizers prepared in-house were also used as, maleic anhydride(MA) grafted on PP, MA and butyl methacrylate(BMA) co-polymer grafted on PP, and BMA grafted on low density polyethylene. The effect of two silanes( methacrylate functional and vinyl functional) on PP were also investigated and also the plasticization of PA6 with formic acid. The results were compared with a commercial blend of PP and PA6, Orgalloy R-6000. Light microscopy with phase and fluorescence contrast has been used for morphological evaluation. Chemical changes were studied by Fourier Transform Infrared Spectroscopy and rheology by dynamic and steady state measurements. Barrier properties were determined gravimetrically for water vapour and organic solvents, and for oxygen by an Oxtran apparatus. The results have shown that phase dispersion can be more easily explained by molecular interactions than by the rheological parameters. The blend slip factor has been improved however by compatibilizers and consequently the phase dispersion, which had little effect on the barrier properties of the blends and indeed the laminates were more effective water vapour barriers. The availability of particular functional groups, which can interact with the permeant is the most important parameter, which can be affected by processing and blending conditions. The addition of hydrophobic functional groups into polypropylene was therefore the most effective method for enhancing the barrier properties of polypropylene. Cross-linking of the matrix polymer has improved the barrier properties to a lesser extent. It has also been shown, that PP solvent permeability (particularly di-chloromethane) can be improved, by silane addition.