A simple capillary flow porometer (CFP) was assembled for pore structure characterization of monolithic capillary liquid chromatography columns based on ASTM standard F316-86. Determination of differential pressures and flow rates through dry and wet samples provided the necessary information to determine the through-pore throat diameter, bubble point pore diameter, mean flow pore diameter, and pore distribution. Unlike measurements in bulk using traditional techniques to provide indirect information about the pore properties of monolithic columns, monoliths can be characterized in their original chromatographic forms with this system. The performance of the new CFP was first evaluated by characterizing the pore size distributions of capillary columns packed with 3, 5, and 7 µm spherical silica particles. The mean through-pore diameters of the three packed columns were measured to be 0.5, 1.0 and 1.4 µm, which are all smaller than the pore diameters calculated from a close-packed arrangement (i.e., 0.7, 1.1 and 1.6 µm), with distributions ranging from 0.1 - 0.7, 0.3 - 1.1 and 0.4 - 2.6 µm, respectively. This is reasonable, since visual inspection of SEM images of the particles showed relatively large fractions of smaller than specified particles in the samples. Typical silica monoliths were fabricated via phase separation by polymerization of tetramethoxysilane (TMOS) in the presence of poly(ethylene glycol) (PEG). The mean pore diameter and pore size distribution measured using the CFP system verified that a greater number of pores with small throat diameters were prepared in columns with higher PEG content in the prepolymer mixture. SEM images also showed that the pore diameters of monoliths fabricated in bulk were found to be smaller than those in monoliths synthesized by the same procedure, but confined in capillary tubes. The CFP system was also used to study the effects of column inner diameter and length on pore properties of polymeric monoliths. Typical monoliths based on butyl methacrylate (BMA) and poly(ethylene glycol) diacrylate (PEGDA) in capillary columns with different inner diameters (i.e., 50 to 250 µm) and lengths (i.e., 1.5 to 3.0 cm) were characterized. The mean pore diameters and the pore size distributions indicated that varying the inner diameter and/or the length of the column affected little the pore properties. The latter finding is especially important to substantiate the use of CFP for determination of monolithic pore structures in capillaries. The results indicate that the through-pores are highly interconnected and, therefore, pore structure determinations by CFP are independent of capillary length. A negatively charged polymer monolith based on BMA, ethylene glycol dimethacrylate (EDMA) and 2-acryloylamido-2-methylpropanesulfonic acid monomer (AMPS), was successfully prepared in silica sacrificial layer, planar (SLP) microchannels. Extraction of FITC (fluorescein 5-isothiocyanate) labeled phenylalanine and capillary electrochromatography (CEC) of FITC labeled glycine using this monolithic stationary phase were demonstrated.

Mesoporous γ-alumina is the most extensively used catalysts support in a wide range of catalytic processes. The usefulness of γ-alumina relies on its favorable combination of physical, textural, thermal, and chemical properties. Pore structure properties are among the most important properties, since high surface area and large pore volume enable higher loading of active catalytic phases, while design of pore size and pore size distribution is critical to optimize pore diffusional transport and product selectivity. In addition, accurate determination of surface area (SA), pore volume (PV) and pore size distribution (PSD) of porous supports, catalysts, and nanomaterials is vital to successful design and optimization of these materials and to the development of robust models of pore diffusional resistance and catalyst deactivation.In this dissertation, we report a simple, one-pot, solvent-deficient process to synthesize mesoporous γ-alumina without using external templates or surfactants. XRD, TEM, TGA and N2 adsorption techniques are used to characterize the morphologies and structures of the prepared alumina nanomaterials. By varying the aluminum salts or the water to aluminum molar ratio in the hydrolysis of aluminum alkoxides, γ-alumina with different morphologies and pore structures are synthesized. The obtained alumina nanomaterials have surface areas ranging from 210 m2/g to 340 m2/g, pore volumes ranging from 0.4 cm3/g to 1.7 cm3/g, and average pore widths from 4 to 18 nm. By varying the alcohols used in the rinsing and gelation of boehmite/bayerite precursors derived from a controlled hydrolysis of aluminum alkoxides, the average pore width of the γ-aluminas can be tuned from 7 to 37 nm. We also report improved calculations of PSD based on the Kelvin equation and a proposed Slit Pore Geometry model for slit-shaped mesopores of relatively large pore size (>10 nm). Two structural factors, α and β, are introduced to correct for non-ideal pore geometries. The volume density function for a log normal distribution is used to calculate the geometric mean pore diameter and standard deviation of the PSD. The Comparative Adsorption (αs) Method is also employed to independently assess mesopore surface area and volume.

This cumulative dissertation is a compendium of five peer-reviewed and published scientific papers on developing an advanced NMR Cryoporometry toolbox for pore architecture characterization. The dissertation contains five chapters. The first introduces porous materials, their types and applications. Chapter two describes the fundamentals of fluid phase equilibria in mesoporous solids and how modifications of the well-known Laplace equation describe various fluid phase equilibria. The basic principles of the Gas Sorption and NMR Cryoporometry techniques are discussed. In chapter three, different characterization techniques are amalgamated onto a common framework which can be used to compare fluid phase coexistence in porous materials of different pore sizes. Chapter four explains a completely new NMR Cryoporometry characterization methodology developed for cylindrical and spherical pore shapes. Chapter five concludes and crowns the present work by discussing the complementary benefits of the advanced technique in characterizing random porous materials and accounting for pore connectivity effects. All materials synthesized for the work in this dissertation have been obtained through collaborations with the groups of Profs. Dr. Michael Fröba and Simone Mascotto of the Hamburg University and Prof. Dr. Dirk Enke of the Leipzig University.:Table of Contents Thesis Summary ........................................................................................................1 List of publications ......................................................................................................2 Acknowledgements ...................................................................................................4 CHAPTER 1:.............................................................................................................10 Introduction ..............................................................................................................10 CHAPTER 2:.............................................................................................................12 Fluid Phase Equilibria in Mesoporous Solids ..........................................................12 2.1 Gas Sorption................................................................................................... 13 2.1.1 Adsorption Isotherms................................................................................ 15 2.1.2 Adsorption Hysteresis............................................................................... 18 2.1.3 Scanning Behavior.................................................................................... 23 2.2 NMR Cryoporometry ....................................................................................... 25 2.2.1 Pore Size Distribution (PSD)....................................................................... 28 2.3 Serially-Connected Pore Model (SCPM)......................................................... 29 2.4 Problem Statement ......................................................................................... 30 CHAPTER 3:..............................................................................................................32 Analogy between Characterization Techniques ......................................................32 • Publication 3. On the Comparative Analysis of Different Phase Coexistences in Mesoporous Materials CHAPTER 4:.............................................................................................................42 An Advanced NMR Cryoporometry Approach.........................................................42 • Publication 4.1. Nuclear Magnetic Resonance Cryoporometry Study of Solid−Liquid Equilibria in Interconnected Spherical Nanocages • Publication 4.2. A novel approach for advanced thermoporometry characterization of mesoporous solids: Transition kernels and the serially connected pore model CHAPTER 5:.............................................................................................................65 Characterizing Random Porous Materials................................................................65 • Publication 5.1. Comparative Gas Sorption and Cryoporometry Study of Mesoporous Glass Structure: Application of the Serially Connected Pore Model • Publication 5.2. Impact of Geometrical Disorder on Phase Equilibria of Fluids and Solids Confined in Mesoporous Materials Appendix A:.............................................................................................................100 Porous Solid Characterization Techniques............................................................100 A.1: Mercury Intrusion Porosimetry (MIP) ........................................................... 100 A.1.1. Experimental Set-up.............................................................................. 101 A.2: Gas Sorption................................................................................................ 103 A.2.1. Experimental Set-Up ............................................................................. 103 A.2: NMR Cryoporometry.................................................................................... 106 A.2.2. Experimental Set-Up ............................................................................. 106 Appendix B:..............................................................................................................109 Supporting information ............................................................................................109 Appendix C:.............................................................................................................115 Author contributions ................................................................................................115 Bibliography ............................................................................................................117

Background: Separation science is heavily reliant on materials to fulfill ever more complicated demands raised by other areas of science, notably the rapidly expanding molecular biosciences and environmental monitoring. The key to successful separations lies in a combination of physical properties and surface chemistry of stationary phases used in liquid chromatographic separation, and this thesis address both aspects of novel separation materials. Methods: The thesis accounts for several approaches taken during the course of my graduate studies, and the main approaches have been i) to test a wild-grown variety of published methods for surface treatment of fused silica capillaries, to ascertain firm attachment of polymeric monoliths to the wall of microcolumns prepared in silica conduits; ii) developing a novel porogen scheme for organic monoliths including polymeric porogens and macromonomers; iii) evaluating a mesoporous styrenic monolith for characterization of telomers intended for use in surface modification schemes and; iv) to critically assess the validity of a common shortcut used for estimating the porosity of monoliths prepared in microconduits; and finally v) employing plasma chemistry for activating and subsequently modifying the surface of rigid, monodisperse particles prepared from divinylbenzene. Results: The efforts accounted for above have resulted in i) better knowledge of the etching and functionalization parameters that determine attachment of organic monoliths prepared by radical polymerization to the surface of silica; ii) polar methacrylic monoliths with a designed macroporosity that approaches the desired "connected rod" macropore morphology; iii) estab¬lishing the usefulness of monoliths prepared via nitroxide mediated polymerization in gradient polymer elution chromatography; iv) proving that scanning electron microscopy images are of limited value for assessing the macroporous properties of organic monoliths, and that pore measurements on externally polymerized monolith cocktails do not represent the porous properties of the same cocktail polymerized in narrow confinements; and v) showing that plasma bromination can be used as an activation step for rigid divinylbenzene particles to act as grafting handles for epoxy-containing telomers, that can be attached in a sufficiently dense layer and converted into carboxylate cation exchange layer that allows protein separations in fully aqueous eluents.

Deux approches pour caractériser les milieux poreux en terme de distribution de taille de pores (DTP) sont développées au sein de l'équipe ECPS. Ce travail a pour but de confirmer expérimentalement leurs validités. A l'instar des autres méthodes utilisant l'intrusion du mercure, l'adsorption isotherme ou la thermoporosimétrie, la première méthode consiste à utiliser un fluide à seuil d'écoulement. En effet, l'utilisation de l'écoulement d'un fluide à seuil de type Herschel-Bulkley, au travers d'un poreux, en fonction du gradient de pression permet (en utilisant les solutions analytique et numérique du problème inverse) de déterminer la fonction de distribution de la taille de pores. La seconde méthode utilise l'admittance complexe d'un milieu poreux, mesurée à partir de la réponse en débit à une sollicitation harmonique du gradient de pression. Comme la fréquence de la sollicitation est reliée aux rayons des pores par le biais de la profondeur de pénétration hydrodynamique, l'admittance permet de retrouver la distribution de taille de pores par la résolution numérique du problème inverse associé. Ces deux techniques sont basées sur le modèle de faisceaux de capillaires parallèles employé dans la plupart des autres études qui traitent du même problème. Nos expériences s'appuient sur des milieux poreux calibrés. L'application de ces techniques aux milieux poreux réels se fait actuellement en collaboration avec le TREFLE de Bordeaux. Les résultats expérimentaux obtenus affirment clairement la validité et l'applicabilité de ces deux méthodes pour la caractérisation de la DTP. Il est désormais envisageable de les transférer pour un usage industriel. / Two approaches to characterize porous media in terms of pore size distribution (PSD) are developed within our ECPS team. The aim of this study is to experimentally confirm their validity. Like the other methods using mercury intrusion, adsorption isotherm or thermoporometry, the first method consists in the use of a fluid flow threshold. Indeed, the use of flow of a yield-stress fluid like those of Herschel-Bulkley's, through a porous media, versus the pressure gradient, permits (using the analytical and numerical solutions of the inverse problem) to determine the distribution function of its PSD. The second method uses the complex admittance of a porous medium, measured from the flow rate response to a harmonic pressure gradient. As the frequency of the sollicitation is related to the pore radius through the hydrodynamic penetration depth, the admittance allows to determine the PSD using numerical solution of the associated inverse problem. Both techniques are based on the parallel capillaries bundle model, as used in most of similar studies. Our experiments use calibrated porous media. The application of these techniques to real porous media is currently lead in collaboration with the TREFLE (Bordeaux). Our experimental results clearly confirm the validity and the applicability of these methods for the characterization of the PSD. It is now possible to transfer them for an industrial use.

Les méthodes expérimentales utilisées actuellement pour déterminer la distribution de taille des pores (DTP) dans les milieux poreux présentent des inconvénients, tels que par exemple, la toxicité des fluides employés (porosimétrie à mercure). La base théoriques d'une nouvelle méthode pour obtenir la DTP a été proposée dans la littérature. Celle-ci est fondée sur l'injection de fluides à seuil, caractérisés par une contrainte de cisaillement en deçà de laquelle ils ne s'écoulent pas. L'idée principale de ces travaux théoriques est que l'écoulement de fluides à seuil à travers un milieu poreux permet d'obtenir sa DTP à partir de la mesure des débits correspondant à différents gradients de pression Q(∇P). L'objectif du travail proposé ici est de présenter une nouvelle méthode d'exploitation des données expérimentales Q(∇P) permettant d'obtenir de façon simple, robuste et reproductible les DTPs des milieux poreux analysés. La démarche consiste à évaluer la contribution au débit total des nouveaux pores qui s'incorporent à l'écoulement entre deux valeurs de ∇P. Ces nouveaux pores sont caractérisés par un rayon représentatif qui est fonction de la contrainte seuil du fluide et de ∇P. L'importance de leur contribution au débit total par rapport à celle d'un seul pore donne le nombre de pores dans l'échantillon ayant ce rayon représentatif. Cette méthode est d'abord testée et validée avec des expériences générées numériquement. Ensuite, elle est utilisée pour exploiter des données provenant d'expériences de laboratoire réalisées avec de différents milieux poreux. Les résultats obtenus en termes de DTPs sont comparés avec ceux fournis par d'autres techniques: porosimétrie à mercure et microtomographie. / Current experimental methods used to determine pore size distributions (PSD)of porous media present several drawbacks such as toxicity of the employed fluids (e.g., mercury porosimetry). The theoretical basis of a new method to obtain the PSD by injecting yield stress fluids through porous media and measuring the flow rate Q at several pressure gradients ∇P was proposed in the literature. On the basis of these theoretical considerations,an intuitive approach to obtain PSD from Q(∇P) is presented in this work. It relies on considering the extra increment of Q when ∇P is increased, as a consequence of the pores of smaller radius newly incorporated to the flow. This procedure is first tested and validated on numerically generated experiments. Then, it is applied to exploit data coming from laboratory experiments and the obtained PSDs are compared to those deduced by mercury porosimetry and micro tomography.

Poröse Materialien sind von großer Bedeutung in verschiedenen Anwendungsbereichen und sind weit verbreitet sowohl in natürlicher oder technischer Herkunft. Ihre Eigenschaften werden in hohem Maße von der Struktur des Porenraumes bestimmt, die durch quantitative Parameter wie Porosität oder Porengrößenverteilung beschrieben werden kann. Für die Untersuchung poröser Materialien stehen verschiedene indirekte Porosimetrieverfahren zur Verfügung, die jedoch bei sehr großen Poren in der Größenordnung oberhalb von 10 um nur eingeschränkt anwendbar sind. Aus diesem Grund war das Ziel dieser Arbeit die Entwicklung eines Verfahrens zur direkten Charakterisierung großporiger Werkstoffe. Dabei sollte die NMR- Mikroskopie zur dreidimensionalen Abbildung des Porensystems verwendet werden und mit einer anschließenden Bildverarbeitung quantitative Parameter wie die Porengrößenverteilung ermittelt werden. Für die experimentellen Untersuchungen wurden zwei unterschiedliche Filtermaterialien ausgewählt, die Porengrößen oberhalb von 10 µm aufwiesen. Für die NMR-mikroskopische Abbildung des Porenraumes wurden die Materialien mit unterschiedlichen Intrusionsflüssigkeiten gefüllt, wobei dest. Wasser, Octamethylcyclotetrasiloxan und Dimethylsulfoxid verwendet wurden. Die NMR-mikroskopische Abbildung des Porenraumes erfolgte anhand der Protonen der verwendeten Intrusionsflüssigkeit, wobei eine 3D-Spinechopulssequenz verwendet wurde. Die maximal erreichte räumliche Auflösung lag bei einer Größe der isotropen Voxel von ca. 12 um. Weiterhin wurde von ausgewählten Proben dreidimensionale Aufnahmen mit der Röntgencomputertomographie angefertigt, sowie für einige Proben Messungen mit der Quecksilberporosimetriemessungen durchgeführt. Für die Auswertung der NMR-Mikroskopieaufnahmen wurde auf der Basis der kommerziellen Softwarebibliothek HORUS ein eigenes Bildverarbeitungsprogramm entwickelt. Dieses Programm analysiert schichtweise den 3D-Bilddatenstatz und ermittelt daraus Porengrößenverteilungen und Porenkanäle senkrecht zur Bildebene. Die Ergebnisse der Bildverarbeitung der NMR-Mikroskopieaufnahmen zeigen für die Glasfilterproben gute Übereinstimmungen mit den Herstellerangaben zu den Materialien. Die für die unterschiedlichen Glasfiltersorten ermittelten Porengrößenverteilungen widerspiegeln sowohl in ihren absoluten Werten als auch im Verhältnis zueinander gut die nominellen Porenweiten der ausgewählten Materialien. Die mit der Quecksilberintrusion ermittelten Porengrößenverteilungen zeigen eine Beziehung zu den durch die Bildverarbeitung ermittelten minimalen Weiten der Porenkanäle. Für die untersuchten Polyethylensintermaterialien wurden Porengrößenverteilungen ermittelt, die von den Herstellerangaben abweichen. Untersuchungen mit Quecksilberintrusionsmessungen und Elektronenmikroskopieaufnahmen ergaben ähnliche Resultate und stützten dadurch die NMR-mikroskopisch ermittelten Ergebnisse. Im Rahmen der Arbeit konnte gezeigt werden, daß sich die NMR-Mikroskopie in Verbindung mit der digitalen Bildverarbeitung gut für die quantitative Charakterisierung großporiger nichtmetallischer Systeme eignet. Es wurden entsprechende Bildverarbeitungsroutinen entwickelt und die experimentellen Bedingungen hinsichtlich der Steigerung der räumlichen Auflösung optimiert. / Porous materials are of great importance for many application and are widespread as well in their natural as in their technical occurence. Their properties are determined to a high degree by the structure of the pore space, which can be described quantitativly with parameters like porosity or pore size distribution. There are a number of indirect porosimetry methods for porous materials, however most of them are less suitable for large pores in the range above 10 microns. For this reason it was the purpose of the undertaken investigations to develop a method for the direct characterization of materials with large pores. The intention was to use the nmr microscopy for the three-dimensional imaging of the pore system and to determine quantitative parameters like the pore size distribution with a suitable image processing algorithm. For the experimental investigations two different filter materials were selected, which had pore widths larger than 10 microns. For the nmr microscopy imaging of the pore space the materials were filled with different intrusion fluids using distilled water, octamethylcyclotetrasiloxane, and dimethylsulfoxide. For the nmr microscopy imaging of the pore space the protons of the intrusion fluid were selected, using a three-dimensional spin echo sequence. The highest spatial resolution in the nmr microscopy experiments was at a size of approximately 12 microns for an isotropic voxel. Furthermore for a selected range of glass filter samples three-dimensional images were acquired with X-ray tomography and a number of samples were investigated with mercury porosimetry. For the analysis of the nmr microscopy data an image processing algorithm was programmed basing on the commercial imaging software library HORUS. This program sequentially analyses the slices of the 3D imaging dataset and calculates pore size distributions and extracts pore channels perpendicular to the slice plane. The results of the image processing of the nmr microscopy data show a good agreement with the manufactures specification for the glass filter, regarding the absolute values for the calculated pore size distributions and the relative values for different glass filter materials. The pore size distributions which were determined with mercury porosimetry show a good agreement with the minimal pore channel widths as they were determined from the image processing of the nmr microscopy data. The calculated pore size distributions of the investigated polyethylene sinter materials differed from the manufacturers specification. Investigations with mercury intrusion experiments and electron microscopy images gave similar results thus supporting the results from the nmr microscopy experiments. Within the scope of this work it could be demonstrated, that nmr microscopy in connection with a digital image analysis is very suitable for the quantitative characterization of non-metallic systems with large pores. The necessary image processing algorithms have been developed and the experimental parameters have been optimised in order to maximise the spatial resolution of the nmr microscopy images.

Made available in DSpace on 2017-07-21T19:26:10Z (GMT). No. of bitstreams: 1 Jocenei Antonio Oliveira.pdf: 2309316 bytes, checksum: 8527d62e93fbe03d332c4ffaa65aedda (MD5) Previous issue date: 2014-06-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Soil water retention properties can be described by so-called soil-water characteristic curve (SWCC) or retention curve (WRC). This curve expresses the relationship between matric potential and soil moisture based on weight or volume. Through the attainment and subsequent analytical interpolation of the WRC, it’s possible the indirect estimative of the pore-size distribution (PSD) curve of any porous system. Sometimes, obtaining the WRC may be a time-consuming process or involve the use of equipment not available in some laboratories. Thus the development of an alternative method to obtain the WRC and after the PSD becomes desirable, since these are properties of extreme importance to characterize porous media. The main objective of this study is to create and adapt methodology for obtaining PSD using computer simulation in tomographic images with micrometer resolution. In this study, there were used samples of sand and glass beads of different grain sizes for the generation of the PSD curve using a Haines’ funnel on balance. After WRC achievement, these were adjusted through an analytical model and then there were built experimental PSD curve. PSD were also determined by adaptation of a computer program using tomographic images of these samples. The results of obtained WRC associated with geometric models to predict the entry point of air have only revealed the idea about how may occur drying of the samples, showing only morphological considerations are not sufficient to describe this situation. The investigated porous systems homogeneity was able to be visualized by comparing the PSD curves in terms of their widths. / Propriedades de retenção da água no solo podem ser descritas pela chamada curva característica de água no solo ou curva de retenção (CR). Esta curva exprime a relação entre potencial mátrico e a umidade do solo à base de massa ou volume. Mediante o levantamento da CR e posterior interpolação analítica, pode-se estimar indiretamente a curva de distribuição de poros (CDP) de um sistema poroso qualquer. Algumas vezes, a obtenção da CR pode ser um processo demorado ou envolver a utilização de equipamentos não disponíveis em alguns laboratórios. Desta forma, o desenvolvimento de uma metodologia alternativa para a obtenção da CR e posteriormente da CDP se faz desejável, uma vez que se trata de propriedade de extrema importância para a caracterização de um meio poroso. O objetivo principal deste trabalho é criar e adaptar metodologia para a obtenção de CDPs utilizando simulação computacional em imagens tomográficas com resolução micrométrica. No presente estudo, foram utilizadas amostras de areias e esferas de vidro de diferentes granulometrias para o levantamento das CRs usando um funil de Haines adaptado. Depois de obtidas as CRs, essas foram ajustadas através do modelo de ajuste de van Genuchten e obtidas as CDPs (primeira derivada da CR). Também foram obtidas CDPs mediante a adaptação de um programa computacional que utiliza informações de imagens tomográficas dessas amostras. Os resultados das CDPs levantadas pelos dois métodos mostram alguma concordância. Verificou-se, no entanto, que apenas considerações sobre a morfologia dos poros não são suficientes para descrever a forma com que as amostras são drenadas.

Resumo: O sistema de semeadura direta (SSD) proporciona melhores condições físicas do solo favorecendo o armazenamento de água no solo (ARM). A hipótese do trabalho foi que o Latossolo Vermelho argiloso, em sequências de culturas de verão e inverno sob SSD afeta o ARM em decorrência da modificação nos atributos físicos do solo e que o tensiômetro de punção digital (TDig) pode ser usado para medir o potencial mátrico da água no solo. Os objetivos foram avaliar o ARM e os atributos físicos do solo em sequências de culturas de verão e de inverno sob SSD e medir o potencial mátrico da água no solo por meio do tensiômetro de mercúrio e do TDig. O delineamento foi em blocos, com três repetições, no esquema em faixas. Os tratamentos foram constituídos por três sequências de culturas de verão (rotação soja/milho e monocultura de milho e soja) e sete culturas de inverno (milho, girassol, nabo forrageiro, milheto, guandu, sorgo e crotalária). Foram instalados tensiômetros nas camadas de 0,2; 0,4 e 0,6 m. Foi determinada a densidade do solo, a distribuição de poros por tamanho nas camadas de 0-0,1 e 0,1-0,2 m e a infiltração de água na superfície do solo. Os dados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey. O TDig pode ser usado para avaliar o potencial mátrico da água no solo. O ARM não diferiu entre as sequências de culturas de verão e nas culturas de inverno houve diferença, principalmente após período de menor disponibilidade hídrica. A densidade e a porosidade do solo não foram influenciadas pelas culturas de verão e inverno. O diâmetro de poros entre 0,075 - 0,05 e 0,03 - 0,0375 mm na camada de 0,0-0,1 m diferiu entre as sequências de verão. A distribuição de poros por tamanho não foi influenciada pelas sequências de culturas de inverno. A maior infiltração de água no solo ocorreu na parcela sob monocultura de soja / Abstract: No tillage system provides soil physical properties improvements, and soil water storage. The hypothesis of this study was that a Red Latosol (Oxisol), in summer and winter crops sequences under no-tillage system, can have its soil water storage influenced by changes in soil physical properties and digital tensiometer can be used to measure soil water matric potential. This study aimed to measure the soil matric potential using both mercury and digital tensiometers and to evaluate the soil water storage and physical properties on summer and winter crops sequences under no-tillage system. A completely randomized block was designed with three replications on a strips plan. The treatments were the combination of three summer crops sequences (soybean/maize rotation, corn and soybean monocultures) and seven winter crops (maize, sunflower, oilseed radish, millet, pigeon pea, sorghum and sunn hemp). Tensiometers were installed at a depth of 0.20; 0.40; 0.60 meters. Bulk density and pores distribution curves were determined from layers 0-0.1 and 0.1-0.2 depth and water infiltration at the soil surface. The data were submitted to variance analysis and means were compared by the Tukey test. The hypothesis was confirmed, therefore digital tensiometer can be used to measure soil water matric potential. The results showed no difference regarding soil water storage in summer crops sequences, especially after a period associated with lower water availability. Soil porosity and bulk density were not influenced by summer and winter crops sequences. The results indicated that the pores with diameter between 0,075 - 0,05 e 0,03 - 0,0375 mm from layer 0-0.1 m differed on summer crops sequences. No difference was observed by pores distribution curves between summer and winter crops sequences. The largest water infiltration occurred under the soybean monocultures plot / Orientador: José Eduardo Corá / Coorientadora: Carolina Fernandes / Banca: Antonio Evaldo Klar / Banca: Vilson Antonio Klein / Banca: Maria Helena Moraes / Banca: José Renato Zanini / Doutor

L’accident de Fukushima a démontré qu’aujourd’hui encore, malgré les progrès déjà réalisésdans le domaine de la sûreté nucléaire, une interruption prolongée du circuit de refroidissement primaire du réacteur (plusieurs semaines ici) était possible. La France s’est par conséquent vue contrainte de réévaluer le niveau de sûreté de ses centrales. Plus spécifiquement, le cas le plus défavorable qu’EDF considérait jusqu’alors, qui consistait en un arrêt total du système de refroidissement primaire de 24h, a été réévalué à deux semaines. Ce changement d’échelle temporelle a introduit des problématiques de fluage, d’évolution hygrométrique du béton ainsi que de flux de vapeur – celle-ci transportant les radionucléides – jusque-là laissées de côté. De ces considérations est né le projet ANR/RSNR MACENA (MAîtrise du Confinement d’une ENceinte en Accident), qui vise à évaluer le confinement d’une enceinte soumise à une température de 180°C et à une pression de 5 bar pendant deux semaines. Ce travail s’inscrit dans la lignée de celui entamé par Khaddour [2014] dans le but de parvenir à une meilleure prédiction des propriétés de transport des milieux poreux en se basant uniquement sur une caractérisation indirecte, la distribution des tailles de pore obtenue grâce à la technique de porosimétrie par intrusion de mercure. Si l’aptitude du modèle initial à estimer correctement les perméabilités intrinsèques a été confirmée sur des matériaux représentant une large gamme de perméabilités, il n’était pas, en l’état, capable de prédire les perméabilités relatives au gaz et au liquide. C’est pourquoi une approche dite redistributive a été développée, laquelle a montré de bons résultats sur diverses PSD. Enfin, un nouveau modèle a été développé pour essayer de s’affranchir de cette approche tout en améliorant la capacité à déterminer les perméabilités relatives. Bien qu’efficace sur des PSD monomodales, étroites ou larges, il a montré ses limites sur une PSD réelle bimodale. En parallèle, une étude de faisabilité a exhibé la possibilité de suivre un front de saturation à l’intérieur d’un matériau poreux, ce qui permettrait à terme de valider l’inclusion d’autres phénomènes dans le modèle, liés notamment à la pression de perçage. / The Fukushima catastrophe that struck Japan in 2011 demonstrated that despite significant progress in the field of nuclear safety a prolonged reactor primary cooling circuit breakdown was possible (several weeks in this specific case). With 4 nuclear power plants located on its shoreline, France therefore needed to reassess the safety level of its facilities. More specifically, the worst case scenario considered up until that point by EdF — which consisted in a 24h breakdown of the primary cooling system — was revised up to two weeks. This time-scale shift induced creep, drying and vapour flow problems previously left aside. Thus came to be the ANR/RSNR MACENA (MAîtrise du Confinement d’une ENceinte en Accident) project, which aims at bettering the tightness assessment of a nuclear containment vessel submitted to a temperature of 180°C and to a pressure of 5 bar for two weeks. This work falls in line with that initiated by Khaddour [2014], who set out to better predict porous materials’ transport properties based solely on an indirect characterisation of their topology, namely Pore Size Distribution (PSD) which is obtained via an experimental technique called Mercury Intrusion Porosimetry (MIP). The initial model’s ability to correctly estimate intrinsic permeabilities was confirmed on several different materials whose intrinsic permeabilities span several orders of magnitude. However, it was not fit to accurately account for gas and liquid relative permeabilities. This led to the introduction of a so-called redistributive approach, which yielded better results on various PSD and corresponding experimental datasets. Finally, a new model was developed to try and avoid said approach while bettering relative permeability predictions. Although it behaved well with monomodal pore size distributions, be they wide or narrow, it fell short when applied to a real bimodal PSD. In parallel, an experimental feasibility study demonstrated the possibility of tracking a saturation front within a porous material, which should ultimately allow for the implementation of several other phenomena into the model, linked among others to breakthrough capillary pressure.