The purpose of this study was first to develop a method by which a detailed porosity classification system could be utilized to understand the relationship between pore/pore-throat geometry, genetic porosity type, and facies. Additionally, this study investigated the relationships between pore/pore-throat geometry, petrophysical parameters, and reservoir performance characteristics. This study focused on the Jurassic Smackover reservoir rocks of Grayson field, Columbia County, Arkansas. This three part study developed an adapted genetic carbonate pore type classification system, through which the Grayson reservoir rocks were uniquely categorized by a percent-factor, describing the effect of diagenetic events on the preservation of original depositional texture, and a second factor describing if the most significant diagenetic event resulted in porosity enhancement or reduction. The second part used petrographic image analysis and mercury-injection capillary pressure tests to calculate pore/pore-throat sizes. From these data sets pore/pore-throat sizes were compared to facies, pore type, and each other showing that pore-throat size is controlled by pore type and that pore size is controlled primarily by facies. When compared with each other, a pore size range can be estimated if the pore type and the median pore-throat aperture are known. Capillary pressure data was also used to understand the behavior of the dependent rock properties (porosity, permeability, and wettability), and it was determined that size-reduced samples, regardless of facies, tend to show similar dependent rock property behavior, but size-enhanced samples show dispersion. Finally, capillary pressure data was used to understand fluid flow behavior of pore types and facies. Oncolitic grainstone samples show unpredictable fluid flow behavior compared to oolitic grainstone samples, yet oncolitic grainstone samples will move a higher percentage of fluid. Size-enhanced samples showed heterogeneous fluid flow behavior while the size-reduced samples could be grouped by the number of modes of pore-throat sizes. Finally, this study utilized petrographic image analysis to determine if 2- dimensional porosity values could be calculated and compared to porosity values from 3-dimensional porosity techniques. The complex, heterogeneous pore network found in the Grayson reservoir rocks prevents the use of petrographic image analysis as a porosity calculation technique.

As a low cost natural polymer, starch is widely used in paper, food, adhesive, and many other industries. In order to improve the performance of starch, crosslinking is often conducted either in the processes of starch modification or during the application processes. Many crosslinkers have been developed in the past for crosslinking starch. Ammonium zirconium carbonate (AZC) is one of the common crosslinkers for crosslinking starch in aqueous solutions, having been widely used as a starch crosslinking agent in paper surface coating for more than 20 years. However, the mechanisms of starch crosslinking with AZC have not been well studied. In order to optimize the crosslinking chemistry of starch and find new paths for the utilization of starch in papermaking, a better understanding of the starch crosslinking mechanism is necessary. This thesis focuses on the fundamental study of starch crosslinking in an aqueous solution and its applications in fiber surface grafting, filler modification, and starch nanoparticle formation. Particularly, the thesis contains three major parts: (1) Mechanism study of starch crosslinking induced by AZC: In this thesis, the crosslinking (or gelation) kinetics of starch/AZC blends were investigated by using rheological measurements. The evolution of viscoelastic properties of AZC solutions and the AZC-starch blends was characterized. It was found that for both AZC self-crosslinking and AZC-starch co-crosslinking, the initial bond formation rate and the gel strength had a strong power law relationship with the concentrations of both AZC and starch. It is suggested that the development of the crosslinking network is highly dependent on the AZC concentration, while the starch concentration effect is less significant. It was determined that the activation energy of AZC self-crosslinking was approximately 145-151 kJ/mol, while the activation energy of AZC-starch co-crosslinking was 139 kJ/mol. (2) Fiber and filler modifications with starch and crosslinkers: Besides reacting with starch, AZC can react with cellulose which also contains hydroxyl groups. Theoretically, it is possible to use AZC as a crosslinker / coupling agent to graft starch onto cellulose fibers. It is believed that the grafted starch on fiber surfaces can improve the fiber bonding capability. In this thesis, a facile method to graft starch onto cellulose fiber surfaces through the hydrogen bond formation among cellulose, starch and AZC was developed. Compared with the paper sheets made of fibers with an industry refining level (420 ml CSF), the paper sheets made of fibers with a much lower refining degree but with grafted starch showed higher paper strengths, including the tensile strength, stiffness and z direction tensile; meanwhile, a faster drainage rate during web formation could also be achieved. Not only can the fiber-fiber bonding be improved by grafting starch onto fiber surfaces, but the filler-fiber bonding can also be improved if starch can be effectively coated on the filler surface. This concept has been supported by the early studies. In this thesis, the effects of the crosslinking of starch in the filler modification for the papermaking application were also studied. (3) Mechanism of starch nanoparticle formation during extrusion with crosslinkers: It was reported that starch crosslinking could facilitate the reduction of starch particle size during reactive extrusion. However, the mechanism of the particle size reduction by starch crosslinking was not illustrated. The reason that the crosslinking can cause the particle size reduction of starch during extrusion is fundamentally interesting. In this thesis, the mechanism of starch particle size reduction during extrusion with and without crosslinkers was investigated by identifying the contributions of thermal and mechanical effects. The effects of extrusion conditions, including temperature, screw speed, torque, starch water content and crosslinker addition, on the particle size were studied. It was found that the addition of crosslinkers could significantly increase the shear force (torque), and consequently facilitate the reduction of the particle size. The results indicate that for extrusion without a crosslinker, the starch particle size decreased with the increase of temperature. At 100 degree Celsius, the starch particles with a size of 300 nm could be obtained. With the addition of appropriate crosslinkers (glyoxal), the starch particle size could be reduced to around 160 nm, even at a lower extrusion temperature of 75 degree Celsius .

<p>The corrosion of current collector materials in MoltenCarbonate Fuel Cells (MCFC) is investigated. The essential aimsof this investigation were to study the corrosion behaviour ofdifferent materials, in varying cathode and anode MCFCenvironments, and to study the contact corrosion resistancesbetween the MCFC current collector and electrodes. For thesepurposes, pure iron, iron-chromium binary alloys and severalcommercial steels were investigated in molten carbonate meltswithin the pot-cell laboratory set-up. In addition, the contactcorrosion resistances, between an AISI 310 current collectorand two cathodes (NiO and LiCoO₂), were studied in a laboratory fuel cell.Post-tests were done to study the corrosion products formed atthe surfaces.</p><p>In cathode environments, corrosion potential increased overtime as a protective corrosion layer slowly formed. Eventually,the potential reached a stable value close to the cathodeoperating potential. The main cathode reaction, as corrosionpotential increased, changed from water reduction to oxygenreduction. Corrosion rate under the operating cathode conditiondepended on the chromium content; the higher the concentrationof chromium, the lower the corrosion rate. The corrosion ratesof ferritic steels, with high chromium content, and AISI 310were higher at the so-called outlet operating condition incomparison to the standard and so-called inlet conditions. Thecorrosion rate was higher at the beginning of the exposure,which resulted in a relatively fast corrosion layer growth thatslowed as the protective layer was formed. It was shown thatthe corrosion layers, formed on iron-chromium alloys, AISI 310and ferritic high chromium-containing steels, consisted of twolayers. The outer layer was porous and iron rich, while theinner layer was quite compact and rich in chromium and/oraluminiumTherefore, the corrosion behaviour was dependent onthe corrosion layer structure at the metal surface.</p><p>In anode environments, the beneficial behaviour of aluminiumin ferritic alloys, with high aluminium contents, was due tothe formation of aluminium oxide and/or lithium aluminium oxideat the surface. The corrosion rates at the standard and outletconditions were of the same order of magnitude, while thecorrosion rates at the inlet conditions were considerablyhigher. The lower temperatures and higher carbon dioxideconcentrations in the inlet conditions appeared to result in asurface layer deficient in aluminium. A modified theoreticalmodel was developed to evaluate the corrosion current densitiesfrom experimental polarisation curves or linear polarisationresistance measurements in anode environments. The fittingswere found to be very good.</p><p>An experimental method was developed for<i>in-situ</i>measurements of the contributions to the totalohmic losses at the cathode in a laboratory scale MCFC. Thecontact resistance between the cathode and current collectorcontributed quite a large value to the total cathodepolarization. The corrosion layer, formed between the LiCoO₂cathode and AISI 310 current collector, wasiron-rich and more porous, and contained a small amount ofcobalt. This was deemed to consist of a two-phase oxide, whichresulted in a lower conductivity. The corrosion layer, formedbetween the NiO cathode and AISI 310 current collector, wasrich in nickel. The corrosion layers on the AISI 310, incontact with the cathode, had a different composition comparedto samples immersed in carbonate melts.</p><p><b>Key words</b>: molten carbonate fuel cell (MCFC), corrosion,current collector, contact corrosion resistance.</p>

<p>Fuel cells are promising candidates for converting chemical energy into electrical energy. The Molten Carbonate Fuel Cell (MCFC) is a high temperature fuel cell that produces electrical energy from a variety of fuels containing hydrogen, hydrocarbons and carbon monoxide. Since the waste heat has a high temperature it can also be used leading to a high overall efficiency.</p><p>Material degradation and the cost of the components are the problems for the commercialisation of MCFC. Although there are companies around the world starting to commercialise MCFC some further cost reduction is needed before MCFC can be fully introduced at the market.</p><p>In this work, alternative materials for three different components of MCFC have been investigated. The alternative materials should have a lower cost compared to the state-of-the-art materials but also meet the life-time goal of MCFC, which is around 5 years. The nickel dissolution of the cathode is a problem and a cathode with lower solubility is needed. The dissolution of nickel for three alternative cathode materials was investigated, where one of the materials had a lower solubility than the state-of-the-art nickel oxide. This material was also tested in a cell and the electrochemical performance was found to be comparable with nickel oxide and is an interesting candidate.</p><p>An inexpensive anode current collector material is also desired. For the anode current collector, the contact resistance should be low and it should have good corrosion properties. The two alternative materials tested had low contact resistance, but some chromium enrichment was seen at the grain boundaries. This can lead to a decreased mechanical stability of the material. In the wet-seal area, the stainless steel used as bipolar/separator plate should be coated. An alternative process to coat the stainless steel, that is less expensive, was evaluated. This process can be a suitable process, but today, when the coating process is done manually there seems to be a problem with the adherence.</p><p>This work has been a part of the IRMATECH project, which was financed by the European Commission, where the partners have been universities, research institutes and companies around Europe.</p>

L'objectif de la thèse est d'élaborer de nouveaux matériaux polymères à hautes performances avec une porosité fermée de taille submicronique, selon une démarche originale de moussage par génération de gaz in-situ issu de la dégradation thermique de groupes pendants thermolabiles. <br />Après avoir choisi une matrice polymère thermostable de type poly(phénylquinoxaline)s (PPQ) et ayant sélectionné un groupement thermolabile (tertiobutylcarbonate, Boc), une étude sur molécules modèles a permis de définir précisément la démarche suivie dans ce travail. Le greffage de ces groupements thermolabiles sur des fonctions phénols a pu être validé. Enfin, la décomposition des groupements Boc (libération de CO2 et isobutène) s'est avérée très propre, totale et laissant présager un bon contrôle du processus de moussage du système PPQ + CO2/isobutène.<br />Différents monomères bis(Α-dicétone)s ont été synthétisés puis polymérisés avec une bis(o-diamine) commerciale, pour conduire à des PPQ portant des groupements phénoliques en chaîne latérale. Suivant les conditions expérimentales choisies, ont été réalisées des structures ayant des taux de fonctions phénols variables, et une répartition particulière de ces fonctions selon la nature du monomère ou des architectures "statistiques" ou "séquencées". Le greffage de fonctions carbonates sur ces phénols a permis d'accéder à des taux de gaz générés élevés et variant de 150 à 654 mg/g, avec une répartition directement reliée à celle des fonctions phénols initiales.<br />Trois paramètres essentiels permettent de contrôler les caractéristiques des matériaux poreux obtenus : la concentration en gaz généré, la Tg du polymère et la température de moussage.<br />L'utilisation de températures de moussage élevées a permis d'élaborer des mousses de PPQ macroporeuses (ultra- et microcellulaires) dont la morphologie est similaire aux matériaux obtenus par des procédés conventionnels au CO2 supercritique. Les caractéristiques de cette macroporosité peuvent être contrôlées en fonction de la concentration en gaz et de la Tg du polymère. <br />Par ailleurs, l'utilisation d'architectures "séquencées" (copolymères à blocs) permet la formation de matériaux ultra et microcellulaires ayant une double distribution de porosité. Cette distribution bimodale est très probablement due à une ségrégation de phase microscopique.<br />Des températures de moussage modérées ont permis, pour l'ensemble des polymères étudiés, la formation de matériaux nanocellulaires de porosité fermée. Ces résultats montrent donc qu'il est possible de former et de stabiliser des nano-cellules (8-40 nm) par un mécanisme de nucléation-croissance, dans une matrice polymère. L'obtention de tailles très faibles et de densités de cellules élevées, nécessite un taux de nucléation important (concentration en gaz élevée) et une faible croissance des nanocellules nucléées (viscosité du système élevée). Parmi les différentes structures étudiées, les mousses de PPQ-OH présentent le meilleur compromis entre une quantité de gaz importante (345 mg/g) et une Tg élevée (370 °C) et conduisent à des matériaux nanocellulaires particulièrement intéressants (taille: 8-11 nm – Nc: 4 1016 cellules/cm3 – P: 14-16 %vol).

Thesis (M. S.)--Materials Science and Engineering, Georgia Institute of Technology, 2005. / Committee Chair: Kenneth Sandhage; Committee Members: Joe Cochran, Robert Snyder and Tom Sanders. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1981. / Includes bibliographical references (p. 63-65).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1954. / Bibliography: leaves 108-109.

The distributions of calcite rich horizons within dryland soils are commonly used as paleoclimate proxies. Comprehensive conceptual and mathematical models of calcite accumulation in soils are required to accurately interpret and calibrate these proxies. A conceptual model for calcite accumulation is already well established: As water percolates through a soil, it dissolves minerals, such as calcite, transporting the soluble minerals downward. As soil water is removed by evaporation and transpiration, the water solution becomes supersaturated resulting in precipitation of calcite at depth. The impacts of dynamic plant growth and microbial respiration have not yet been simulated in numerical models for calcite accumulation but are likely important because of their influence on variables governing calcite solubility. The soil hydraulic modeling software, HYDRUS-1D, simulates water and solute transfer through a soil column, accounting for variations in all previously studied variables (temperature, water content, soil pCO₂) while additionally simulating vegetation-soil interactions. Five separate sensitivity studies were conducted to determine the importance for calcite accumulation of 1) soil texture, 2) plant growth, 3) plant phenology, 4) atmospheric CO₂ concentrations, and 5) the proximal variables that control calcite dissolution and precipitation: soil CO₂, soil water content, and soil temperature. In each modeling simulation, calcite was leached from the top several cm and redistributed deeper in the soil after 20 years. Soils with courser texture yield deeper (+20cm), more diffuse calcite horizons, as did simulations with bare soil compared to vegetated soil. The phenology of plant communities (late spring versus late summer growth) resulted in soil calcite accumulation at temperatures differing by at least 10°C. Changes in atmospheric CO₂ concentrations do not affect the soil calcite distribution. Variations in concentration of soil CO₂, rather than soil water content, have the greatest direct effect on calcite solubility. The most significant time periods of annual accumulation also corresponded with positive water fluxes resulting from high matric potential at the surface. Transpiration and evaporation moisture sinks caused solution to travel upward from higher to lower soil CO₂ concentrations, causing CO₂ de-gassing and calcite accumulation. This pathway describes a new qualitative mechanism for soil calcite formation and should be included in the conceptual model. / text

A limited number of laboratory studies and pilot programs have been reported in chemical Enhanced Oil Recovery (EOR) flooding of carbonate reservoirs (Adams & Schievelbein, 1987). Fewer still have involved surfactants in limestone reservoirs. No surfactant/polymer flood on a field wide basis of a carbonate reservoir has ever been documented in the literature (Manrique, Muci, & Gurfinkel, 2010). This void represents a colossal opportunity given that nearly a third of the 32 billion barrels of oil consumed in the world each year come from carbonate reservoirs (Sheng, 2011, pp. 1, 254). This thesis is based on experiments with a high hardness (~5,000 ppm divalent ions) carbonate field. Phase behavior, aqueous stability, and core flood experiments were performed using polymer and various surfactants and co-solvents. Both commercially available and laboratory synthesized surfactants were tested. The objective was to optimize the chemical injection design in order to lower interfacial tension between water and oil in the reservoir. Research was also done with alkali intended for use with hard brines. The main challenges when working with hard brine were poor solubilization and low aqueous stability limits. However, highly propoxylated and ethoxylated surfactants mixed with internal olefin sulfonates, hydrophilic sulfates, and sec-butanol were observed to have very high solubilization ratios, fast phase behavior equilibration times, negligible viscous macroemulsion effects, and excellent aqueous stability. Spinning drop interfacial tensiometer tests confirmed low IFT values were obtained for a range of acceptable salinities with hard brine. Three core floods were performed using one of the surfactant formulations developed. One flood was done with field core, brine, and crude oil and failed to meet expectations because of high levels of heterogeneity (vugs) within the core that lead to an elongated oil bank and low and slow oil recovery. The other floods were done with Estillades Limestone. The first Estillades flood used hard synthetic field brine and had better mobility but poor oil recovery. The last core flood had good mobility and recovered 90% of the residual oil to water flooding, but only after a total of 1.1 pore volumes of 1.0 wt% surfactant solution were injected. The results provided in this thesis constitute proof of concept that S/P flooding can be done in high salinity and hardness reservoirs. / text