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1
Oliveira, Mariana Salvim de. "Desenvolvimento e caracterização de micropartículas lipídicas sólidas carregadas com hidrolisado proteico obtidas por spray chilling." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/74/74132/tde-28012015-103020/.
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Hidrolisados proteicos possuem propriedades terapêuticas e são absorvidos mais facilmente pelo organismo quando comparados às proteínas, no entanto sua aplicação em alimentos é dificultada por serem higroscópicos, reativos e apresentarem gosto amargo. A microencapsulação por spray chilling pode ser uma alternativa para solucionar essas limitações. Este método de encapsulação consiste na atomização de uma mistura, formada pela dispersão ou emulsão do material ativo com o carreador fundido, em uma câmara com temperatura inferior ao ponto de fusão do carreador, que nessas condições solidifica, formando micropartículas esféricas. O objetivo deste trabalho foi elaborar micropartículas de hidrolisado de proteína de soja utilizando o método de spray chilling e gordura vegetal (PF 51°C) como carreador. Foram realizados ensaios para obtenção das micropartículas avaliando a alimentação por emulsão e dispersãoe diferentes formulações variando a proporção material ativo:encapsulante (1:5 e 1:10), velocidades de rotação no ultra-turrax (6000 e 8000 rpm) e três diferentes temperaturas (60, 70 e 80°C), totalizando dezoito tratamentos. As misturas foram submetidas à análise reológica para determinação de viscosidade e após serem atomizadas em spray chiller as micropartículas obtidas foram caracterizadas por FTIR, Difração de Raio-X, distribuição e tamanho médio por difração a laser e morfologia por microscopia eletrônica de varredura e confocal. Foram obtidas micropartículas lipídicas sólidas esféricas e aglomeradas, o tamanho médio variou de 53,06 ± 2,17 µm e 68,03 ± 14,07 µm, sem diferenças significativas entre os tratamentos. Partículas obtidas pela atomização da emulsão apresentaram poros, todavia exibiram maior capacidade de carregamento do hidrolisado, cerca de 96%, enquanto as obtidas por dispersão apresentaram 54%. Variações durante o preparo da emulsão não proporcionaram alterações na morfologia e tamanho de partícula nas micropartículas, apesar de terem tido influência sobre as propriedades reológicas do sistema. A análise de difração de raios-X indicou que as micropartículas após 90 dias de preparo apresentaram a estrutura na forma polimórfica mais estável. A espectroscopia na região do infravermelho (FTIR) revelou que não ocorreu interação entre os ingredientes independentemente do modo de preparo das micropartículas. Tais resultados demonstram que a técnica de spray chilling é eficiente na microencapsulação de hidrolisado proteico de soja, possibilitando uma futura aplicação em alimentos.<br>Protein hydrolysates possess therapeutic properties and absorption easier than to proteins; however its application in food is limited due to its bitter taste, hygroscopic and reactivity. Encapsulation byspray chilling could be an alternative to minimize these limitations. This method consists in the atomization of a mixture formed by the dispersion or emulsion of the active material with the molten carrier, into an environment with temperature below the melting point of the carrier, under these conditions it solidifies to form spherical microparticles. The aim of this work was to develop microparticles loaded with hydrolyzed soy protein using the method of spray chilling and vegetable fat (PF 51°C) as carrier. Tests were conducted to obtain microparticles evaluating the feed by emulsion and dispersion and different formulations by varying the proportions active materials:carrier (1:5 and 1:10), homogenization speed by Ultra-Turrax (6000 and 8000 rpm) and temperature (60, 70 and 80°C ), totaling eighteen treatments. The mixtures were subjected to rheological analysis for determination of viscosity and after being atomized at spray chiller obtained microparticles were characterized by infrared spectroscopy and X-ray diffraction, particle size distribution and mean diameter measured using a laser light diffraction instrument and morphology was observed by scanning electron microscopy (SEM) and confocal microscopy. Solid lipid microparticles obtained were spherical and agglomerated the average size between 53.06 ± 2.17 µm and 68.03 ± 14.07 µm, there was no significant difference between formulations. Particles obtained by atomization of emulsion had presence of pores, but exhibited a higher loading capacity of the hydrolyzed, about 96%, while that obtained by dispersion had 54%. Changes during the preparation of the emulsion no provided changes at morphology and particle size of the microparticles, despite having influence on the rheological properties of the system. The analysis of X-ray diffraction showed that the microparticles after 90 days of storage had β polymorphic form. The infrared spectroscopy (FTIR) showed that there was no interaction between the ingredients regardless of the mode of preparation of the microparticles. These results demonstrate that the technique spray chilling is efficient in microencapsulation of soy protein hydrolyzate, allowing future use in foods.
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Miyagawa, Yayoi. "Analysis of factors affecting dispersion stability of O/W emulsion during freezing and thawing processes." Kyoto University, 2018. http://hdl.handle.net/2433/232339.
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Cauvin, Séverine. "Polymérisation cationique du p-méthoxystyrène en dispersion aqueuse en présence de triflate d'ytterbium." Paris 6, 2003. http://www.theses.fr/2003PA066416.
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Rajapakse, Achula, and s9508428@student rmit edu au. "Drop size distribution and interfacial area in reactive liquid-liquid dispersion." RMIT University. Civil Environmental and Chemical Engineering, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080717.163619.
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Emulsion explosives have become the preferred choice as blasting agents for numerous industries including mining, agriculture, and construction. One of the most important components in such an emulsion is an emulsifier, which controls the emulsification properties of the explosive. The present study involves the production of one such emulsifier, which is produced by reacting two immiscible liquids, PIBSA (polyisobutylene succinic anhydride) and MEA (monoethanolamine). The study examines the effect of design variable such as the impeller speed, impeller type and the dispersed phase volume fraction on interfacial area. Experiments were carried out in a 0.15 m diameter fully baffled stirred tank using a 6-bladed Rushton turbine impeller and a marine propeller. Drop size was determined using a microscope with a video camera and image processing system. The transient concentration of PIBSA was determined using FTIR analysis and used to estimate the volume fraction of the dispersed phase (Ö). The effective interfacial area was calculated using the Sauter mean drop diameter, d32 and Ö. Impeller speeds ranging from 150 to 600 rpm and dispersed phase volume fractions, Ö ranging from 0.01 to 0.028 were examined in the experimental study. It was found that that the evolution of Sauter mean drop diameter, d32 has four different trends depending on Ö and impeller speed. At high impeller speeds and high Ö, d32 values decrease initially and reach constant values after a long period of time. This trend is consistent with the findings in previous investigations. Under certain operating conditions, d32 values increase initially with stirring time to reach a maximum value and then decrease to reach a steady state value. The presence of these trends has been attributed to the effect of changing physical properties of the system as a result of chemical reaction. Results indicate that, in general, Sauter mean drop diameter d32 decreases with an increase in agitation intensity. However a decrease in the dispersed phase volume fraction is found to increase d32. These trends are found to be the same for both impeller types studied. Comparing the drop size results produced by the two impellers, it appears that low-power number propeller produces s ignificantly smaller drops than the Rushton turbine. It was found that the concentrations of reactants decrease with time for all impeller speeds thereby leading to a decrease in interfacial area with the progress of the reaction. Interfacial area values obtained at higher impeller speeds are found to be lower in spite of lower d32 values at these speeds. Also, these values decrease with time and become zero in a shorter duration indicating the rapid depletion of MEA. The interfacial area values obtained with the propeller at a given impeller speed are lower as compared to those for Rushton turbine. They also decrease and become zero in a shorter duration as compared to those for Rushton turbine suggesting propeller¡¦s performance is better in enhancing the reaction rate.
5
Nguyen, David. "Etude de la nucléation contrôlée de latex polymère à la surface de nanoparticules d’oxyde pour l’élaboration de colloïdes hybrides structurés." Thesis, Bordeaux 1, 2008. http://www.theses.fr/2008BOR13715/document.
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Des colloïdes à base de silice et de polystyrène ont été synthétisés. Les particules d’oxyde ont d’abord été élaborées et modifiées en surface, puis ont servi de germes au cours d’une étape de polymérisation du styrène. Deux procédés de polymérisation en phase hétérogène ont été utilisés (émulsion ou dispersion) menant à des colloïdes aux morphologies originales et contrôlées. Une étude morphologique par tomographie électronique a permis de mieux comprendre les mécanismes de croissance et d’organisation des particules de latex autour des germes de silice. La synthèse de particules Janus pour l’imagerie biomédicale est aussi décrite. Ces particules de silice ont été modifiées en surface par un chromophore biphotonique et un agent de reconnaissance de certaines cellules tumorales. Des études spectroscopiques et des tests de cytotoxicité ont été entrepris<br>Hybrid colloids based on silica and polystyrene have been synthesized. Oxide particles were first elaborated, surface modified, and then used as seed in a styrene polymerization step. Two heterogeneous polymerisation proceeds were employed (emulsion or dispersion) leading to colloids with original and controlled morphologies. A morphological study by electronic tomography enabled to better understand growth and organisation mechanisms of latexes around silica seeds. Janus particles synthesis for biomedical imaging is also described. Silica particles were surface modified with a biphotonic chromophore and a tumor cells targeting agent. Spectroscopic studies and cytotoxicity tests were investigated
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Russum, James. "Controlled Radical Polymerizations in Miniemulsions: Advances in the Use of RAFT." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-10112005-105314/.
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Thesis (Ph. D.)--Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2006.<br>Jones, Christopher, Committee Chair ; Schork, F. Joseph, Committee Co-Chair ; Weck, Marcus, Committee Member ; Meredith, Carson, Committee Member ; Agrawal, Pradeep, Committee Member.
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Lattaud, Cecile. "Synthesis of low density foam shells for inertial confinement fusion experiments." Thesis, Dijon, 2011. http://www.theses.fr/2011DIJOS033/document.
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Ce travail porte sur le processus de fabrication de microballons en mousse basse densité et le contrôle fin de leur forme (diamètre, épaisseur, densité, sphéricité, non-concentricité). Durant cette thèse nous nous sommes concentrés sur le critère de non-concentricité qui doit être inférieure à 1%. Les microballons sont synthétisés en utilisant un procédé de microencapsulation conduisant à une émulsion double, suivie d'une polymérisation thermique à 60°C. Selon la littérature, trois paramètres majeurs, la densité des trois phases, les déformations du microballon pendant le procédé et la cinétique de polymérisation ont une influence directe sur la non-concentricité des microballons. Les résultats obtenus ont montré que lorsque l'écart de densité entre la phase aqueuse interne et la phase organique augmente, la non-concentricité des microballons TMPTMA s'améliore. Un écart de densité de 0,078 g.cm-3 à 60°C conduit à une non-concentricité moyenne de 2,4% avec un rendement en microballons de 58%. Il a également été montré que la synthèse peut être considérée comme reproductible. Pour une même phase aqueuse interne, les résultats de non-concentricité sont équivalents en utilisant soit un tube droit, un tube à étranglement ou un serpentin court. Le temps requis pour fixer la forme des microballons est d'au moins 20 minutes avec la polymérisation thermique. Ainsi, il semble que le temps passé par les microballons à l'intérieur des bouteilles de réception permet le centrage de la phase aqueuse interne à l'intérieur de la phase organique, quel que soit le processus de circulation précédemment utilisé. Afin d'obtenir des vitesses de polymérisation plus élevées et d'éviter les phénomènes de déstabilisation, nous avons alors concentré notre étude sur la photopolymérisation. Lorsque la synthèse est effectuée en utilisant une lampe UV avec une intensité lumineuse efficace, les microballons ont une épaisseur légèrement supérieure à celle des microballons synthétisés par voie thermique. Par ailleurs, un rendement plus élevé, environ 80%, est obtenu avec la polymérisation UV. Toutefois, la non-concentricité moyenne des microballons synthétisés est environ de 20%, ce qui est vraiment élevé par rapport à la non-concentricité moyenne de 2,4% obtenue par polymérisation thermique. Il serait intéressant d'exposer les microballons à la lumière UV, à différents moments après la collecte afin d'étudier l'influence du temps d'agitation sur la non-concentricité des microballons<br>This work deals with the fabrication process of low density foam shells and the sharp control of their shape (diameter, thickness, density, sphericity, non-concentricity). During this PhD we focused on the non-concentricity criterion which has to be lower than 1%. The shells are synthesized using a microencapsulation process leading to a double emulsion and followed by a thermal polymerization at 60°C. According to the literature, three major parameters, the density of the three phases, the deformations of the shells along the process and the kinetics of the polymerization have a direct influence on the shells non-concentricity. The results obtained showed that when the density gap between the internal water phase and the organic phase increases, the TMPTMA shells non-concentricity improves. A density gap of 0.078 g.cm-3 at 60°C, leads to an average non-concentricity of 2.4% with a yield of shells of 58%. It was also shown that the synthesis process can be considered as reproducible. While using the same internal water phase, equivalent non-concentricity results are obtained using either a straight tube, a tube with areas of constriction or a short wound tube. The time required to fix the shell’s shape is at least 20 minutes with thermal polymerization. So, it seems that the time spent by the shells inside the rotating flask allows the centering of the internal water phase inside the organic phase, whatever the circulation process used. In order to get higher polymerization rates and to avoid destabilization phenomena, we then focused our study on photopolymerization. When the synthesis is performed using a UV lamp with an efficient light intensity, the shells have a slightly higher thickness than the shells synthesized by thermal polymerization. Moreover, a really higher yield, around 80%, is achieved with UV polymerization. However, the average non-concentricity of the shells synthesized lays around 20%, which is really high compared to the 2.4% average non-concentricity obtained with thermal polymerization. It would be interesting to expose the shells to UV light at different times after collection in order to study the influence of the agitation time on the shells non-concentricity
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ATTIA, MONDHER. "Etude experimentale de la dispersion anormale de la photoanisotropie induite dans les emulsions de chlorure d'argent." Paris 6, 1986. http://www.theses.fr/1986PA066671.
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Spectres de dichroisme et de birefringence induits par un faisceau de lumiere rectilignement polarise. Modele decrivant la composition de l'emulsion anisotrope et donnant une expression analytique du dichroisme et de la birefringence. Calcul de l'efficacite de diffraction des reseaux anisotropes enregistres sur une telle emulsion
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Kibboua, Rachid. "Etude d'une dispersion liquide-liquide soumise à un écoulement cisaillé simple : caractérisation vis à vis de la coalescence." Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10167.
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L'ecoulement d'une dispersion eau-huile a ete analyse experimentalement et theoriquement pour differentes huiles dans le cas d'un ecoulement de couette circulaire. Les mesures locales effectuees ont porte sur le profil radial de concentration des gouttes par imagerie dans le cas ou l'un ou l'autre des deux cylindres est tournant. D'autres mesures globales ont ete faites et portent sur la mesure du diametre de sauter de la population de gouttes par attenuation lumineuse a l'aide d'une sonde optique. Un modele de melange a ete etabli pour la prediction du profil radial de concentration. Ce modele nous a permis de degager une relation empirique de la diffusivite hydrodynamique. D'autre part les mesures du diametre de sauter ont permis d'estimer le taux de coalescence dans une dispersion eau-huile par confrontation des mesures avec une equation de bilan de population
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Cerino, Clelio. "Ιntensificatiοn de la séparatiοn d'émulsiοns par chauffage micrο-οndes : applicatiοn à l'extractiοn liquide-liquide de métaux critiques". Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMIR16.
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Cette thèse s’attache à étudier l’application d’une méthode d’intensification de la séparation des phases d’une émulsion par chauffage micro-ondes aux émulsions typiques rencontrées en extraction liquide-liquide pour la récupération de métaux critiques. Après une revue de la littérature concernant la séparation de telles émulsions, le traitement / chauffage par micro-ondes, puis le point spécifique de l’intensification de la séparation d’émulsions (typiquement pétrolières) par chauffage micro-ondes, le travail de thèse se centre sur quatre parties : Dans un premier temps, les propriétés physico-chimiques pertinentes pour la séparation de phase et identifiées dans l’étude bibliographique sont mesurées, ainsi que leur évolution avec la température. Les mesures de tension interfaciale, ainsi que les essais préliminaires de séparation, font ressortir le rôle déterminant mais mal compris de la tension interfaciale et de son évolution temporelle. Ensuite, on mesure et modélise, à partir de modèles issus de la littérature, les permittivités des phases liquides et des émulsions, grandeur d’intérêt pour décrire la propagation des ondes électromagnétiques dans ces matières, et permettant notamment de prévoir les longueurs de pénétration des micro-ondes dans les différentes matières. Les permittivités mesurées justifient le développement et l’emploi d’un séparateur continu intensifié par micro-ondes, à échelle laboratoire, afin d’observer à de faibles échelles de tailles et de débits l’influence des micro-ondes sur la séparation des émulsions. En dernier point, on entreprend une étude, par des simulations grâce au logiciel COMSOL Multiphysics, de la répartition de la puissance micro-ondes dans les matières à traiter, dans la géométrie expérimentale précédemment évoquée, ainsi que dans des géométries simplifiées afin de mettre en évidence les possibles problèmes à venir si une industrialisation est envisagée. Les résultats obtenus avec le séparateur mis en œuvre lors du travail de thèse, ainsi que les simulations effectuées, permettent effectivement de valider l’intérêt de la méthode, ainsi que d’envisager la mise à échelle industrielle. Les annexes présentent des axes de recherche identifiés au cours de la thèse<br>This thesis focuses on the application of a microwave heating emulsion separation method to the phase separation of emulsion typical to the critical metal recovery processes. Following a literature review centered around emulsion separation, microwave heating in general, and the intensification of the separation of petroleum-based emulsions by microwave heating, the research work focuses firstly on physico-chemical properties relevant to the phase separation of the studied emulsions, and their evolution with temperature. Surface tension measurements, along with preliminary separation tests, show the important but hardly understood role of surface tension and its time evolution. Emulsion and single phase permittivities are then measured and modeled with equations available in the literature, allowing us to prefigure the penetration depth achievable in such materials with microwaves. The measured permittivities justify employing a laboratory scale, microwave intensified phase separator to observe, with small treatment volume and fluids throughput, the effect of microwaves on emulsion separation. Lastly, we study microwave heating numerically, with COMSOL Multiphysics, first with the aforementioned experimental geometry, then with simpler geometries, presenting problems that could arise, should an industrialization occur. Results obtained with the experimental set-up, as well as the simulations performed allow us to confirm the described method’s interest in the metal recovery context, and to prefigure scale-up. The annexes present further research axis identified during the thesis
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Nguyen, David. "Etude de la nucléation contrôlée de latex polymère à la surface de nanoparticules d'oxyde pour l'élaboration de colloïdes hybrides structurés." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2008. http://tel.archives-ouvertes.fr/tel-00384507.
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Des colloïdes à base de silice et de polystyrène ont été synthétisés. Les particules d'oxyde ont d'abord été élaborées et modifiées en surface, puis ont servi de germes au cours d'une étape de polymérisation du styrène. Deux procédés de polymérisation en phase hétérogène ont été utilisés (émulsion ou dispersion) menant à des colloïdes aux morphologies originales et contrôlées. Une étude morphologique par tomographie électronique a permis de mieux comprendre les mécanismes de croissance et d'organisation des particules de latex autour des germes de silice. <br />La synthèse de particules Janus pour l'imagerie biomédicale est aussi décrite. Ces particules de silice ont été modifiées en surface par un chromophore biphotonique et un agent de reconnaissance de certaines cellules tumorales. Des études spectroscopiques et des tests de cytotoxicité ont été entrepris.
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Delaittre, Guillaume. "Polymérisation radicalaire contrôlée en émulsion et dispersion sans tensioactif : synthèse de nanoparticules thermo- et/ou pH-sensibles." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00277445.
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Une macroalcoxyamine hydrosoluble (poly(acide acrylique) fonctionnalisé par le nitroxyde SG1) a été utilisée avec succès en polymérisation radicalaire contrôlée en milieux aqueux dispersés. En émulsion, des latex de poly(acrylate de n-butyle), de polystyrène et de copolymères correspondants ont pu être obtenus pour la première fois selon un procédé émulsion batch ab initio, procédé le plus viable industriellement. Le mode opératoire ne requiert pas l'utilisation de tensioactifs classiques. Des particules de copolymères dibloc à cœur hydrophobe et écorce polyélectrolyte avec un diamètre moyen compris entre 30 et 100 nm sont synthétisées au sein de suspensions pouvant atteindre des taux de solide de 40 wt.%. Les masses molaires et les indices de polymolécularité révèlent le caractère contrôlé de la polymérisation en dépit d'une efficacité d'amorçage déficiente. Différents paramètres permettant de modifier les masses molaires des polymères et la taille des particules ont été mis en évidence. Le mécanisme de formation des particules est discuté ainsi que la cinétique de polymérisation dans les particules. En dispersion, des particules de poly(N,N-diéthylacrylamide) dissociables thermiquement et réversiblement ont été synthétisées avec des caractéristiques macromoléculaires et colloïdales proches de celles obtenues en émulsion et ce, jusqu'à 40 wt.% de taux de solide. Par l'introduction d'un monomère réticulant selon un procédé batch ou semi-batch, des nanogels thermosensibles sont produits. Ce résultat constitue une avancée majeure dans ce domaine puisque, pour la première fois, une suspension concentrée de nanogels de faibles diamètres a pu être obtenue sans tensioactif.
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Raffy, Simon. "Synthèse de métamatériaux acoustiques par voie microfluidique." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0135/document.
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Ces travaux sont consacrés à la synthèse d'un nouveau type de métamatériaux acoustiques dans le domaine ultrasonore. L'étude porte sur les résonances de cavité, elles peuvent influer sur les différentes grandeurs physiques impliquées dans la propagation des ondes acoustiques. Pour amplifier les résonances, la stratégie a été de mettre en place un contraste de vitesse de phase entre la matrice et les inclusions résonantes. Pour travailler dans le domaine ultrasonore, les techniques de mise en oeuvre sont issues de la microfluidique. Les premiers échantillons sont élaborés par émulsification micrométrique assistée par robotique. Cela permet d'obtenir des polydispersités de l'ordre de 1%. Différents modes de résonances acoustiques ont ainsi été observés. Les recherches ont été poussées jusqu'à l'étude de la polydispersité (1 à 12 %) et l'analyse de systèmes comprenant deux populations de gouttes. Le reste du travail s'est fait en millifluidique avec la mise en forme de dispersions de billes de xérogel de silice avec de plus importants contrastes de vitesse. La synthèse utilisée est une réaction de type sol-gel en milieu basique salin. Le montage millifluidique a été mis en place et calibré pour cette synthèse. La réaction chimique et les particules obtenues ont été caractérisées de nombreuses manières (Raman, rhéologie, mesure de compression, de densité, BET, MEB...). Les mesures acoustiques sur de tels systèmes ont permis de mettre en évidence des gammes de fréquence pour lesquelles l'indice de réfraction acoustique était négatif les plus fortes fractions volumiques (≈ 20%)<br>This work is dedicated to the synthesis of a new kind of acoustic metamaterials working in the ultrasonic range. The study is based on cavity resonance which can influence physical quantities involved in acoustic wave propagation. For amplifying these resonances, a large phase velocity contrast is required between the matrix and the inclusions.For the ultrasonic range and because of size requirements, the implementation is achieved using microfluidics. First, samples are generated using robotic-assisted emulsification which leads to a very small size polydispersity, around 1%. For these calibrated emulsions, different modes of acoustic resonance are clearly identified. We then generated polydisperse samples on purpose (up to 12%) and correlated the quality factor of the resonances to the size dispersity. Then, in order to enhance the resonance magnitude, silica-based xerogels are synthesized and templated using digital millifluidics. The chemical reaction along with the final xerogel micro-beads (≈ 100 μm radius) are characterized with a large variety of techniques (Raman, rheology, compression and density measurement, BET, SEM...). Acoustic measurements on these systems show that there is a frequency range with a negative acoustic refractive index for a at high enough volume fraction of xerogel particles (20%)
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Lattaud, Cécile. "Synthesis of low density foam shells for inertial confinement fusion experiments." Phd thesis, Université de Bourgogne, 2011. http://tel.archives-ouvertes.fr/tel-00692058.
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This work deals with the fabrication process of low density foam shells and the sharp control of their shape (diameter, thickness, density, sphericity, non-concentricity). During this PhD we focused on the non-concentricity criterion which has to be lower than 1%. The shells are synthesized using a microencapsulation process leading to a double emulsion and followed by a thermal polymerization at 60°C. According to the literature, three major parameters, the density of the three phases, the deformations of the shells along the process and the kinetics of the polymerization have a direct influence on the shells non-concentricity. The results obtained showed that when the density gap between the internal water phase and the organic phase increases, the TMPTMA shells non-concentricity improves. A density gap of 0.078 g.cm-3 at 60°C, leads to an average non-concentricity of 2.4% with a yield of shells of 58%. It was also shown that the synthesis process can be considered as reproducible. While using the same internal water phase, equivalent non-concentricity results are obtained using either a straight tube, a tube with areas of constriction or a short wound tube. The time required to fix the shell's shape is at least 20 minutes with thermal polymerization. So, it seems that the time spent by the shells inside the rotating flask allows the centering of the internal water phase inside the organic phase, whatever the circulation process used. In order to get higher polymerization rates and to avoid destabilization phenomena, we then focused our study on photopolymerization. When the synthesis is performed using a UV lamp with an efficient light intensity, the shells have a slightly higher thickness than the shells synthesized by thermal polymerization. Moreover, a really higher yield, around 80%, is achieved with UV polymerization. However, the average non-concentricity of the shells synthesized lays around 20%, which is really high compared to the 2.4% average non-concentricity obtained with thermal polymerization. It would be interesting to expose the shells to UV light at different times after collection in order to study the influence of the agitation time on the shells non-concentricity.
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Hughes, Roy Wesley. "The microrheology of emulsions." Thesis, University of Bristol, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277635.
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Stark and Holger. "Physics of Inhomogeneous Nematic Liquid Crystals: Colloidal Dispersions." Thesis, Universitaet Stuttgart, 1999. http://elib.uni-stuttgart.de/opus/volltexte/2001/746/index.html.
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Moraes, Cristhianne Soares Silva. "Desenvolvimento de sistemas dispersos a partir do óleo das sementes de baru (Dipteryx alata Vog.)." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/60/60137/tde-03102016-144704/.
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Um dos veículos de grande utilização para ativos cosméticos são os sistemas emulsionados, que são constituídos de duas fases líquidas imiscíveis e agentes tensoativos, obtidos por diferentes metodologias de emulsificação. Devido à sua excelente capacidade de solubilizar compostos hidrofílicos e lipofílicos a importância comercial e científica das emulsões entre os diversos sistemas coloidais é inquestionável. O delineamento desses sistemas exige conhecimento dos principais fatores que influenciam sua formação, propriedades físico-químicas e, consequentemente, estabilidade e performance. O uso de óleos vegetais na iensdpúésctrieias vfaergmeataciês uotliecaa gien ocsoassm, péotidcae mtoosrn cai-taser oc baadrau (vDeizp temryaxis a laattraa tVivoog. .)D, neanttirvea daos Bioma Cerrado e cujas sementes contêm um óleo com alto grau de insaturação cseonntdeor qousa nátcididaodse sg rsaixgonsif icoalenitceos teo cloinfoelreóiicso e ofsit oceosntesrtóituisi,n treesp rmesaejonrtaitánrdioos i,m aploérmta ndtee fonte de agentes capazes de atuar no combate aos processos oxidativos diretamente ligados ao envelhecimento e às doenças degenerativas. O objetivo duteilsiztaa npdeos cqoumisao ffaosi eo o ldeeossean ovo ólvleimoe enxtotr aeíd oc adraasc tesreimzaeçnãtoe s ddee sbisatreum (aDs. adliastpae).r sAoss etapas envolvidas no desenvolvimento dos sistemas estão listadas a seguir: 1) Obtenção e caracterização da matéria prima vegetal (óleo); 2) Desenvolvimento das fboarrmu u(lDaç. õaelas:t ae);s teusdtou ddoo dEaq culialísbsrieo dHeid treónfisloo aLtiivpoósfi;l oc o(EnHstLru) çrãeoq udeor iddoia gpraarma ao tóelrenoá rdioe; coabrtaidcotes;r iz3a) çEãnos afíiosisc oin-q vuiítmroi:c aA vea liaeçsãtuod doas s dme uedsatnaçbailsid easdteru tduoras iss mistiecrmoascsó pdiicsapse rdsooss sistemas dispersos mediante simulação da evaporação do produto final após aplicação na pele; estudo do efeito dos sistemas dispersos na dinâmica da membrana de estrato córneo por Ressonância Paramagnética Eletrônica. Os resultados encontrados sugerem que os sistemas dispersos desenvolvidos são potenciais alternativas na liberação de fármacos ou ativos cosméticos ou ainda, podem ser considerados produtos finais de interesse para recuperação da camada lipídica da pele. O uso de metodologia de emulsificação com baixo gasto de energia (emulsificação por inversão de fases) permitiu a obtenção de dois sistemas emulsionados estáveis: um com presença de fase gel lamelar e outro com partículas de tamanho nanométrico. O estudo das propriedades físico-químicas das formulações mostrou inexistência de quaisquer sinais de instabilidade das formulações durante o período de armazenamento em condições de temperatura específicas. A utilização de espectroscopia de Ressonância Paramagnética Eletrônica (RPE) forneceu informações acerca da dinâmica molecular do estrato córneo frente a aplicação do óleo e das formulações, demonstrando o potencial dos mesmos em atuar como veículos de fármacos ou ativos cosméticos visto que os espectros obtidos revelaram diferenças significativas na fluidez dos lipídios do estrato córneo, principal barreira na permeação cutânea.<br>The commercial and scientific importance of emulsions among the colloidal systems is unquestionable. These systems consist of two immiscible phases that could be obtained by different methods of emulsification. Emulsions have excellent ability to solubilize hydrophilic and lipophilic compounds, so, are widely used as vehicules for drugs and cosmetics. The rational design of these systems requires studies of the main factors that influence their formation, physicochemical properties and, consequently, stability and performance. Nowadays, the use of vegetable oils in the pharmaceutical and cosmetic industries becomes attractive. Dipteryx alata Vog is an oleaginous plant specie native to Cerrado. The seeds of this specie contain an oil with a high degree of unsaturation (oleic and linoleic fatty acids are the major constituents) and significant amounts of tocopherols and phytosterols, representing an important source of agents capable of acting to combat the oxidative processes directly related to aging and degenerative diseases. The objective of this research was the development and characterization of dispersed systems using the oil extracted from the seeds of D. alata (baru). The steps involved in the development of the systems were: 1) Preparation and characterization of vegetable raw material (oil); 2) Development of formulations: Study of Hydrophilic and Lipophilic Balance (HLB) required for baru oil; study of surfactant class; Construction of the ternary diagram; physicochemical characterization and stability studies of dispersed systems obtained; 3) In vitro assays: Evaluation of microscopic structural change of dispersed systems by simulating the evaporation of the final product after application on the skin; study of the effect of dispersed systems in the dynamics of the stratum corneum membrane by Electron Paramagnetic Resonance. The use of low energy emulsification method allowed the development of two stable emulsions: one with presence of lamellar gel phase and another with nanometric size particles. The study of physicochemical properties of the formulations showed absence of any signs of instability of the formulations during the storage period. The use of Electron Paramagnetic Resonance (EPR) spectroscopy provide information about the molecular dynamics of the stratum corneum facing the implementation of oil and formulations, demonstrating the potential of them to act as drug or cosmetic active vehicles
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Johnson, Andrew James. "Membrane permeation from solutions, particle dispersions and particle-stabilised emulsions." Thesis, University of Hull, 2013. http://hydra.hull.ac.uk/resources/hull:7110.
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This thesis is primarily concerned with understanding how the rate and extent of membrane permeation of a drug is affected by switching the donor delivery vehicle for different permeants and membranes. The project is funded by an industrial Collaborative Awards in Science and Engineering (CASE) award with an additional sponsorship by GlaxoSmithKline (GSK). The interest of GSK in this research is in the understanding of how the various types of topical formulation available, such as solutions, ointments, dispersions and emulsions, influence the characteristics of drug transport across a membrane. The rate and extent of membrane permeation from various types of topical formulation is experimentally investigated through the use of a developed automated method which is shown to be accurate and highly reproducible. The developed method incorporates stirred donor and re-circulating receiver compartments and continuous monitoring of the permeant concentration in the receiver phase. In a theoretical model based on rate-limiting membrane diffusion, an explicit set of equations are derived showing how the permeation extent and rate depend mainly on the membrane-donor and membrane-receiver partition coefficients of the permeant. The permeation of drug molecules from simple, single phase donor solutions are first investigated. The experimental permeation results for systems containing all possible combinations of hydrophilic or hydrophobic donor solvent, permeant and polymer membrane are measured using the developed method and are then compared to the calculated theoretical results. A quantitative comparison of model and experimental results from the widely-differing permeation systems successfully enables the systematic elucidation of all possible donor solvent effects in membrane permeation. For the experimental conditions used here, most of the permeation systems are in agreement with the model, demonstrating that the model assumptions are valid. In these cases, the dominant donor solvent effects arise from changes in the relative affinities of the permeant for the donor and receiver solvents and the membrane and are quantitatively predicted using the separately measured partition coefficients. It is also shown how additional donor solvent effects can arise when switching the donor solvent causes one or more of the model assumptions to be invalid. These effects include a change in rate-limiting step, permeant solution non-ideality and others. The development of a new type of formulation is investigated whereby the preparation of waterless, particle-stabilised emulsions is reported upon. The prepared emulsions incorporate a non-aqueous polar liquid phase, an immiscible oil phase and are stabilised by solid nanoparticles. Variation of the incorporated oil, polar liquid and particle hydrophobicity allow for the preparation of stable emulsions containing a wide range of liquids of both oil-in-polar liquid and polar liquid-in-oil emulsion types. The prepared formulations show great potential as vehicles for use in drug delivery in the pharmaceutical industry. These waterless emulsions provide several advantages such as high emulsion stability, aesthetic textures for topical application, aesthetic appearances (including the preparation of transparent emulsions through matching of the refractive index of the liquid phases) and the capability of containing very high hydrophobic drug concentrations dissolved within due to the absence of an aqueous liquid phase. The permeation of a drug molecule from more complex multiphase donor formulations, such as particle dispersions and particle stabilised emulsions, is also investigated. The delivery of a permeant across a synthetic membrane from both conventional oil-water and the developed waterless emulsions is discussed. The same experimental technique as that used to investigate the membrane permeation from single phase donor solutions is employed and a comparison of the experimental results to those calculated using the derived theoretical model is given. The theoretical model is adapted to account for the additional partioning of the permeant between the multiple phases present in these more complex donor formulations, but maintains the same set of underlying assumptions and fundamental principles of diffusion. The model successfully accounts for the experimental observations and reveals information regarding the mechanism of drug delivery from particle-stabilised emulsions. It is conclusively illustrated that permeant delivery from particle-stabilised emulsions occurs via partitioning of the drug between the dispersed and continuous emulsion phases prior to partitioning to the membrane exclusively from the emulsion continuous phase (i.e. dispersed emulsion droplet adhesion onto the surface of the membrane does not occur). Through analysis of the derived theoretical model, the extent and rate of membrane permeation of a permeant are correctly predicted to be independent of the emulsion type (i.e. oil-in-water or water-in-oil) and emulsion dispersed volume fraction for a given emulsion composition.
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Shastry, Vineet. "Identification Of The Nucleation Locus In Emulsion Polymerization Processes." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000221.
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Vicic, Michael Brady John F. "Rheology and microstructure of complex fluids : dispersions, emulsions and polymer solutions /." Diss., Pasadena, Calif. : California Institute of Technology, 1999. http://resolver.caltech.edu/CaltechETD:etd-04072005-160903.
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Stark, Holger. "Physics of inhomogeneous nematic liquid crystals colloidal dispersions and multiple scattering of light /." [S.l. : s.n.], 1999. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8921083.
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Romand, Alison. "Mise en émulsion sans tensioactif de résines alkydes et formulation de peintures biosourcées." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1016.
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Les peintures sont omniprésentes dans nos civilisations modernes et décorent presque tous les supports et ce dans des domaines très variés. L'utilisation massive des peintures pose cependant des problèmes environnementaux et de santé publique, de par la présence de solvants qui, lors du séchage, s'évaporent et émettent des composés organiques volatiles (COV) néfastes pour l'environnement et l'homme. Une démarche européenne et mondiale de réduction d'émission des COV est donc en cours depuis quelques années. De plus, l'engouement croissant pour le développement durable pousse à la transition de produits pétrosourcés vers des produits biosourcés, à coûts et performances similaires. Les résines alkydes en émulsions, développées au début du XXème siècle, constituent une alternative de choix car émettant une quantité limitée de COV et obtenues par polycondensation de matières premières renouvelables. Après un état de l'art sur le contexte des peintures actuelles et la composition d'une peinture alkyde en émulsion, leurs propriétés physiques et chimiques ont été étudiées. Après ce travail de formulation, deux additifs ont été synthétisés afin d'augmenter le taux de biosourcé des peintures alkydes en émulsion : un épaississant et un agent dispersant. De par la présence de surfactants, les formules de peintures alkydes en émulsion sont pour l'heure moins compétitives que les peintures alkydes en phase solvant. En conséquence, la première émulsion alkyde sans tensioactif a été développée et ses performances évaluées en peinture<br>Paints and coatings occupy a prominent place in the cultural history of mankind. People have always been fascinated by colors and used paints to decorate and beautify themselves and their environment. Nevertheless, these products bring a lot of problems. For instance, some paints still contain organic solvents, which have negative impacts on the environment and human health. Due to environmental legislations and the need to reduce VOCs emission (volatile organic compounds), water-based paints have attracted a lot of interest. Moreover, the raising sustainability awareness is a driving force for the transition from petrobased to biobased products with equivalent costs and performances. In this context, alkyd resin emulsion, introduced in the 1990s, still continue to be the most widely used binder, because they have low VOCs level and are synthesized by polycondensation reactions of renewable raw materials. After reviewing the current state of the art regarding the alkyd paint emulsion, their physical and chemical properties were studied. Two additives, respectively a rheology modifier and a dispersing agent, were also synthesized, in order to increase the biobased content of alkyd paint emulsion Due to the presence of wetting agent, alkyd emulsion paints are still less competitive than solvent-borne alkyd paints. The first surfactant free alkyd emulsion was consequently developed and its film properties characterized in paint formulation
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Rodriguez, Iara Hernandez. "Estudo experimental e modelagem do escoamento de emulsão inversa em tubulações." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18147/tde-11022015-102532/.
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O escoamento líquido-líquido, em especial o escoamento óleo-água, vem atraindo a atenção de pesquisadores devido à alta demanda pelo combustível fóssil no atual cenário petrolífero mundial e nacional. Os desafios tecnológicos colocados pelas descobertas de reservas de óleos pesados e altamente viscosos consideram, em especial, a preocupação por minimizar as perdas energéticas nas linhas. Emulsões inversas ou dispersões óleo-em-água, na qual o óleo se encontra disperso de maneira uniforme em água, caracteriza-se pela baixa viscosidade aparente, tornando-se um tipo de emulsão desejável em algumas etapas do transporte de petróleo. Esses fatos tornam essencial o estudo deste tipo de padrão para o dimensionamento e operação ótima de dutos de produção de petróleo. Contudo, não existe ainda um número abrangente de trabalhos sobre padrão disperso líquido-líquido, ao comparar com escoamento em fases separadas. Trabalhos sobre dispersões têm reportado redução de atrito sem a adição de substâncias químicas em regime turbulento. No entanto, não há ainda um entendimento satisfatório do fenômeno. Na maioria dos trabalhos, sendo quase todos realizados com óleos leves e pouco viscosos, a redução é reportada em dispersões água-em-óleo, com escassos trabalhos reportando o fenômeno em dispersões óleo-em-água. A pesquisa realizada tratou do estudo experimental e teórico de dispersões óleo-em-água em tubulações. O escoamento foi caracterizado a partir da obtenção de dados de holdup, gradiente de pressão por fricção, distribuição das fases e padrão de escoamento. Uma teoria foi proposta para explicar a redução de atrito detectada neste trabalho, baseada na existência de um filme fino de água que escoa em contato com a parede do tubo, a baixos números de Reynolds, evitando o contato direto do núcleo turbulento (mistura bifásica) com a parede do tubo. O referido filme líquido foi detectado e quantificado utilizando-se técnica visual. Além disso, um modelo dinâmico baseado na teoria de lubrificação hidrodinâmica foi desenvolvido como tentativa de explicar a formação do filme líquido parietal no escoamento turbulento de dispersões óleo-água.<br>Liquid-liquid flow, especially oil-water flow, has attracted the attention of researchers due to the high demand for petroleum in the current global scenario. The discovery of reserves of heavy and highly viscous oils creates new challenges which are mainly concerned with reducing the significant pressure drop in pipes. Inverse emulsion or oil-in-water dispersions in which the oil is dispersed in water is characterized by its low effective viscosity, making it a desirable type of emulsion in some steps of oil production. These facts make the study of dispersed liquid-liquid flow essential for the design and optimal operation of oil pipelines. However, the studies on such flow pattern are scanty in comparison to those on separate flows, as stratified and annular flow patterns. Drag reduction in oil-water turbulent flow without the addition of any chemical substance has been reported in some studies. This phenomenon has received increasing attention in recent years, because there is not a satisfactory understanding of its dynamics yet. Most studies, almost all using light oils, report drag reduction in dispersion of water-in-oil, with few studies reporting the phenomenon in oil-in-water dispersions. This research comprises an experimental and theoretical study on oil-in-water dispersions in pipes. Pressure gradient, holdup, phase distribution and flow patterns data were obtained to characterize the two-phase flow. A theory was proposed to explain the drag reduction detected in this work, based on the existence of a thin water film flowing in contact with the pipe wall at low Reynolds numbers, avoiding contact between the turbulent core (mixture) and the pipe wall. The liquid film was detected and quantified using visual technique. In addition, a dynamic model based on the hydrodynamic lubrication theory was developed as an attempt to explain the formation of the liquid film.
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Lira, Augusto César Santos de. "Avaliação de diferentes técnicas de dispersão para polimerização em miniemulsão." reponame:Repositório Institucional da UFSC, 2015. https://repositorio.ufsc.br/xmlui/handle/123456789/174123.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Química, Florianópolis, 2015.<br>Made available in DSpace on 2017-03-21T04:04:22Z (GMT). No. of bitstreams: 1
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Previous issue date: 2015<br>A formação de gotas submicrométricas demanda grandes quantidades de energia aplicadas ao sistema de modo a criar uma alta taxa de cisalhamento. Esta energia pode ser proveniente de agitação mecânica, ondas de ultrassom ou até mesmo o bombeamento de um fluido através de uma membrana. Neste trabalho é apresentado um estudo de diferentes técnicas para a produção de miniemulsões, como agitação mecânica utilizando um equipamento do tipo rotor-estator, dispersão com ultrassom e emulsificação por meio de um sistema composto de membranas cerâmicas e bomba. O sistema escolhido para este estudo foi uma miniemulsão de metacrilato de metila em água, frequentemente utilizada para reações de polimerização em miniemulsão. Objetivou-se dessa forma avaliar e comparar a técnica de emulsificação por meio de membranas frente às outras técnicas mais comumente utilizadas. Foram avaliadas duas configurações para o sistema de membranas, utilizando duas bombas diferentes (bomba de diafragma ou de engrenagem), além de serem estudadas condições operacionais diferentes, como velocidade tangencial e pressão. Obtiveram-se miniemulsões com diâmetros médios de gota de 285 a 550 nm, estáveis por um período de até 7 dias. De modo comparativo, utilizando as outras técnicas de dispersão, obtiveram-se diâmetros médios de gota de 95 a 170 nm, também estáveis por 7 dias. Ao serem realizadas as reações de polimerização, as miniemulsões preparadas com rotor-estator e dispersor ultrassônico permaneceram estáveis durante toda a reação, não ocorrendo grande distinção entre os valores dos diâmetros médios de gotas e de partículas resultantes. Para o sistema de membranas avaliado, após a polimerização, as partículas poliméricas produzidas apresentaram diâmetros bem inferiores aos diâmetros das gotas das miniemulsões monoméricas, evidenciando a ocorrência de outros mecanismos de nucleação, além da nucleação das gotas. Entretanto, os tamanhos das partículas poliméricas foram similares aos obtidos nos ensaios empregando outras técnicas de dispersão, em torno de 100 nm, com distribuições estreitas (PDI abaixo de 0,1), mostrando que o sistema de membranas proposto foi eficiente para o processo avaliado.<br><br>Abstract : The formation of submicron droplets demand large amounts of energy applied to the system to create a high shear rate. This energy can be derived from mechanical agitation, ultrasonic waves, or even the pumping of fluid through a membrane. This work presents a study of different techniques for producing miniemulsions such as mechanical stirring using a rotor-stator type device, ultrasonic dispersion and emulsification using a system consisting of a pump and ceramic membranes. The system chosen for the development of this study was a methyl methacrylate miniemulsion in water, often used for miniemulsion polymerization reactions. The objective was to evaluate and compare the different emulsification techniques. Two configurations for the membrane system were evaluated using two different pumps (diaphragm and gear pump), besides of that different system's operating conditions were studied, such as tangential velocity and pressure. Miniemulsions were obtained with mean droplet diameters around 285 to 550 nm stable by a period of 7 days. In comparison, miniemulsions were prepared using other dispersion techniques yielding average droplet diameters around 95 to 170 nm also stable for a period of 7 days. When the polymerization reactions were carried out, the miniemulsions prepared with rotor-stator and ultrasonic disperser remained stable throughout the reaction. Significant distinction between the values of the average diameters of droplets and resulting particles was not observed. For the membrane system assessed after miniemulsion polymerization, the produced polymer particles presented lower diameters than the diameters of the monomeric miniemulsions' droplets, indicating the occurrence of other nucleation mechanisms in addition to droplets nucleation. However, the polymer particles sizes were similar to those obtained in the assays employing other dispersion techniques, around 100 nm, with narrow distributions (PDI below 0.1), showing that the proposed membrane system was efficient for the evaluated process.
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Kolenová, Milada. "Příprava stabilních přírodních BB krémů a zkoumání jejich vlastností." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-414164.
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The aim of this diploma thesis was create a natural BB cream that, in addition to sufficient hydration, would protect the skin from sunlight, unify its colour tone and at the same time sufficiently cover any imperfections. After proposition a suitable recipe, it was necessary to determine the stability of the prepared BB creams. The stability was evaluated by comparing the results from the dispersion analyser LUMiSizer at various temperatures and current load tests in an oven. The pseudoplastic properties were confirmed by the rheology characterization of the flow properties, which makes the BB cream a continuous layer on the skin after it is spread. In order to protect against sunlight, it was necessary to determine the SPF and measure the colour shades of the prepared BB creams for comparison with commercially available preparations.
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FIDEL-DUFOUR, Annie. "Influence d'additifs anti-agglomérants sur l'agrégation et les propriétés de transport des hydrates de méthane cristallisant dans des émulsions eau/dodécane." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2004. http://tel.archives-ouvertes.fr/tel-00010236.
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Les hydrates de gaz sont des composés solides de type clathrate pouvant se former à partir de molécules de gaz hydrocarbonées sous pression et d'eau froide. Ces conditions sont réunies dans certaines conduites pétrolières et peuvent poser un problème de production. En effet, l'effluent pétrolier qui sort d'un puits de production contient toujours de l'eau et des molécules hydrocarbonées légères (méthane, éthane, propane) susceptibles de former un hydrate de gaz. Les hydrates de méthane ne sont pas naturellement présents dans les gisements de production car la température est beaucoup trop élevée (jusqu'à 200 °C). Par contre, le fluide pétrolier se refroidit lors de son transport dans une conduite, soit parce que la conduite est localisée dans une zone particulièrement froide, soit parce que la conduite est sous-marine, au contact avec de l'eau froide. Il peut alors se former des hydrates risquant d'obstruer les conduites. Pour prévenir leur cristallisation, la tendance actuelle est de coupler trois types d'approches: isolation des conduites, injection d'additif lors des phases critiques, réchauffement de la conduite par circulation d'eau chaude lors des bouchages accidentels. <br />Cette thèse participe à la modélisation des écoulements après formation d'hydrates. Il ne s'agit donc pas d'empêcher la cristallisation mais de s'intéresser à la rhéologie de l'écoulement après formation de cristaux. L'objectif à long terme est d'identifier l'origine de la transportabilité des coulis d'hydrates sous l'influence d'additifs dits « anti-agglomérants ».<br />Les mécanismes de cristallisation sont en effet très souvent couplés : germination, croissance, agglomération, attrition... La compréhension du mécanisme d'action d'un additif est donc une tache complexe, d'autant plus que la cristallisation est intimement liée au système physique dans lequel elle se développe. Les études cherchant à identifier les mécanismes de cristallisation, pour ensuite comprendre les effets d'additifs ont toutes (ou pratiquement) été effectuées dans des réacteurs fermés et systèmes simples (eau/gaz) (Herri (1996), Pic (2000)...). A l'inverse, des tests de validation d'additifs ont été effectués sur des boucles pilotes représentant un écoulement réel, donc complexe.<br />Notre travail se situe donc à mi-chemin des deux approches précédentes. Il s'agit de se rapprocher des conditions géométriques d'un écoulement pétrolier (boucle pilote) tout en conservant un système simple (eau/dodécane) avec pour objectif sur le long terme d'identifier le couplage : géométrie/cristallisation/influence des additifs.<br />Le dispositif expérimental (hauteur 12 m, largeur 3 m, longueur 6 m) réalisé dans le cadre de cette thèse est une boucle pilote de circulation reproduisant certaines conditions de l'écoulement d'un fluide pétrolier (émulsion eau dans huile) dans une conduite sous-marine, c'est-à-dire sous forte pression [1-10 MPa] et faible température [0-10 °C]. Les différentes parties de cet instrument sont :<br />· Le serpentin s'enroulant sur 3 niveaux,<br />· Le tube montant, plus souvent désigné dans sa terminologie anglosaxone par « riser ». A la base de ce tube est injecté du méthane de façon à alléger la colonne de fluide pour créer un effet ascenseur (terminologie anglosaxone « gaslift »). <br />· Le séparateur situé au sommet du riser sépare par gravité la partie gaz, de la partie liquide (eau, huile) qui redescend dans un tube parallèle au riser vers la boucle de circulation.<br />· Le système de recompression des gaz récupère les gaz du séparateur pour les réinjecter au bas du riser après augmentation de la pression.<br />Ce système expérimental est composé in fine de deux boucles circulant sur elles-mêmes : une boucle liquide et une boucle gaz. Ces deux boucles partagent une section commune composée du riser et du séparateur.<br />Ce dispositif a permis de réaliser des études rhéologiques sur la phase continue seule (dodécane) en fonction de la pression de méthane et sur des émulsions contenant diverses teneurs en eau et en additifs. Des études concernant la cristallisation des hydrates de méthane au sein des émulsions ont été réalisées en considérant l'influence de la teneur en eau puis celle de la teneur en additif sur la viscosité apparente des dispersions ainsi formées. Nous proposons enfin une modélisation reliant la cristallisation au comportement rhéologique.
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Nikola, Maravić. "Stabilizujući efekat polisaharidnih jedinjenja industrije šećera u proizvodnji emulzija." Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2019. https://www.cris.uns.ac.rs/record.jsf?recordId=111014&source=NDLTD&language=en.
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Stabilizatori na bazi biopolimera postaju posebno povoljna prirodna rešenja za primenu u kompleksnim sistemima, kao što su emulzije tipa ulja u vodi. U ovoj disertaciji je ispitan individualni i kombinovani uticaj tri stabilizatora na bazi polisaharida (vlakna šećerne repe, pektin šećerne repe i OSA maltodekstrin) na formiranje i stabilnost emulzija kukuruznog ulja u vodi. Ispitan je uticaj četiri različite tehnike emulgovanja (ultrazvučna homogenizacija, visokopritisna homogenizacija, membransko emulgovanje i rotor-stator homogenizacija). Sveobuhvatna karakterizacija koja je obuhvatala ispitivanje fizičko-hemijskih, strukturnih, tenziometrijskih, konduktometrijskih, viskozimetrijskih osobina ispitivanih polisaharida je prikazana u ovoj disertaciji. Dobijeni rezultati veličine kapi emulzija i njihove fizičke stabilnosti ukazuju na dobra stabilizaciona svojstva ispitivanih polisaharida. Interakcije između primenjenih stabilizatora na bazi polisaharida rezultovale su značajnim promenama veličine kapi, zeta potencijala, kriming indeksa i strukture emulzije.<br>Biopolymer based stabilizers become particularly favorable natural solutions for use in complex systems, such as oil-in-water emulsions. In following dissertation, the individual and combined effects of three polysaccharide based stabilizers (sugar beet fibers, sugar beet pectin and OSA maltodextrin) on the formation and stability of corn oil emulsions in water were tested. The influence of four different emulsion techniques (ultrasonic homogenization, high-pressure homogenization, membrane emulsification and rotor-stator homogenization) were examined. A comprehensive characterization that included the examination of physico-chemical, structural, tensiometric, conductometric, viscometric characteristics of the polysaccharides examined is presented in this dissertation. The obtained results of the emulsion droplet size and their physical stability indicate good stabilization properties of the polysaccharides examined. The interactions between the applied polysaccharide-based stabilizers resulted in significant changes in the droplet size, zeta potential, creaming index and the structure of the emulsion.
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Ljubica, Dokić-Baucal. "Uticaj molekularnih svojstava maltodekstrina na tehnološko ponašanje niskoenergetskih prehrambenih emulzija." Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2002. https://www.cris.uns.ac.rs/record.jsf?recordId=71467&source=NDLTD&language=en.
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Apstrakt je obrađen tehnologijama za optičko prepoznavanje teksta (OCR).Maltodekstini, hidrolizati skroba niskog stepena konverzije (dekstrozni ekvivalent manji od 20), imaju široku upotrebu u prehrambenoj, kozmetičkoj i farmaceutskoj industriji. U prehrambenoj industriji koriste se u niskoenergetskim prehrambenim emulzijama (majonez, salatni prelivi, namazi) kao zamena za masne materije da bi obezbedili viskozitet, poželjne senzorne osobine i smanjenje energetske vrednosti proizvoda.Viskozitet razblaženih rastora maltodekstrina različitog dekstroznog ekvivalenta i botaničkog porekla meren je kapilarnim viskozimetrom i izračunate su vrednosti unutrašnjeg viskoziteta za pojedine maltodekstrine. Vrednosti untrašnjeg viskoziteta i molekulske mase pokoravaju se zavisnosti Štaudingerove jednačine, iako su molekuli maltodekstrina relativno kratki i ne spadaju u grupu polimera. Utvrđena je mogućnost odredivanja DE- vrednosti viskozimetrijskin putem i izvedene su jednačine za dva opsega DE (5-10 / 10-20).Da bi se ispitalo ponašanje emulzija sa maltodekstrinima (emulgovanje) u procesnim uslovima, kao i osobine fmalnih proizvoda (tečljivost, mazivost) ispitivana je dinamika emulgovanja, veličina kapljica i reološko ponašanje, tj. uticaj različitih faktora na disperzione karakteristike emulzija suncokretovog ulja u vodi stabilizovanih prehrambenim emulgatorom, sa dodatkom maltodekstrina u kontinualnoj fazi.Utvrđeno je da osobine maltodekstina kao što je stepen konverzije (DE-vrednost) tj. veličina molekula maltodekstrina, utiču na dispezione i reološke osobine emulzija. Uticaj koncentracije ulja i maltodekstrina, kao i delimična zamena ulja maltodekstrinom, na osobine emulzija su takode ispitivane. Sa povećanjem koncentracije ulja, pri istoj koncentraciji maltodekstrina u kontinualnoj fazi, emulzije menjaju tip proticanja od pseudoplastičnog preko tiksotropnog do antitiksotrpnog. Atitiksotropija izazvana smicanjem rezultat je formiranja unutrašnje strukture emulzije usled povezivanja kapljica ulja preko molekula maltodekstrina kao i orijentacije i deformacije kapljica ulja i maltodekstrina.Dodatkom maltodekstrina za pri istoj koncentraciju ulja i vremenu emulgovanja dobijene su se emulzije sitnijih kapi.Emulzije sa niskom koncentracijom ulja (30%) sa maltodekstrinom u kontinualnoj fazi bile su nestabilne i pokazivale efekat isplivavanja na površinu (creaming), što je posledica interakcija molekula maltodekstrina i molekula emulgatora Tween 80 u kontinualnoj fazi i na površini kapi.<br>Abstract was processed by technology for Optical character recognition (OCR).Maltodextrins, low converted products of starch hydrolysis (dextrose equivalent less than 20), have been subject of various investigations due to their wide application in food industry, cosmetics and pharmaceuticals. They are used in various low energy food emulsions (mayonnaise, salad dressing, spreads) as fat replacer to provide desirable viscosity, texture and sensory fat-like mouthfeel.Viscosity of diluted maltodextrin solutions of different dextrose equivalent and botanical origin were determined by capillary visometer and intrinsic viscosity [q] of each tested maltodextrin was calculated. The values of [q] together with molecular mass M have shown applicability of Staudinger equation, regardless maltodextrin molecules are rather short. The possibility for the determination of DE-values of maltodextrins by viscometric method has been deduced and the equation was calculated for two ranges of DE (5-10/ 10-20).In order to assess behavior of sunflower oil in water emulsions stabilized with food grade emulsifier with addition of maltodextrins in continuous phase in processing (emulsification), as well as end products in application (pouring, spreading) the emulsification dynamics, globule size changes and rheological behavior, as well as, the influence of different factors on dispersion characteristics of such emulsions were studied.Dispersion and viscous properties of emulsions were influenced by certain specific maltodextrin characteristics such as degree of conversion (DE value) i.e. size of maltodextrin molecules. Influence of oil and maltodextrin concentration and partial substitution of oil with equivalent quantity of maltodextrin were investigated too. With increase of oil concentration at the same concentration of maltodextrin in continuous phase, emulsions undergo changes in flow type from shear-thinning to thixotropic and antithixotropic. Antithxotropy induced by shear, was result of formation of network due to two competing factors; linking of oil droplets through maltodextrin molecules as well as orientation of deformed oil droplets and maltodextrin molecules.Addition of maltodextrin, at the same oil concentration and emulsification time, resulted in formation of emulsions with smaller oil droplets.Emulsions with low oil concentration (30%) with maltodextrin in continuous phase were unstable, showing so called creaming effect. This was mainly due to interactions between maltodextrin and emulsifier Tween 80 molecules which took place in continuous phase and on droplet surfaces.
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Arcanjo, Samuel Arruda. "Preparação de emulsões complexas a partir de dispositivos de microfluídica." Universidade Federal de Viçosa, 2009. http://locus.ufv.br/handle/123456789/4238.
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Previous issue date: 2009-07-29<br>Emulsions are colloidal systems where one liquid is dispersed in another liquid where the two liquids are immiscible. The control of these dispersions can bring important contributions to science and society since this kind of colloidal system has many and important applications in the food and pharmaceutic area and also in the material science. This work has the main purpose to develop and improve monodisperse emulsions production techniques using simple and low-cost devices. It is shown the production of simple emulsions using devices built from glass capillary tubes. Besides, the drops diameter dependence with the phases flow rate is verified. Solid particles were made from droplets of poly(styrene) dispersed in chloroform, followed by the evaporation of the chloroform, using these devices. Although the glass capillary tube devices show good results, we have made emulsions, for instance, of (80±1) μm with standard deviation of 1,3 μm (σ/dm = 1, 6%), they have limitations concerning the configuration of the tubes. Another kind of device built was made basically from microchannels produced in glass microscope slides using hydrofluoric acid to attack the slide surfaces. The slides were sealed using epoxy glue and the final result were channels with controlled values of depth and width. The dependence of the drops diameter with the continuous and disperse phases flow rate were made to test the devices quality. High quality emulsions were obtained with tipical values for diameter and standar deviation about 100 μm and 2%. Four different channel configurations were tested and the configuration where the channels were built as a cross (one channel carrying the disperse phase and two channels carrying the continuous phase) shown better results then the devices with only two channels (one channel carrying each phase).<br>Emulsões são sistemas coloidais onde um líquido é disperso em outro líquido imiscível. O controle dessa dispersão pode trazer importantes contribuições para a ciência e para a sociedade, já que este tipo de sistema coloidal apresenta variadas e importantes aplicações nas áreas alimentícia, farmacêutica e de materiais. Este trabalho tem como objetivo principal desenvolver e aperfeiçoar técnicas de produção de emulsões com baixa dispersão de tamanhos utilizando dispositivos simples e de baixo custo. Apresenta-se, assim, a técnica de produção de emulsões simples através da utilização de dispositivos construídos a partir de tubos capilares de vidro. Além disso, verifica-se a dependência do diâmetro das gotas das emulsões produzidas com a vazão da fase contínua e dispersa. Utilizando este dispositivo, produzem-se também partículas sólidas a partir da preparação de gotas de poliestireno dissolvido em clorofórmio e posterior evaporação do clorofórmio. Embora esse tipo de dispositivo apresente bons resultados, sendo possível produzir emulsões, por exemplo, com diâmetro médio das gotas igual a (80±1) μm e desvio padrão de 1,3 μm (σ/dm = 1, 6%), ele tem limitações quanto ao número de configurações dos fluxos possíveis de se trabalhar. Outro dispositivo produzido constitui-se basicamente de microcanais produzidos em lâminas de microscópio por ataque controlado de ácido fluorídrico. A vedação superior dos canais é feita utilizando cola epóxi (araldite) tendo-se, assim, canais de largura e profundidades controladas. Para testar a qualidade deste tipo de dispositivo, fez-se também a verificação do diâmetro das gotas de emulsão produzidas com a vazão da fase contínua ou dispersa, tendo sido possível a produção de emulsão com baixa dispersão de tamanhos, produzindo para dada condição, emulsões com diâmetro médio das gotas da ordem de (100±1) μm com desvio padrão típicos de 2%. Foram testadas quatro diferentes configurações de canais, onde as configurações em cruz (um canal contendo a fase dispersa e dois canais com a fase contínua) mostraram melhores resultados que configurações com apenas dois canais (um por fase).
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Fanzar, Abdelaziz. "Développement d’un code numérique pour la simulation et l’étude de l’hydrodynamique et de la physico-chimie de milieux diphasiques incompressibles. Cas d’une goutte d’eau dans l’huile de paraffine." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4339.
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Depuis plusieurs décennies, une importante activité scientifique se concentre sur la description numérique, théorique ou expérimentale de l'hydrodynamique des écoulements multiphasiques. Ces écoulements sont caractérisés par l'existence d'interfaces, et d'une force à l'interface, la tension superficielle, séparant généralement deux fluides non miscibles. Un cas d'étude dans ce contexte est le problème du drainage d'une unique goutte dans une phase continue, l'ensemble étant soumis à la gravité. Ce système fait apparaître des écoulements récemment décrits pour une goutte d'eau dans l'huile de paraffine. Ce système constitue également un modèle simple pour l'étude des propriétés aux interfaces, Mais d'un point de vue numérique, se pose alors le problème de la stabilité des algorithmes pouvant être utilisés. Les effets aux interfaces impliquent en effet des domaines spatiaux très limités dans lesquels les grandeurs physiques entre les deux fluides sont discontinues. D'importants artéfacts numériques peuvent alors être générés dans les simulations et faire perdre la richesse de la physico-chimie du système considéré. Le problème de la simulation d'écoulements multiphasiques intéresse aussi bien le monde académique que le monde industriel. L'objectif de ce travail de thèse est donc d'implémenter les techniques numériques les plus récentes et de développer un code pour permettre la simulation de l'hydrodynamique de systèmes dispersés. Pour parvenir à ce but, il reste encore des problèmes algorithmiques importants à résoudre comme la prise en compte des effets thermocapillaires et thermosolutaux. Ces deux derniers points sont l'objet de cette thèse<br>For several decades, an important scientific activity has focused on the numerical, theoretical and experimental hydrodynamics of drops. This work presents numerical results of a single droplet in the gravity field and in non-isothermal conditions. The simulation such a multiphase system is important in both academic and industrial world. This is particularly the case in the field of emulsions, wetting problems and evaporation. To achieve this goal, there are still important algorithmic problems due to the free moving interfaces and the description of capillary effects. Here, a Volume of Fluid technique has been implemented with high order temporal and spatial schemes to preserve the sharpness of the drop interface. The system under consideration is a simplified model consisting in a single water droplet in a continuous paraffin oil phase. These liquids are immiscible and non-compressible and the overall evolution is unsteady. Capillary contributions such as temperature and surfactant dependent surface tension are fully accounted for. This presentation is aimed to show the capabilities of VOF techniques for the simulations of unsteady multiphase systems in non-isothermal configurations. The role of the droplet initial position and temperature field is described with good numerical stability. There are still important problems remaining in the simulation of free interface systems with such a technique. Spurious currents induced by the description of capillarity can in particular come into play. But these latter can be controlled once the droplet average velocity due to drainage becomes large enough
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Fanzar, Abdelaziz. "Développement d’un code numérique pour la simulation et l’étude de l’hydrodynamique et de la physico-chimie de milieux diphasiques incompressibles. Cas d’une goutte d’eau dans l’huile de paraffine." Electronic Thesis or Diss., Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4339.
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Depuis plusieurs décennies, une importante activité scientifique se concentre sur la description numérique, théorique ou expérimentale de l'hydrodynamique des écoulements multiphasiques. Ces écoulements sont caractérisés par l'existence d'interfaces, et d'une force à l'interface, la tension superficielle, séparant généralement deux fluides non miscibles. Un cas d'étude dans ce contexte est le problème du drainage d'une unique goutte dans une phase continue, l'ensemble étant soumis à la gravité. Ce système fait apparaître des écoulements récemment décrits pour une goutte d'eau dans l'huile de paraffine. Ce système constitue également un modèle simple pour l'étude des propriétés aux interfaces, Mais d'un point de vue numérique, se pose alors le problème de la stabilité des algorithmes pouvant être utilisés. Les effets aux interfaces impliquent en effet des domaines spatiaux très limités dans lesquels les grandeurs physiques entre les deux fluides sont discontinues. D'importants artéfacts numériques peuvent alors être générés dans les simulations et faire perdre la richesse de la physico-chimie du système considéré. Le problème de la simulation d'écoulements multiphasiques intéresse aussi bien le monde académique que le monde industriel. L'objectif de ce travail de thèse est donc d'implémenter les techniques numériques les plus récentes et de développer un code pour permettre la simulation de l'hydrodynamique de systèmes dispersés. Pour parvenir à ce but, il reste encore des problèmes algorithmiques importants à résoudre comme la prise en compte des effets thermocapillaires et thermosolutaux. Ces deux derniers points sont l'objet de cette thèse<br>For several decades, an important scientific activity has focused on the numerical, theoretical and experimental hydrodynamics of drops. This work presents numerical results of a single droplet in the gravity field and in non-isothermal conditions. The simulation such a multiphase system is important in both academic and industrial world. This is particularly the case in the field of emulsions, wetting problems and evaporation. To achieve this goal, there are still important algorithmic problems due to the free moving interfaces and the description of capillary effects. Here, a Volume of Fluid technique has been implemented with high order temporal and spatial schemes to preserve the sharpness of the drop interface. The system under consideration is a simplified model consisting in a single water droplet in a continuous paraffin oil phase. These liquids are immiscible and non-compressible and the overall evolution is unsteady. Capillary contributions such as temperature and surfactant dependent surface tension are fully accounted for. This presentation is aimed to show the capabilities of VOF techniques for the simulations of unsteady multiphase systems in non-isothermal configurations. The role of the droplet initial position and temperature field is described with good numerical stability. There are still important problems remaining in the simulation of free interface systems with such a technique. Spurious currents induced by the description of capillarity can in particular come into play. But these latter can be controlled once the droplet average velocity due to drainage becomes large enough
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(7027283), Joshua D. Mathews. "Biphasic Dispersion Fuels for High Performance Hybrid Propulsion." Thesis, 2019.
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This thesis describes a novel approach to augmenting the combustion performance of hybrid rocket fuels, specifically in terms of regression rate and combustion efficiency. Liquid additives are emulsified into molten paraffin wax using nonionic surfactants and cured to form cylindrical fuel grains. Fuel grains were tested in a lab scale, optically accessible hybrid rocket motor and compared to the performance of neat paraffin fuel grains.
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Cheng, Chih-Ping, and 鄭志平. "A study on the dispersion properties of emulsion formulations affecting the antigen delivery and vaccine immunogenicity." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/40171153317568065098.
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碩士<br>國立清華大學<br>生物科技研究所<br>101<br>Many new vaccine candidates comprising purified recombinant proteins or synthetic peptides offer substantial advantages over inactivated microorganism vaccines in terms of safety and ease of manufacturing. But protein/peptide-based vaccines in most cases have low immunogenicity and need adjuvant to elicit protective and long-lasting immune responses. Water-in-oil emulsions have been evaluated and achieved long-term protective immune responses. However, this type of emulsions are crowded in the oily phase and causing local reactions at the site of injection. On contrary, it is well documented that the oil-in-water emulsions like MF59 can quickly induce and create immunocompetent environment at the site of injection. In this study, we prepared different emulsion formulations using non-ionic surfactants (PEG-b-PLACL, Tween®80 and Span®85) with various hydrophilic-lipophilic balance values of the surfactant systems under the optimized manufacturing procedure. Furthermore, we attempted to examine the effects of the surfactant components and manufacturing process of the prepared emulsion formulations on the physicochemical characteristics (including stability, electrolytic conductivity, microscopic aspects, size distribution, in vitro release and in vivo distribution) and adjuvant activity (including B-cell immunoassays and T-cell immunoassays). After the optimization of emulsification procedure, the homogeneous nanoparticles were obtained in the emulsions and we also found that the physicochemical properties and the immunogenicity of formulated vaccines are strongly influenced by the compositions and manufacture process. These results were obtained in this study with potential features provide experiment evidences and suggest strategies for the design of effective antigen delivery and vaccine development.
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Vicic, Michael. "Rheology and microstructure of complex fluids: dispersions, emulsions and polymer solutions." Thesis, 1999. https://thesis.library.caltech.edu/1287/1/Vicic_m_1999.pdf.
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The rheology and microstructure of complex fluids are intimately related, and this relationship is explored to gain a deeper understanding of the physics of colloidal dispersions, emulsions and polymer solutions.
The nonequilibrium microstructure and rheological properties of dispersions in steady, simple shear flow are calculated by solving the Smoluchowski equation as a function of dimensionless shear rate. The particles have a purely repulsive interaction with an hydrodynamic radius, a, and a thermodynamic radius, b. For hard spheres, b/a --> l, shear thinning is caused by a decrease in the Brownian contribution since Brownian motion becomes less important with increasing shear. Shear thickening occurs because of an increase in the hydrodynamic viscosity caused by the increased probability of finding particles near contact with increasing shear when particles hydrodynamically interact. The first normal stress difference changes sign since Brownian and hydrodynamic contributions have opposite signs, while the second normal stress difference is always negative. Scaling arguments are made to extend these dilute results for concentrated dispersions. Similar calculations and analyses are performed to study the effects of hydrodynamic interactions and varying b/a ratios on rheology and microstructure.
Scaling arguments for the volume-fraction dependence of the bulk stress of emulsions at the critical capillary number are presented along with experimental evidence using an unstabilized emulsion of polymerized castor oil dispersed in polydimethylsiloxane. It is shown that the droplet contribution to both the relative shear viscosity and first normal stress difference is linear in volume fraction for a given viscosity ratio for dilute to moderately-concentrated emulsions in steady, simple shear flow.
Stress jump measurements are performed for the first tune for (i) shear startup and (ii) polymer solutions in shear. The startup viscosity of a polymer solution of polyacrylamide in fructose-water at equilibrium is equal to the measured high frequency dynamic viscosity, as expected, since both methods measure the viscous contribution to the viscosity associated with the equilibrium microstructure. Since polymer solutions exhibit stress jumps different from the solvent viscosity, effects of shear on the hydrodynamic viscosity can be investigated.
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Chen, Chia-Nan, and 陳嘉南. "Separation of Amino Acids Using Non-dispersive Supported and Emulsion Liquid Membranes." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/70137479781688454540.
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碩士<br>元智大學<br>化學工程學系<br>93<br>The recovery and separation of amino acids from aqueous solutions by using a hollow fiber membrane module have been studied in this paper. Due to the zwitterionic character of amino acids, they had specific isoelectric points (pI). Amino acids could exist as the cationic or anionic form by adjusting the pH value less and greater than their isoelectric points in aqueous solutions. Therefore, a cation-exchange carrier, D2EHPA, may be applied to extract anionic forms of amino acids and to separate two amino acids.
About the selectivity of binary amino acids, it was found that the larger the pH value, the larger the selectivity (1 < pH < 7). It was also found that the larger the concentration of D2EHPA in the organic phase, the larger the recovery.
The hollow fiber experiments were performed by changing the pH value, the D2EHPA concentration, the acidity of strip phase, the concentration ratio of L-phenylalanine and L-aspartic acid in the feed phase, and the flow rate of all phase. It was shown that an increase of D2EHPA concentration in the organic phase and the concentration of the acid in the strip phase would enhance the selectivity. The increase of pH value in the feed phase and the ratio of [Asp]aq/[Phe]aq in the feed phase would enhance separation factor. The selectivity was in the range 1.3 ~ 18.5 .
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Smith, Peter Griffin. "Stabilization of dispersions in carbon dioxide and in other low-permittivity media." Thesis, 2006. http://hdl.handle.net/2152/2960.
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Šrejma, Robert. "Granulometrie nanočástic z kopolymerů alifatických hydroxykyselin." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-343165.
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The diploma thesis is focused on the study of influence on the composition of the system to the size of the nanoparticles from aliphatic polyesters with linear and branched molecules constitution. The emulsion method for distributing of solvent was chosen for preparation of nanoparticles. The theoretical part describes the nanoparticles, its origin and application. The following part is applying to biodegradable polymers, especially PLGA. There is also a mention of antifungal agent terbinafine. The nanoparticles are prepared of this substance. The process is described in the experimental part of thesis. The experimental part is testing different composition of samples. A main emphasis is on the choice of polymer solvent and emulsifier. There are also applied mixtures of solvents and emulsifiers. The important aspect is the evaluation of incorporated terbinafine, which has been the model drug. Prepared dispersions were exposed to stress conditions in the form of several days-storage and centrifugation.
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Športeň, Radek. "Vliv formulačních faktorů na velikost polyesterových nanočástic." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-344009.
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In the theoretical part of this thesis are described various types of nanoparticles, such as polymeric particles, liposomes, micelles and solid lipid nanoparticles. There are presented basic informations concerning methods of particles preparation in the laboratory conditions such as solutions of polymers dispersion methods by intensively stirring, coacervation of the solutions of polymers, polymeration methods in dispersions, and the exploitation of methods of dispersion of polymeric solutions in the supercritical solvents. In the folowing part of this thesis are some concise informations about the methods of evaluation of basic parameters of the nanoparticulate systems. There are summarised the trivial informations concerning granulometry of particles, their zeta potential, encapsulation effectivity of drugs, and also about the particles shape factor. The focus of this thesis is in the experiment, the main deal were in minimisation of the particle size prepared by the method of emulsification of biodegradable aliphatic α-hydroxyacids polyesters solutions. The main process arrangement was the selection of the appropriate solvent of polymers in the inner emulsion phase and the founding for the mostly efficient emulsifier during the dispersion process of polymer solutions. In process of the...
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Svobodová, Dana. "Částice s protimikrobním stříbrem." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-344076.
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Charles Univerzity in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Candidate: Dana Svobodová Supervisor: doc. RNDr. Milan Dittrich, CSc. Diploma thesis title: Particles with antimicrobial silver The theoretical part of this diploma thesis outlines a brief overview of recent findings on silver nanoparticles. Further, it concerns the kinetic properties of colloidal systems, methods of evaluating the size and shape of colloidal particles, mechanism of antimicrobial activity of colloidal silver and methods of preparation of nanoparticles. Concise information about the toxicity of silver nanoparticles and their impact on the environment is also included. In the experimental part comprehensive report on the results of measurements of granulometric characteristics of microparticles and nanoparticles by photon correlation spectroscopy (PCS) is included. The influence of various modifications of preparation procedures and processing on stability, size and the polydispersity of the size in terms of the volume and intensity diameter of the particles with elemental silver deposited on the surface was studied. Optimisation of the disperse system, quality control of the content of colloidal particles by subsequent reduction, the possibilities of using centrifuge and...
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Jaworski, Jakub. "Granulometrická charakterizace nanočástic metodou PCS." Master's thesis, 2019. http://www.nusl.cz/ntk/nusl-397344.
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In the theoretical section of presented diploma thesis are discussed various nanoparticles such as micelles and liposomes, solid lipid nanoparticles and polymeric nanoparticles. Special attention was focused on copolymer PLGA. There are characterized different procedures in the preparation of nanoparticles. From the approches for nanoparticles evaluation are chosen measuring size of nanoparticles and their zeta potential. The experiment was almost unambiguously focused on study of effect of diffrent factors on nanopartlicles size and distribution from linear PLGA and PLGA used for branching of tripentaerythritol and polyacrylic acid. Keywords: nanoparticles, size, size distribution, zeta potential, interactions of nanoparticles
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Pacheco, de Moraes Raul. "PUSHING THE BOUNDARIES OF CONCENTRATED DISPERSIONS, High Solids Content Bimodal Latex for Paper Coating Applications." Thesis, 2011. http://hdl.handle.net/1974/7346.
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New processes for the production of polymeric dispersions with high solids content and low viscosity were developed, investigated and characterized. The specifications required for the desired application of paper coating, which constitutes one of the major innovative aspects of this thesis, requires in average particle sizes smaller than 200 nm. This particle size is significantly smaller than obtained in previous work in this area. The main objective of this project was to increase the solids content of existing products from ~50 to ~60 wt% while keeping the viscosity at low levels (< 1200 mPa•s at 20 s-1).
In order to produce high solids content latexes with low viscosity, bimodal particle size distributions were resorted to. To obtain highest packing fraction, the small particle size population should be about 7 times smaller than the large particles, bringing the size of the small particles to less than 30 nm.
Modified (micro)emulsion processes were developed in order to produce small particle size latex with reduced surfactant concentration and increased solids content. The large particle population was developed using a semi-batch emulsion polymerization process, simulating a product that is commercially available (~52 wt% solids content and viscosity of ~500 mPa•s at 20 s-1). To increase the solids content of this product up to 60 wt%, a second population of small particles was created using two approaches.
In the first approach, the small particles were generated in situ using the modified (micro)emulsion approaches developed previously. This process resulted in latexes of ~ 60% solids content and viscosities lower than 500 mPa•s at 20 s-1.
In the second approach, the second population of particles was created by the addition of seeds by using small cross-linked particles as pseudo inert-fillers. This process resulted in products with ~58% solids and viscosities lower than 1400 mPa•s at 20 s-1. The slightly decreased solids content and increased viscosity relative to the previous approaches is due to the difficulty in producing cross-linked seeds with particle sizes smaller than 30 nm at an acceptable concentration, causing deviations from ideal conditions.<br>Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2011-05-03 13:58:44.22
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Li, Yee, and 李翊. "Water with ultra-low concentration of surfactant as dispersed solvent-assisted emulsion dispersive liquid-liquid microextraction for the determination of organochlorine pesticides in aqueous samples." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/10622857345892410400.
Full textAbstract:
碩士<br>國立清華大學<br>化學系<br>100<br>The conscious of environmental protection is beginning to wake up. The harmful materials are also starting to be forbidden and diminished. Besides, the complicated matrix of environmental samples and trace amount of analyte make up placing importance on the preconcentration technique. In recent years, dispersed liquid-liquid microextraction (DLLME) has been developed particularly rapid, which experimental process is simple, fast, and low cost … and so on. But it used a lot of organic matter as dispersed solvent which can cause environmental burden and increase the extraction solvent with the analyte dissolved in the water. In this studty, we replace large amounts of organic to water containing very low concentration (1 mgL－1) of surfactant as the dispersed solvent which assisted a small amount of extraction solvent (10~12 μL) to emulsion. We used microinjection needle back and forth four times to mix within 10 seconds and then injected into water samples for extraction. We select low toxic non-chloro extraction solvent by using the improved solvent collection system (ISCI) which developed in our laboratory. And than use gas chromatography with electron capture detector (GC-ECD) to analye five common organochlorine pesticides like heptachlor, α-Endosulfan, p,p'-DDE, o,p'-DDD, Endrin in water sample. Developed a pre-treatment combined with enrichment extraction method which is sensitive, simple, fast and more environmentally friendly and used to compare with another methods.
In the first study, we used dodecyl acetate (12 μL) as the extraction solvent. Under optimized conditions, the results indicate that linear range of the method was 5~5000 ngL－1 with the R2 ≧0.9963, the method detection limit from 1 to 5 ngL－1, the quantitative detection limit from 3 to 17 ngL－1. The precision for inter-day was within 6.1~12.9 %. The precision for intra-day was within 9.7~14.4 %, the enrichment factor between 1901 and 3530. In lake water, the absolute recoveries were within 20.8~43.5 %, the relative recoveries were within 83.2~109.8 %, the precision from 7.1 % to 14.8 %. In sea water, the absolute recoveries were within 19.9~49.2 %, the relative recoveries were within 85.4~115.9%, the precision from 3.0 % to 13.6 %.
In the second study, we used 2-dodecanol (10 μL) as the extraction solvent. Under optimized conditions, the results indicate that linear range of the method was 1~10000 ngL－1 with the R2 ≧0.9970, the method detection limit from 0.5 to 2 ngL－1, the quantitative detection limit from 1.7 to 6.7 ngL－1. The precision for inter-day was within 4.0~5.1 %. The precision for intra-day was within 5.0~10.3 %, the enrichment factor between 1881 and 3108. In sea water, the absolute recoveries were within 25.7~42.2 %, the relative recoveries were within 96.3~111.2 %, the precision from 1.2 % to 8.5 %. In stream water, the absolute recoveries were within 22.4~41.9 %, the relative recoveries were within 90.7 ~107.9 %, the precision from 1.4 % to 6.4 %.
We developed a simple, rapid method of extraction. We used very small amount of volume, cheap, low toxicity, halogen-free extraction solvent and used water which was environmentally friendly, very low amount of volume, containing very low concentrations of surfactants as a dispersed solvent. It can be emulsified completely in a very short period of time. The method has very low detection limit and a high enrichment factor. The application of this experiment on the lake, sea and stream water with good recovery and precision. This method provided very convenient and high availability pre-treatment methods in environmental samples.