Dissertations / Theses on the topic 'Emulsion'
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Tsavalas, John George. "A molecular level investigation of hybrid miniemulsion polymerization." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/11153.
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Duffus, Laudina Jeneise. "Edible pickering emulsion technology : fabrication of edible particle stabilised double emulsions." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7456/.
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Water-in-oil-in-water (W/O/W) double emulsion systems provide an innovative approach for the development of low-fat healthier foods. By replacing a proportion of the oil phase of a simple oil-in-water (O/W) emulsion with an internal water phase, the overall oil volume within the emulsion system can be decreased, with potentially negligible changes to its organoleptic properties. However, double emulsions are notoriously unstable for adequate periods of time, largely due to the existence of two oppositely curved water-oil (W/O) and oil-water (O/W) interfaces in close proximity. The present study investigates the use of Pickering stabilisation in order to enhance the stability of double emulsions. Pickering stabilisation mechanisms are reputed for superior, longer term stabilisation capacities when compared to conventional surfactant stabilised emulsions, but edible particles with Pickering functionality are scarce. The work in this thesis explores the impact of introducing Pickering stabilisation to a double emulsion structure, initially at only one of the two water/oil interfaces (either W/O or O/W) and ultimately across the entire interfacial areas. Initial work conducted centred on investigating the role of a range of edible particulates as potential Pickering stabilisers in simple emulsions (both W/O and O/W emulsion types). Based on the knowledge gained from these studies, a range of Pickering-Surfactant stabilised double emulsions (with particles or surfactant stabilising alternate interfaces), using a range of surfactants, and Pickering only stabilised double emulsion systems were prepared and analysed in terms of their microstructure, stability and encapsulation efficiencies.
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Zhuang, Jianqin, and Ruediger Voelkel. "Emulsion droplet size distribution by PFG NMR: high concentrations, small radii, and suspo-emulsions." Diffusion fundamentals 3 (2005) 37, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A14327.
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Kalinin, Sergey. "Charm studies in emulsion." Université catholique de Louvain, 2006. http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-05302006-191314/.
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Neutrino-nucleon scattering is an effective way to investigate the inner structure of the nucleon, to extract the Standard Model parameters and to explore heavy quarks production dynamics. In the last decades, several experiments have been constructed to study weak interactions of neutrinos with nucleons. One of them was CERN-WA95 experiment operated by the CHORUS collaboration. It is based on a hybrid detector with nuclear emulsion as a target followed by electronic devices. Nuclear emulsion provides three dimensional spatial information with an outstanding resolution of the order of one micron. Therefore, it is ideal to detect short-lived particles. A special technique has been developed to reconstruct events in the emulsion which allows to perform a detailed investigation of events such as charmed hadrons production by neutrinos. As a result, the backround in the selected charm sample is up to six times lower compared to similar experiments. Such a method also permits to make direct measurements of some quantities instead of model fittings. This thesis is devoted to the study of the muonic decays of charmed hadrons and their production in emulsion. Manual inspection of charm events gives a complete reconstruction of charm decay topology. The extraction of the inclusive muonic branching ratio is based on the ratios per number of charged daughters in charm decay. Such an approach allows to separetely measure the muonic branching ratios for neutral and charged charm particles. Finally, normalization of the events with a muon in the final state to the charged current events gives dimuon production rate which is found compatible with the previous experiments. On top of that, preliminary results are shown for Bjorken x distribution and for a direct measurement of the Vcd Cabbibo-Kabayashi-Maskawa matrix element.
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Song, Zhiqiang. "Kinetics of emulsion polymerization." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/10148.
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Snell, David John. "Ultrasonically assisted emulsion polymerisation." Thesis, University of Bath, 2002. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760798.
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Josephides, Dimitris Noel. "Optimising monodisperse emulsion creation." Thesis, King's College London (University of London), 2015. http://kclpure.kcl.ac.uk/portal/en/theses/optimising-monodisperse-emulsion-creation(399fe892-a5e6-4dab-941a-457e620d651f).html.
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Monodisperse emulsions are a special class of emulsion where all droplets are of uniform size. The properties of emulsions (rheology, appearance, stability, reaction kinetics) are determined by the properties of both continuous and dispersed phases but also by the characteristics of the droplets themselves. It is for this reason that monodisperse emulsions are often sought after, as droplet size can have such a large influence upon emulsion behaviour. Having a uniform emulsion results in more predictability and allows for easier design in emulsion properties. Monodisperse emulsions find uses in many academic and industrial fields including pharmaceuticals, food science, paints, and coatings. This work covers two broad approaches to monodisperse emulsion creation; microfluidics and controlled shear. Microfluidics is a rapidly emerging technology where liquid flows are constrained to sub-millimetre channel sizes thus creating highly laminar and controllable flows. The methods are used in various lab on chip, and droplet creating applications. A study is undertaken on the nature of buoyancy-driven formation of drops from microchannels, attempting to further understand the fundamental principles of monodisperse drop generation at nozzles. Droplet producing microfluidic devices often suffer, however, from jetting when the desired emulsions are viscous or have low interfacial tensions, resulting in polydispersity. This work introduces two methods to overcome this, surfactant shielding and core-shell templating. Surfactant shielding is a method by which the nozzle of a droplet producing capillary tip is protected from surfactants by a tertiary, pure continuous phase thus limiting the reduction of interfacial tension at the point of droplet creation. Core-shell templating is a method of introducing water droplets into the stream of a would-be jetting system. These water droplets introduce regular instabilities which have the effect of forcing the system into a quasi-dripping regime and thus create highly monodisperse viscous emulsions. Controlled shear is another method for creating monodisperse emulsions whereby a coarse emulsion is subjected to a uniform shear stress resulting in a smaller more monodisperse emulsion. The work investigates two geometries for doing this, a cylinder-curved plate and a cylinder-flat plate. Both these designs are shown to have higher throughput rates than conventional shear methods. In the final part of this work, microfluidics and controlled shear are combined in an attempt to utilise the contrasting benefits found in both techniques. A study is undertaken in the possibility of shearing monodisperse precursor emulsions created via microfluidic techniques, to obtain uniform emulsions of much smaller size. A microfluidic shear cell is also introduced which aims to combine the benefits of a shear device (increased throughput rates, ability to handle viscous fluids) with the benefits of microfluidics (no moving parts, more control).
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Pu, Xiaolu. "Impact of hydrophilic emulsifier and emulsion microstructure on aroma release over w/o/w emulsions." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/52014/.
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In this thesis, the impact of the interactions between the hydrophilic emulsifiers and aroma compounds as well as emulsion microstructure including droplet size, droplet size distribution, emulsion stability and creaming on aroma release over water-in-oil-in-water (w/o/w) emulsions was investigated. Polyglycerol polyricinoleate (PGPR) was used as the only hydrophobic emulsifier to stabilise the internal water droplets in the primary water-in-oil (w/o) emulsion of the w/o/w emulsions throughout this research. Three hydrophilic emulsifiers investigated to stabilise the w/o droplets in w/o/w emulsions included a low molecular weight non-ionic surfactant, polyoxyethylene 20 sorbitan monolaurate (Tween 20), a chemically modified starch, octenyl succinic anhydride (OSA) starch and a protein, pea protein isolate (PPI), as the large molecular weight emulsifiers. The two emulsification methods of high shear mixing and stirred cell membrane emulsification were used. Controls of water and oil-in-water (o/w) emulsions were prepared with the formulation and process conditions as for the w/o/w emulsions. Emulsion microstructure was characterised in terms of droplet appearance, droplet size, droplet size distribution as well as emulsion stability over time. Both static and dynamic headspace analyses were carried out to investigate the aroma release behaviour over w/o/w emulsions. The results showed that w/o/w emulsions were a suitable vehicle for short time aroma entrapment, which was most successful for the hydrophilic aroma acetoin compared to the hydrophobic aromas acetyl pyridine and hexanal. This entrapment of the hydrophilic aroma resulted from the barrier of the oil phase in the w/o droplets to delay its diffusion or the PGPR micelles in the oil phase to entrap it in the polar inner core. The complex food emulsifiers OSA starch and PPI were for the first time successfully used in stirred cell membrane emulsification to produce similarly sized o/w and w/o/w emulsions. These were produced to eliminate the effect of droplet size in the study of aroma release. The release of aromas (i.e. diacetyl and 3-pentanone) was affected by the combination of the type of the hydrophilic emulsifier (Tween 20, OSA starch and PPI) and the type of the emulsion system (i.e. o/w and w/o/w emulsions) as well as the emulsion microstructure including droplet size, emulsion stability, interface thickness, creaming and diffusion of the internal water phase into the external water phase of w/o/w emulsions. The thinner interface laden by Tween 20 might lead to a quicker diffusion of the hydrophobic aroma 3-pentanone from the w/o droplets into w2. OSA starch interacted with the hydrophilic aroma diacetyl and 3-pentanone, and PPI interacted with 3-pentanone. These findings help to better understand the effect of the hydrophilic emulsifier and emulsion microstructure on aroma release and present a novel study to produce similarly sized emulsion droplets with complex food emulsifiers.
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Woodward, Rob. "Engineered emulsions, polymer structured oils and responsive polymer nanoparticles via polymer design and emulsion templating." Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/10493/.
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The synthesis of branched copolymers with precise composition, specifically the ratio of methacrylic acid (MAA) to ethylene glycol (EG) has been demonstrated. These polymers were used to stabilise dodecane oil-in-water emulsion droplets. It was demonstrated in the literature that branched copolymers containing a 1:1 ratio of MAA:EG formed pH-responsive emulsions, capable of triggered inter-droplet hydrogen bonding to form engineered emulsions (EE). The effect of varying this ratio on the rate of engineered emulsion formation, and the resulting strength and stiffness of the emulsion droplet aggregates was investigated. This control over systems is exemplified by the demonstration of selective acid-triggered assembly of binary mixtures of droplets stabilised by polymer containing only EG functionality with droplets stabilised by polymers containing only MAA functionality. EEs stabilised using a branched copolymer containing a 1:1 ratio of MAA:EG were produced and allowed to dehydrate, leading to the removal of water from droplet interstitial sites. The resulting single-phase materials are known as polymer-structured oils (PSOs), held structurally by the inter-droplet polymer-polymer interactions. These polymer boundaries provide enough of a barrier between droplets to prevent coalescence upon the removal of water, allowing reversible hydration of PSOs to reform EEs. The production of large volume, well-defined EEs produced via the hydrolysis of glucono-δ-lactone (GδL) to gluconic acid in an emulsion’s water phase was investigated. This process provides a homogeneous pH trigger for the formation of EEs, eliminating the slow diffusion of HCl. A homogeneous pH trigger also allows the formation of EEs to be studied in situ using rheology. A comparison between GδL and a conventional HCl trigger is presented. Branched copolymer-stabilised ethyl acetate o/w emulsions were used as templates in the production of both pH-responsive, surface-functionalised poly(methyl methacrylate) (PMMA) colloidal nanoparticles and non-responsive PMMA particles via an emulsion-solvent-evaporation technique. Lowering of the solution pH can trigger the reversible aggregation of these highly dispersed pH-responsive colloids into 3D structures with internal macroporosities dictated by the method of dehydration employed. The colloids can also co-encapsulate various hydrophobic molecules without any effect on particle stability and pH-responsiveness. The production of multi-responsive emulsion droplets via the encapsulation of oleophilic, magnetic Fe3O4 nanoparticles within a stable, surface-functionalised dodecane o/w emulsion was investigated. Droplet surface functionality allowed the formation of EE on lowering the pH, and encapsulated nanoparticles gave both the free-flowing and aggregated emulsions magnetic-responsiveness. The rate of aggregation and gel strength of multi-responsive EEs is compared to that of a standard pH-responsive emulsion.
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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.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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Junior, Agesinaldo Matos Silva. "Aplicação do ultrassom na coalescência de emulsões água em óleo." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-16122014-161035/.
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O processo de separação da água em emulsões de petróleo é feita durante o processamento primário do petróleo e consiste na coalescência de gotas de água. Para minimizar o uso de desemulsificantes e acelerar o processo de separação da emulsão alguns equipamentos podem ser utilizados como os separadores acústicos. Neste trabalho a técnica de força de radiação produzida por ondas estacionárias de ultrassom é aplicada na segregação das fases líquidas de emulsões água em óleo. São desenvolvidas células de ultrassom que operam em frequências próximas de 1 MHz através de ressonadores piezelétricos visando a aplicação na coalescência de gotas de água em emulsões do tipo água-óleo. O trabalho envolve simulações do campo acústico através de modelos analíticos unidimensionais e bidimensionais e de um modelo numérico bidimensional pelo método dos elementos finitos para o estado plano de deformações. São realizadas verificações experimentais em protótipos de células de alta potência para separação em batelada através da comparação do potencial de radiação acústica e da impedância elétrica com resultados de modelos computacionais. Diversos ensaios de quebra de emulsões sintetizadas de petróleo são realizados utilizando um aparato experimental de laboratório aplicando potências de até 600 W=l. Um sistema de controle de frequência de operação é implementado para manter máxima transmissão de potência elétrica para a célula. Os resultados mostraram que a técnica empregada pode reduzir pela metade o uso de desemulsificante químico (de 20 a 10 ppm) ou diminuir o tempo de residência em até 60% (de 20 para 8 min). Uma análise da influência da frequência na eficiência de desemulsificação é realizada e indica que não há sensibilidade no resultado para a faixa de frequência entre 0.8 e 1.5 MHz a uma temperatura ambiente de aproximadamente 23 C. A metodologia empregada auxilia no projeto das células e na aplicação da técnica, mas é insuficiente para explicar integralmente os mecanismos de separação e as diferenças entre o protótipo e o modelo. A aplicação de ultrassom na coalescência de emulsões possui potencial para desenvolvimento em larga escala.The oil water separation process of petroleum emulsions is performed during the primary processing of crude oil and consists of water droplets coalescence. To minimize the use of demulsifiers and accelerate the emulsion separation process some equipment may be used such as acoustic separators. In this work, a radiation force technique produced by ultrasound standing waves is applied to the water phase separation in oil emulsions. Ultrasound cells operating at ultrasonic frequencies near 1 MHz are developed using piezoelectric resonators applied to the coalescence of water droplets in oil emulsions. This work involves simulations of the acoustic field through one-dimensional and two-dimensional analytical models and a numerical model for two-dimensional plane strain finite element analysis. Furthermore, experimental verification is performed using high power prototypes for batch separation by comparing the acoustic radiation potential and electrical impedance with computational models results. Several tests of synthesized petroleum emulsions breaking are performed using an experimental laboratory apparatus applying up to 600 W=l. A frequency control system is implemented in order to maintain maximum electric power transmission to the cells. The results showed that the technique can halve the use of chemical demulsifier (from 20 to 10 ppm) or decrease the residence time of up to 60% (from 20 to 8 min). An analysis of the frequency influence on demulsification efficiency is performed and indicates that there is no parameter sensitivity in the frequency range between 0.8 and 1.5 MHz at room temperature of approximately 23 C. It is demonstrated that the design methodology is consistent and the application has potential for large-scale development.
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Wong, Susanna Wing Man. "Microdisk fabrication by emulsion evaporation." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/6006.
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Colloidal suspensions of disk-like particles have been of interest in both colloidal and liquid crystal studies because they exhibit unique liquid crystalline phases different from those of rod-like molecules. Disk-like particles, such as asphaltenes in heavy oil industry, clay particles in agriculture, and red blood cells in biology, are of great interest in a variety of industries and scientific areas. However, to fabricate monodisperse microdisks, uniform in structure or composition with precise control of particle size and shape has not yet succeeded. In this thesis, we show an experimental strategy of using microfluidic technique to fabricate homogeneous ñ-eicosene microemulsions with chloroform in an aqueous solution of sodium dedecyl sulfate (SDS). The monodisperse chloroform emulsions, generated by the glass-based microfluidic devices, ensure the precise control on microdisk particle size and shape. A systematic investigation was performed to study the relation between the resulted microdisk size and the initial concentration of ñ-eicosene in chloroform before evaporation. The smectic liquid crystalline phase inside the wax particles controls the coin-like disk shape below the melting temperature of waxâÂÂs rotator phase. The kinetics of the disk formation is observed using a polarized light microscope. Dynamic light scattering is used to characterize the Brownian motion of the microdisks, and the rotational diffusion is estimated from the image sequences taken by the charge-coupled device (CCD) camera. Effort has been put into collecting a large quantity of microdisks to investigate the discotic liquid crystalline phases, which can be readily probed by light scattering and microscope. In comparison, X-ray and neutron have to be used for the atomic liquid crystalline phase investigation.
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Shoaf, Glenn Lewis. "Emulsion copolymerization with carboxylic acids." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/10255.
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Mead, Richard Norman. "Emulsion copolymerization in continuous reactors." Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/11030.
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Campanelli, John R. "Interfacial viscosity and emulsion stability." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63776.
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BASTIDAS, TERESA JULIET PENA. "EMULSION GENERATION DURING OIL PRODUCTION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=11322@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOA presença de emulsões durante a produção de óleo causa vários problemas e traz desafios tecnológicos a serem vencidos, já que afeta a produtividade dos poços, a elevação artificial, o tempo de vida dos equipamentos e o processo de separação do óleo produzido. Existe incerteza em relação à origem das emulsões geradas durante a produção de petróleo, podendo resultar do escoamento no meio poroso, do fluxo turbulento no fundo do poço, nas bombas, ou nas instalações de superfície. Este trabalho é focado na geração de emulsões no meio poroso e em alguns aspectos das emulsões produzidas em escoamentos turbulentos. Emulsões podem ser formadas no escoamento bifásico em um meio poroso através de diversos mecanismos. A quebra de gotas da fase não molhante durante a passagem por uma garganta é um dos mecanismos mais importantes. Este fenômeno foi estudado em detalhe através da visualização do escoamento de grandes gotas de óleo suspensas em água através de uma garganta de poro. Foi obtido o mapeamento numa única curva das condições que levam à quebra de gota dentro de um capilar com garganta. Os resultados obtidos determinam as condições nas quais o processo de emulsificação ocorre em um meio poroso. O estudo de geração de emulsões no escoamento turbulento foi focado no estudo do tipo de emulsão (distribuição de tamanho de gotas e fase externa) obtida através de mistura de óleo e água em um misturador, em função da concentração e propriedades das fases. Especial atenção é dada às condições necessárias para a inversão da fase externa e formação de água livre. Os resultados obtidos permitem conhecer a influência das propriedades e concentração das fases no tipo de emulsão produzida, alem de proporcionar ferramentas que permitem o monitoramento remoto da morfologia das emulsões que escoam em algum ponto específico dos processos de produção, desde o fundo de poço até as instalações de superfície.
Emulsion formation during oil production may take place in the flow inside the reservoir or in the two-phase flow down hole in production wells, and through pipelines and valves in surface facilities. Emulsions can cause a number of operational problems such as tripping of equipment in gas-oil separations plants and high pressure drops in flow lines. Flow conditions responsible for generation of emulsions present at the surface, going from porous media, turbulence down hole, through pumps, or in surface facilities, are uncertain, and their effects on the drop size, are not well understood. The present work is focused on emulsion generation inside reservoirs and in some aspects of the produced emulsions in turbulent flow. Emulsions can be formed in the two-phase flow inside a porous media by different mechanism. Snap-off of the non-wetting phase drops as there flow through pore throats is one of these mechanisms. This phenomenon is analyzed in this work by visualizing the flow of large oil drops suspended in water through a glass micro-capillary with a constriction. The conditions at which the snap-off occurs were mapped as a function of the operating parameters. The results define the conditions at which emulsification by snap-off occurs inside a porous media. Study of emulsion formation in a turbulent flow was focused on the characteristics of the produced emulsion (external phase and diameter size distribution) as a function of the phase concentration and properties. Conditions for emulsion inversion were analyzed as a function of the phases properties and concentration. The results can be used to estimate the state of emulsification as a function of process conditions at different locations, from the reservoir to the surface facilities.
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Potyka, Ingrid. "Emulsion-formulation of microbial herbicides." Thesis, University of Bristol, 1995. http://hdl.handle.net/1983/618a10ab-a6e4-49c4-bf4c-1b3c343c4135.
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Development of microbial herbicides is constrained by unreliability in the field where conditions are often sub-optimal for infection. Crucially, sufficient moisture, often dew, is required to establish infection. Two model systems, Colletotrichum dematium (Pers. ex Fr. ) Grove on Chenopodium album L. and Mycocentrospora acerina (Hartig) Deighton on Viola arvensis Murr., have been investigated and formulation requirements for each system identified, principally to reduce the dew period necessary for infection. Effects of adjuvants (surfactants, stickers and humectants) on spore germination and appressorium formation were investigated in vitro. Few were toxic and then, principally, at high concentration. The surfactants Tween 40,60 and 80 were compatible with both pathogens. Similarly, the stickers acacia, ghatti, guar, karaya, locust bean and xanthan gums and low viscosity alginic acid were all non-toxic as was the humectant glycerol. Each pathogen reacted differently to the adjuvants and any potential microbial herbicide will need individual matching of adjuvants to give an effective formulation. A working formulation (rapeseed oil-in-water (1: 10 v/v) emulsion using 0.1 % v/v Tween 40 as the emulsifier) was found to reduce the dew period requirement of M. acerina from 36 to 18 hours. The formulation protected spores from desiccation for 24 hours after application, or for 16 hours following a sub-optimum dew period occurring immediately after application. Scanning electron microscopy showed that the applied spores, and the developing mycelium, were immersed in the oil deposit. Transmission electron microscopy of sections through formulation deposits on the leaf revealed that some inversion of the emulsion, to form a water-inoil deposit, had occurred, suggesting a mechanism of protection against desiccation. The oil phase infiltrated the cortical intercellular spaces only when the leaf was infected. This intercellular oil contained more water than that on the leaf surface. Emulsion-formulation applied to run-off with an 'air brush', consistently gave significantly better weed control under sub-optimal dew conditions than a formulation of surfactant only. When applied with a conventional hydraulic nozzle at 400 1 ha" the emulsion was only occasionally superior to the surfactant alone. Such interactions require further in-depth investigation. The importance of correct inoculum placement for maximum effectiveness, independent of formulation type, was highlighted. Unless all meristems are killed, survivors quickly grow, despite the death of neighbouring leaves and petioles, and the weed suffers merely a growth check. Formulation as emulsion improved diseasee stablishmenta nd diseasee xpressioni n the target weedo nly in somec ircumstancesF. urther researchin to spraya pplicationm ethodsa ndt heir interactions with formulation, host and environment is clearly necessary
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Brunier, Barthélémy. "Modeling of Pickering Emulsion Polymerization." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10320/document.
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L’objectif du présent projet est de développer une méthodologie pour la modélisation fondamentale de procédés de polymérisation en émulsion sans tensioactif stabilisés par des particules inorganiques, dénommées "polymérisation en émulsion Pickering". La modélisation des systèmes de polymérisation en émulsion nécessite la modélisation de la distribution de taille des particules (PSD), qui est une propriété importante d'utilisation finale du latex. Cette PSD comprend des sous-modèles dédiés à la nucléation des particules, le transfert de masse entre les différentes phases (monomère, radicaux, stabilisant) et la coagulation des particules. Ces modèles devraient de préférence être validés expérimentalement de manière individuelle. La première partie principale du travail est consacrée à l'étude expérimentale. Cette partie peut être divisée en trois parties. La première partie décrit l'adsorption de particules inorganiques sur le polymère sans réaction. Une adsorption multicouche a été observée et l’isotherme B.E.T. a été capable de décrire cette adsorption. L'adsorption se révèle être plus importante pour une force ionique plus élevée. La dynamique d'adsorption semple être rapide et par conséquent le partage peut être considéré à l'équilibre pendant la polymérisation. La deuxième partie concerne l'étude de différents paramètres de réaction sur le nombre de particules et la vitesse de réaction dans des polymérisations ab initio. L'effet du mélange, de la concentration initiale des monomères et de la concentration de l'initiateur a été étudié. L'optimisation de ces conditions a été utile pour la partie de modélisation. La dernière partie décrit les différences entre plusieurs Laponite® à travers la polymérisation en émulsion ab initio du styrène.La deuxième partie principale du manuscrit a porté sur la modélisation de la polymérisation en émulsion Pickering. Le modèle de bilan de population et le nombre moyen de radicaux par particule ont été calculés en fonction de l'effet des particules organiques. La croissance des particules de polymère a été optimisée en ajustant les modèles d'entrée et de désorption des radicaux décrits dans la littérature aux données expérimentales. Aucune modification n'a été nécessaire, ce qui nous a permis de conclure que l'argile n'avait aucune influence sur l'échange radical. Cependant, la stabilisation joue un rôle important dans la production de particules de polymère. Le modèle de nucléation coagulante a été capable de décrire le taux de nucléation et de prédire le nombre total de particulesThe aim of the present project is to develop a methodology for fundamental modeling of surfactant-free emulsion polymerization processes stabilized by inorganic particles, referred to as “Pickering emulsion polymerization”. Modeling emulsion polymerization systems requires modeling the particle size distribution (PSD), which is an important end-use property of the latex. This PSD includes submodels dedicated to particle nucleation, mass transfer between the different phases (monomer, radicals, stabilizer), and particle coagulation. These models should preferably be individually identified and validated experimentally. The first main part of the work is dedicated to the experimental study. This part can be divided in three parts. The first part describes the adsorption of inorganic particles on polymer without reaction. Multilayer adsorption was observed and B.E.T. isotherm was able to describe this adsorption. The adsorption was found to be enhanced at higher ionic strength. The adsorption dynamics were found fast and therefore clay partitioning can be considered at equilibrium during polymerization. The second part concerned the investigation of different reaction parameters on the particles number and reaction rate in ab initio polymerizations. The effect of mixing, initial monomer concentration and initiator concentration were considered. Optimization of these conditions was useful for the modeling part. The last part described the differences between several LaponiteR_ grades through the ab initio emulsion polymerization of styrene. The second main part of the manuscript focused on the modeling of the Pickering emulsion polymerization. The population balance model and average number of radicals balance were adapted regarding the effect of inxi organic particles. The growth of the polymer particles was optimized by fitting the models of radicals’ entry and desorption described available in literature to the experimental data. No modification was needed, which allowed us to conclude that the clay had no influence on radical exchange. However, LaponiteR_ stabilization played an important role in polymer particles production. Coagulative nucleation model was able to describe the nucleation rate and predict the total number of particles
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Wang, Hongzhi. "Understanding of charge effects in pickering emulsions and design of double pickering emulsion templated composite microcapsules." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52965.
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Particle stabilized emulsions, also known as Pickering emulsions, have been widely used in many industry applications. While the breadth of potential applications for Pickering emulsions keeps growing, our fundamental understanding of Pickering emulsions is still poor. My thesis work addresses both fundamentals and applications of particle stabilized emulsions. In the fundamental part of this thesis work, we investigated the effects of particle charge on particle adsorption and the particle contact angle, and to investigate their ensuing consequences for the stability of Pickering emulsions. We provided the first experimental hint that the widely overlooked image charge repulsion can hinder the adsorption of particle to the oil-water interface and prevent the formation of Pickering emulsions. Consistently with the experimental suggestion, our theoretical model also confirmed that the image charge repulsion has the right order of magnitude, relative to the other forces acting on the particle, to impede particle adsorption and Pickering emulsification. For the conditions in which particle adsorption to the liquid interface does occur, the particle contact angle will play an important role in influencing the stability and type of Pickering emulsions. Our experimental work showed that the equilibrium contact angle of particles at interfaces and the type of emulsions preferentially stabilized by these particles can be strongly affected by the particles' charging state, which we attribute to a free energy contribution from the electric field set up by the charged particle and its asymmetric counterion cloud. A very simplistic calculation considering only the dipole field as the leading contribution and treating the water phase as a perfect conductor, found that the energy stored in the field is indeed strong enough and shows sufficient variation with the particle position to shift the equilibrium position significantly from where it would be based on interfacial tension alone. In a separate, more application oriented part of this thesis work, we have fabricated microcapsules from double Pickering emulsions and demonstrated that the combined use of hard silica particles and pH-responsive dissoluble polymer particles at the emulsion interface imparts a combination of pH-responsiveness (stimulated pore opening) and structural integrity to resulting capsules. We have further demonstrated the first double Pickering emulsion templated capsules in which interfacial polymerization was carried out at both emulsion interfaces, yielding a capsule with two composite shells, composed of polyurethane and silica particles, and characterized the transport of a model cargo through the capsules walls as well as the capsules' mechanical properties.
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Desai, Chiragkumar Narendra Prasad. "Development and stability of pharmaceutical emulsions: influence of physicochemical factors on stability of emulsion and bioavailability." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/1632.
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Lamba, Michael A. S. "Radiation Dose Mapping Using Magnetic Resonance Imaging in a Superheated Emulsion Chamber." University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin962393412.
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Nietgen, Maria. "Bildung und Zerfall von Silberclustern bei Mikrokristallen fotografischer AgCI-Emulsionen nach der Belichtung in Abhängigkeit von Kristalleigenschaften und äusseren Faktoren." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=964463512.
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Villamagna, Fortunato. "Modelling of interfaces in emulsion explosives." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39313.
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An energy optimised Tree Branch Methodology was developed to overcome the multiple minima problem in molecular mechanics calculations of acyclic molecules. Target molecules were assembled one heavy atom at a time from small precursors, and the energy minimized after each addition. The number of structures to be minimised was significantly reduced by following the lowest energy path in the Tree Branch Method. Comparison of the calculated configurations to minimum energy structures obtained from complete conformational search is made.The compression of fatty acid monolayers in Langmuir-Blodgett trough experiments at the air/water interface was modelled using a two dimensional array. The minimum energy configuration of the acids was obtained using the Tree Branch Methodology, and the water coordination number determined by comparison of calculated and experimentally measured dipole moments. The variation in measured dipole moments as the hydrated head group was compressed were explained.
Minimum energy configurations of known surfactant molecules used in the preparation of water-in-oil emulsion explosives were obtained through the Tree Branch Methodology, and the optimised geometries used to calculate structural parameters assuming standard van der Waals radii around each atom. Comparison of the structural parameters to the stability of the emulsions in which the surfactants were used, allowed preliminary structural criteria to be established. Based on the structural criteria, a number of new families of surfactant head group were designed, and preliminary rules for matching head to tail group combinations proposed.
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James, M. I. "Emulsion polymerisation of vinylidene chloride copolymers." Thesis, Lancaster University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235213.
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Lu, Jian Ren. "The surface chemistry of emulsion breakdown." Thesis, University of Hull, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384850.
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O'Donnell, John Patrick. "Catalytic chain transfer in emulsion polymerisation." Thesis, University of Warwick, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300718.
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Nicholson, Catherine Emma. "Crystallisation in emulsion and microemulsion systems." Thesis, Durham University, 2006. http://etheses.dur.ac.uk/1298/.
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The use of emulsions as an aid to the study of crystallisation has long been known. However, the exploitation of this technique has not yet been realised to its full potential. The various conditions that can be generated at, or near, an interfacial region provide a wide range of possibilities for the controL and probing of crystallisation mechanisms. In this thesis, the effect of the interfacial curvature is considered for the case of ice crystallisation within water-in-oil emulsions. The use of a known ice nucleator, heptacosanol, acting as a co-surfactant enables the effect of a reduced epitaxial match to be monitored, with decreasing water pool diameter. The extreme case where the water pool does not contain enough material to form a crystalline nucleus such that ~G ~ 0 on complete crystallisation is found. This demonstrates for the first time that a direct experimental measurement of the critical nucleus size is possible. The use of non-ionic surfactants allows emulsions to phase invert from water-in-oil to oil-in-water upon cooling, and on passing through the phase inversion, ultra low interfacial tensions are obtained. At the phase inversion, crystallisation by the surfactant layer is found to be greatly inhibited, even at high solute supersaturations for glycine and L-asparagine emulsions. Hence we achieve anomalous crystallization behaviour, with crystallisation achieved both on cooling and heating from the same system. Another unique effect characterised is that of oil droplet inclusion into a single crystal. The highly polar octanoic acid oil phase adheres to the growing glycine crystal so strongly that crystal growth proceeds around the droplet without disruption to the overall resulting crystal to produce macroporous crystals. Where growth rates are uneven, highly fenestrated single crystalline structures result. Upon reducing the oil droplet diameter, dendritic morphologies, highly unusual for such low supersaturations of glycine, are formed. Moreover, the surfactant mixture also controls the polymorph produced, and reproducibly yields the desired ~-glycine form.
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French, David James. "Fundamental aspects of Pickering emulsion stabilisation." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/20450.
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Much research has been carried out in recent years on Pickering emulsions, but understanding of the underlying physics requires considerable strengthening. This thesis seeks to address several fundamental aspects by presenting the results of recent experimental work. This work has focused on a model oil-in-water emulsion system stabilised by fluorescent colloidal silica particles and using a mixture of dodecane and isopropyl myristate as the oil phase. The phase behaviour of the particle dispersions has been altered using sodium chloride and sodium iodide, whilst sodium hydroxide and hydrochloric acid have been used to adjust the pH of samples. Comparisons are also made to emulsions stabilised by commercially available fumed silica. Conventionally, it was assumed that a weakly flocculating particle dispersion is required in order to generate a stable Pickering emulsion. It is shown in this work, however, that in some circumstances a weakly flocculating dispersion leads to the least stable emulsion. It is therefore argued that a more nuanced view of Pickering stabilisation is required, taking into account the factors affecting whether particles will adsorb to the interface during emulsification. Very recently it has begun to be suspected that Pickering emulsions sometimes aggregate due to the sharing of particles between two droplets, an effect known as bridging. In this thesis it is also shown that particle bridges can form in Pickering emulsions at high shear, and that they can subsequently be broken by low shear or by modifying the particle wettability. For the first time, electron microscopy has been used to provide direct evidence of droplets sharing particles. A simple theoretical model is developed, based on collisions between partially coated droplets, which captures the trends observed experimentally. It is argued that particle bridging may have been overlooked in the literature, and that the shear history of emulsions is a crucial determinant of subsequent behaviour. The deaggregation of bridged emulsions has been studied using a novel method where two different colours of particles are used. By starting with two emulsions which are bridged, each stabilised by a different colour of particle, and then using confocal microscopy to study them as they are mixed together and deaggregate, the processes involved in deaggregation can be elucidated. These experiments have also shown, for the first time, the dynamic nature of particles in Pickering emulsions; particles transfer readily between droplets when the samples are placed on a roller bank. It is found that a period of unbridging and rebridging takes place prior to deaggregation of the emulsions, and the timescale of deaggregation can be tuned by varying the particle wettability. The two-colour method has also been applied to the study of Pickering emulsions which are repeatedly sheared. It is found that limited coalescence is not reestablished simply by re-applying the shear rate which was used in the initial emulsification. This behaviour is attributed to the presence of an elastic shell of particles at the interface, which inhibits droplet breakup, and is in contrast to that of surfactant-stabilised emulsions, where increasing the stabiliser concentration makes droplets more liable to deform and breakup. Finally, a short study has been carried out attempting to increase the scale of the experiments presented in this thesis to sample volumes of approximately one litre. This study has demonstrated the relevance of particle bridging to industrial emulsification processes. Overall, experiments with carefully controlled model Pickering emulsions, including those using two colours of particles, have revealed the fundamental workings of these arrested systems.
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DE, GUNZBOURG ANEMONE. "Polymerisation anionique de l'octamethylcyclotetrasiloxane en emulsion." Paris 6, 1993. http://www.theses.fr/1993PA066562.
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L'objectif de notre travail a consiste a etudier de facon approfondie la polymerisation anionique de l'octamethylcyclotetrasiloxane en emulsion aqueuse. La presentation de ce travail comporte tout d'abord une analyse bibliographique concernant d'une part, la synthese des polysiloxanes par polymerisation et polycondensation, et d'autre part, les differents aspects concernant les emulsions et les polymerisations dans ces milieux. Les techniques experimentales utilisees sont presentees a la suite. La partie principale de ce travail decrit dans un premier temps les essais relatifs a la determination des conditions optimales de polymerisation (vitesse reactionnelle, stabilite de l'emulsion). Les meilleurs resultats ont ete obtenus en utilisant un agent emulsifiant-amorceur: l'hydroxyde de n-benzyl-n,n-dimethyldodecylammonium. Nous avons pu montrer que cette methode permet d'obtenir de facon tres simple des dihydroxypolysiloxanes lineaires, de masse molaire controlee, d'indice de polymolecularite faible, avec des rendements importants. Dans un second temps, une etude de la cinetique, des produits formes et des caracteristiques des emulsions nous a permis de montrer que l'ensemble des reactions (amorcage, propagation, polycondensation, redistribution intra- et intermoleculaires et terminaison reversible) interviendraient majoritairement a l'interface huile/eau. Le facteur principal controlant la reaction serait la surface totale du systeme particulaire (et donc la presence des cations ammoniumquaternaires emulsifiants). Nous avons pu determiner par ailleurs les constantes de vitesse des differentes reactions mises en jeu
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Billuart, Guilhem. "Free radical emulsion polymerization of ethylene." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10033.
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Les travaux présentés dans cette thèse portent sur la polymérisation radicalaire de l'éthylène en émulsion, dans des conditions douces (P < 250 bar et T < 90 °C). Tout d'abord, l'homopolymérisation de l'éthylène a été étudiée. Des latex stables de polyéthylène présentant des taux de solide relativement élevés (30 %) ont été obtenus. Pour cela, deux systèmes différents d'amorçage et de stabilisation (cationique et anionique) ont été employés. Ces latex peuvent trouver des applications comme revêtements hydrophobes (par exemple du papier). L'étude des propriétés thermiques des latex a mis en évidence des phénomènes de cristallisation du polyéthylène à basse température, dû à son confinement dans les nanoparticules. Cela a une forte influence sur les morphologies finales des particules. D'autre part, la copolymérisation radicalaire de l'éthylène en émulsion a été étudiée. Les comonomères utilisés sont le styrène, l'acrylate de butyle, le méthacrylate de méthyle et l'acétate de vinyle qui différent par leur solubilité dans l'eau et leurs rapports de réactivité de copolymérisation avec l'éthylène. La composition des copolymères obtenus influence leurs propriétés thermiques (Tg, Tf). Des latex stables de copolymères de compositions variées ont pu ainsi être synthétisés. Ce travail en homo- et copolymérisation a souligné la complexité des milieux de polymérisation en émulsion impliquant un monomère gazeux supercritique comme l'éthylèneIn this work, the free radical emulsion polymerization of ethylene under mild conditions (P < 250 bar and T < 90 °C) was investigated. Ethylene homopolymerization was first studied. Stable polyethylene latexes of significantly high solids content (30 %) were produced. This was achieved by the use of two different initiating and stabilizing systems (cationic and anionic). These latexes could be applied as hydrophobic coatings (e.g. on paper). Investigation of the thermal properties of the latexes evidenced crystallization phenomena at low temperatures, owing to PE confinement in the nanoparticles, which strongly impacted their final morphologies. Free radical emulsion copolymerization of ethylene was then studied. The investigated comonomers were styrene, butyl acrylate, methyl methacrylate and vinyl acetate. They differ in their reactivity ratios to ethylene and their water solubility. The composition of the obtained copolymers had a strong influence on their thermal properties (Tg, Tm). Stable latexes containing copolymers of various compositions were thus synthesized. This work on homo- and copolymerization evidenced the complexity of the polymerization media involving a gaseous supercritical monomer such as ethylene
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Sunkel, Jorge Max. "The behavior of sol-emulsion systems /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/9927.
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De, Bruyn Hank. "The Emulsion Polymerization of Vinyl Acetate." Thesis, The University of Sydney, 1999. http://hdl.handle.net/2123/381.
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Abstract This work investigates the kinetics of the emulsion polymerization of vinyl acetate. Several aspects of this system have been clarified, including the induced decomposition of persulfate, retardation by oxygen and entry by, and analysis of, the aqueous phase oligomeric radicals. It has been shown that the retardation period observed in the emulsion polymerization of VAc can be explained by the effect of traces of oxygen (< 10-6 M) on the entry efficiency of the initiator-derived aqueous-phase oligomeric radicals. Comparison of rates of polymerization in V and persulfate -initiated polymerizations together with electrospray mass spectrometry of aqueous phase oligomers, has shown that the mechanism for the induced decomposition of persulfate by vinyl acetate is chain transfer to initiator from aqueous-phase oligomeric radicals. A value has been determined for the rate coefficient for transfer to initiator, by fitting literature data to a model based on this mechanism. The reported independence of the rate of polymerization from the monomer concentration in the emulsion polymerization of vinyl acetate has been investigated. Possible explanations for this behaviour have been proposed and tested in this work, by measuring radical-loss rates directly with y-relaxation techniques. Although the Y relaxations were found to be affected by experimental artefacts, it has been demonstrated that rapid exit is not responsible for the high radical-loss rates in this system. The major artefact identified in the y relaxations was the significant effect of relatively small exotherms on relaxation behaviour, Methodologies were developed for correcting affected data and for avoiding exotherms under certain conditions. Arrhenius parameters were determined for the rate coefficient for chain transfer to monomer using the In^M method, which utilises the whole MWD. This section of the work is incomplete, for reasons detailed in chapter 5. However, as a preliminary indication it was found that the frequency factor was 106.38 M-1 s-1 and the activation energy was 38.8 kJ mol-1.
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De, Bruyn Hank. "The Emulsion Polymerization of Vinyl Acetate." University of Sydney, Chemistry, 1999. http://hdl.handle.net/2123/381.
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Abstract This work investigates the kinetics of the emulsion polymerization of vinyl acetate. Several aspects of this system have been clarified, including the induced decomposition of persulfate, retardation by oxygen and entry by, and analysis of, the aqueous phase oligomeric radicals. It has been shown that the retardation period observed in the emulsion polymerization of VAc can be explained by the effect of traces of oxygen (< 10-6 M) on the entry efficiency of the initiator-derived aqueous-phase oligomeric radicals. Comparison of rates of polymerization in V and persulfate -initiated polymerizations together with electrospray mass spectrometry of aqueous phase oligomers, has shown that the mechanism for the induced decomposition of persulfate by vinyl acetate is chain transfer to initiator from aqueous-phase oligomeric radicals. A value has been determined for the rate coefficient for transfer to initiator, by fitting literature data to a model based on this mechanism. The reported independence of the rate of polymerization from the monomer concentration in the emulsion polymerization of vinyl acetate has been investigated. Possible explanations for this behaviour have been proposed and tested in this work, by measuring radical-loss rates directly with y-relaxation techniques. Although the Y relaxations were found to be affected by experimental artefacts, it has been demonstrated that rapid exit is not responsible for the high radical-loss rates in this system. The major artefact identified in the y relaxations was the significant effect of relatively small exotherms on relaxation behaviour, Methodologies were developed for correcting affected data and for avoiding exotherms under certain conditions. Arrhenius parameters were determined for the rate coefficient for chain transfer to monomer using the In^M method, which utilises the whole MWD. This section of the work is incomplete, for reasons detailed in chapter 5. However, as a preliminary indication it was found that the frequency factor was 106.38 M-1 s-1 and the activation energy was 38.8 kJ mol-1.
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Jauregui, Daisy. "Synthesis and Optimization of Emulsion Polymers." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1533.
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Synthetic latex or resin is perhaps the most important component of any paint formulation. As the binder, it holds all ingredients in a paint together and is responsible for film formation. Various latexes are used in industry though acrylic resins have shown to impart superior paint properties.This project is concerned with the synthesis of an acrylic latex. Various emulsion polymerization processes were used including semi-batch, starved-feed, and in-situ seeded in the attempt to produce a stable latex that can be used in a broader study concerning the syneresis and rheology mechanisms of latex/thickener systems. In addition, this project investigates the optimization of the emulsion polymerization teaching lab used in the Polymers and Coatings masters program. Here, a batch emulsion polymerization process was studied and various particle stability aspects altered to produce a stable latex with minimum coagulum.
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Cervantes, de la rosa Abigail. "Macroscopic modeling in double emulsion systems." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC056/document.
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Les procédés de séparation à l’aide de membranes liquides sous forme d’émulsions doubles (DE) ont fait l’objet d’un examen approfondi en vue d’applications potentielles dans des domaines tels que la récupération des métaux, la séparation des gaz, l’élimination des composés organiques, l’élimination des polluants et les bioséparations. Les difficultés d’application de ces procédés ne concernent pas le caractère sophistiqué des équipements ou des installations, mais réside plutôt dans une bonne compréhension des phénomènes complexes qui se produisent à l’intérieur de ces systèmes. Depuis leur invention, d’importants efforts ont permis d’améliorer la modélisation des procédés de séparation par émulsions doubles. Toutefois, une représentation mathématique détaillée des phénomènes de diffusion/réaction au sein de ces systèmes restait inachevée. C’est pourquoi, l’objectif de cette thèse est de décrire le transport réactif d’un soluté au sein d’une émulsion double, constituée de trois phases, au moyen d’une modélisation permettant d’intégrer à l’échelle macroscopique les mécanismes aux échelles locales. La méthode de prise de moyenne volumique est utilisée pour établir rigoureusement les équations à l’échelle d’un continu équivalent dans le contexte des transferts hors équilibre massique local (NLME). La modélisation proposée dans ce travail repose sur deux philosophies distinctes. Dans un premier temps, les DES sont considérées comme des systèmes constitués par trois phases où les changements de concentration dans chacune d’entre-elles se produisent à la même échelle de longueur. Dans un deuxième temps, les DES correspondent à deux régions homogènes où les changements de concentration se produisent à deux échelles de longueur différentes. Deux modèles macroscopiques différents sont ainsi obtenus : le modèle à trois phases et celui à deux régions. Dans les deux cas, ces modèles font intervenir les coefficients effectifs de transport comprenant l’information aux petites échelles. Ces derniers sont liés aux variables de fermeture dont la détermination est obtenue par la résolution des problèmes de fermeture associés. Enfin, une analyse d’un procédé de séparation par contact dans un réservoir agité a été effectuée en appliquant les deux modèlesLiquid membrane separations as Double Emulsions (DE) have been extensively examined for potential application in fields such as metal recovery, gas separation, organic compound removal, pollutant removal, and bioseparations. The difficulties in the application of these processes do not consist in sophisticated equipment or installation but in a good understanding of the complex phenomena that occur inside these systems. Since its invention, efforts have been made for successful modeling of DE process separation; however, information about the diffusion and reaction phenomena inside the DE has not been included in the mathematical descriptions in detail yet. Therefore, the objective of this thesis is to describe the solute transport with chemical reaction through DE systems by means of rigorous modeling that can provide with valuable information from the micro-scale to be applied at the macro-scale.To accomplish this, a DE system has been analyzed as a three-phase system characterized by more than one disparate length scales.The method of volume averaging has been used to derive rigorous averaged equations in the context of the non-local mass equilibrium (NLME). The structure of the DES has been studied from two different perspectives: 1) the DES as a single domain where concentration changes occur in the same length scale and 2) the DES consists in two homogeneous regions where concentration changes occur at two different length scales. As a result of these different standpoints of representing the system, two different averaged macroscopic models were obtained: the three-phase and the two-region models. Both models present effective coefficients that include information about the micro-scale. These latter are related to closure variables which are solutions of associated boundary-value problems. Finally, an analysis of a DE-containing separation process in a stirred tank by applying both models was made
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Teipel, Ulrich. "Rheologisches Verhalten von Emulsionen und Tensidlösungen /." Stuttgart : Fraunhofer-IRB-Verl, 1999. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=008742627&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Huang, Xiaoqing. "Evaluation of hydrocolloid gums as stabilizers in oil/water emulsion, emulsion stability, interfacial activity and rheological properties." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0018/MQ55681.pdf.
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Dabrowski, Miriam Lucia [Verfasser], and Cosima [Akademischer Betreuer] Stubenrauch. "Tailor-made methacrylate-based polymer foams via emulsion and foamed emulsion templating / Miriam Lucia Dabrowski ; Betreuer: Cosima Stubenrauch." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2020. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-ds-117101.
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Leonardo, Marcelo Fábio. "Modelagem matemática do processo de copolimerização em emulsão de acrilato de butila e acetato de vinila." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-02092011-134741/.
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Materiais poliméricos são amplamente utilizados e, atualmente, especificações mais rígidas para aplicações especiais tem sido impostas a esses materiais. A microestrutura, em geral, exerce intensa influência na determinação das propriedades macroscópicas dos materiais, sendo assim, o controle da microestrutura e seu relacionamento com essas propriedades é de interesse estratégico. Modelos matemáticos dos processos de polimerização são importantes para relacionar as variáveis de processo com a produtividade e a microestrutura do polímero. Neste trabalho um modelo matemático do processo de copolimerização em emulsão do acrilato de butila com o acetato de vinila foi elaborado. O modelo matemático gerado constitui-se num sistema que engloba equações algébricas (p.ex., de equilíbrio de fases) e diferenciais ordinárias de primeira ordem (p.ex., os balanços de massa dos componentes), num conjunto algébrico diferencial não linear de primeira ordem (DAE). Esse sistema foi solucionado numericamente utilizando-se, tanto o método BDF (backward differentiation formulas) quanto as NDF (numerical differentiation formulas), implementado em MATLAB 6.5R13; mais especificamente, obtiveram-se bons resultados utilizando-se a ode113. Os resultados mostram que o modelo representa razoavelmente bem os dados experimentais de trabalhos anteriores do grupo de pesquisa, embora um dos três parâmetros de identificação do modelo tenha sido penalizado com valores abaixo daqueles geralmente reportados na literatura. Apesar disso, o modelo mostrou-se funcional e pode ser útil na simulação do processo. Perfis polinomiais de variações temporais de temperatura também foram aplicados na etapa de otimização simples dos parâmetros das equações desses perfis, objetivando melhorias (redução) no tempo de reação. Observou-se, todavia, que o sistema DAE é de implementação complicada e requer cuidados adicionais na etapa de geração da inicialização consistente e de atribuição dos valores iniciais dos parâmetros do modelo, assim como tende a manifestar complicações na etapa de identificação do modelo.Polimeric materials have been largely used and, today, more stringent specifications have been imposed to these materials for special applications. In general, microstructure exercises intense influence on the macroscopic properties of the polymer: therefore, the control of the microstructure and its relation with these properties is of strategic interest. Mathematical models of the polymerization processes are important tools to predict the effect of process variables with the process productivity and the polymer microstructure. In this work a mathematical model of the emulsion copolymerization process of butyl acrylate and vinyl acetate was elaborated. The resulting model is a system of DAE (differential algebraic equations) and was solved numerically using the function ode113 of the software MATLAB6.5R13, employing both BDF (backward differentiation formulas) and NDF (numerical differentiation formulas) methods. The results show that the model is able to represent reasonably well the experimental data taken from previous works of the research group, although one of the three identification parameters had been adjusted to values lower than those reported in the literature. Nevertheless, the model is functional and can be useful for process simulation. Polynomial curves of temperature versus time variations were also studied for optimizing the polynomial coefficients, seeking the improvement (reduction) of the reaction time. However, it was observed that DAE implementation is complicated and demands further careful procedures for generating consistent initialization conditions for attributing good initial values for the model parameters, presenting difficulties in the model identification step.
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Giannini, Hélio. "Polimerização em emulsão de estireno em microrreator." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-30062016-090801/.
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A polimerização em emulsão de estireno em um microrreator Syrris de 250 µL com misturador estático junção \"T\" foi estudada em duas etapas. Primeiro somente a fluidodinâmica deste dispositivo não convencional foi avaliada, depois, foi desenvolvida a reação de polimerização de forma a observar como este fator influencia no sistema. Os experimentos foram realizados procurando se atingir maiores conversões, mas mantendo a estabilidade da emulsão. Foi um trabalho exploratório, portanto se assemelha mais a um processo de evolução (evolutionary process). Foram verificados a partir de qual relação das vazões dos dois fluidos ocorre a formação de gotas, e que com o aumento da vazão da fase contínua, aquosa (Qc), mantendo constante a vazão da fase dispersa (Qd), foi verificado uma diminuição do diâmetro das gotas e um regime de fluxo laminar. Posteriormente, realizou-se a polimerização em emulsão do estireno no microrreator, porém com restrições para altas vazões. Os parâmetros de processo testados foram a proporção Qc e Qd, a temperatura e a concentração do iniciador para então verificar o efeito que a variação destas ocasionam na conversão de monômero, no diâmetro e número de partículas e nas massas moleculares médias. A polimerização foi feita para soma das vazões Qc e Qd da ordem de 100 µ L/min, com 15% de monômero na formulação e com o maior tempo de residência possível de 2,5 minutos. Para maiores concentrações de monômero, acima de 15% foi verificado entupimento do canal do microrreator. A taxa de conversão de monômero aumentou com o aumento da temperatura e com o aumento da concentração do iniciador, mas o maior valor atingido foi de apenas 37% devido ao baixo tempo de residência. Nos casos de maiores taxas de conversão, as massas moleculares obtidas foram as menores conforme o esperado pela teoria. Finalmente, os índices de polidispersão (PDI), obtidos foram da ordem de 2,5 a 3,5.The emulsion polymerization of styrene in a microreactor Syrris 250 µL with static mixer junction \"T\" was studied in two steps. First, only the fluidynamics of this nonconventional device was evaluated, after the polymerization reaction was developed in order to observe how this factor influencing the system. The experiments were performed seeking to achieve higher conversions, keeping the stability of the emulsion. It was an exploratory work therefore is more like an evolutionary process. The ratio of two-phase flow rates was analyzed from which of them occurs droplet formation. The flow rate of dispersed phase (Qd) was kept constant and the continuous phase (Qc), was increased. It can be observed the decreasing of droplet diameter and a laminar flow regime. Later, it was carried out emulsion polymerization of styrene in the microreactor with restrictions for high flow rates. The process parameters were analyzed: the ratio Qc/Qd, the temperature and initiator concentration and then determine the effect that these variations cause the monomer conversion, the diameter, number of particles and the average molecular weight. The polymerization occurred to the sum of the flow rates Qc and Qd of around 100 µ L/min with 15% monomer in the formulation with the highest residence time of 2,5 minutes. For higher concentrations of monomer, above 15% was observed clogging in the microreactor channel. The monomer conversion rate raised with increasing temperature and with the concentration of initiator, but the largest value achieved was only 37% due to the low residence time. In this case, the molecular weights obtained were smaller as expected by theory. Finally, the polydispersity indexes obtained were around 2.5 to 3.5.
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Kashirsagar, Ravindra S. "Study of entry mechanism in emulsion polymerization." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/11747.
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Belleau, Francine. "Demulsification of an industrial emulsion using microorganisms." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66043.
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Cho, Wan-Goo. "Forces between liquid surfaces and emulsion stability." Thesis, University of Hull, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363201.
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Hollingsworth, K. G. "Characterisation of emulsion systems using NMR methods." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604170.
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Several aspects of emulsion characterisation via NMR are explored. This thesis begins by considering previous experimental work in determining the droplet-size distributions of emulsion systems by magnetic resonance restricted self-diffusion measurements. This is developed by applying regularisation techniques to analyse restricted diffusion measurements and avoid the limitation of fitting a particular functional form for the droplet-size distribution. Droplet-sizing is then extended to flowing emulsions by means of flow-compensated diffusion measurement. The success of this strategy is evaluated for several different model oil-in-water emulsions. An inverse Abel transform technique is applied to produce spatially-resolved droplet-size distributions for both stationary and flowing emulsion systems flowing within a pipe: a significant time saving is achieved by exploiting the symmetry of the system. The flow patterns of emulsions through an orifice plate, an elementary type of static mixer, are then considered. The ability of magnetic resonance to produce spatially-resolved velocity maps is exploited to make rheological measurement of emulsion systems. For the first time, the effect of altering the droplet-phase volume concentration on rheology is considered using magnetic resonance methods and the analysis is extended to emulsions having an apparent yield stress. The phenomenon of shear-induced migration of emulsions, unlike that of solid suspensions, has not previously been well studied: this work presents the first study of this effect by magnetic resonance methods. The effect of changing the volume concentration of droplets, the surfactant and the rotation speed of a Couette geometry are elucidated. One of the principal drawbacks of determining emulsion droplet-size distributions by magnetic resonance diffusion measurements is the time-consuming nature of the measurements: this work thus presents a fast method of making these measurements. This method is exploited to study both emulsion droplet coalescence and emulsion droplet breakup in a simple stirred vessel.
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van, Berkel Kim Yao-Hua. "Entry and the kinetics of emulsion polymerisation." Thesis, University of Canterbury. Chemistry, 2004. http://hdl.handle.net/10092/6111.
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An understanding of the process by which polymerising free radicals are created is of fundamental importance for any type of free radical polymerisation system. In the case of emulsion polymerisation this process is complicated by the fact that free radicals are usually generated in the aqueous phase, while the principal site of polymerisation is the interior of hydrophobic latex particles. This thesis details a study of the kinetics and mechanism for radical entry into latex particles in-emulsion polymerisation.
A systematic investigation is carried out identifying the influences of initiator, monomer and particle surface type on the entry efficiency. Experimental entry efficiencies are obtained from a range of seeded styrene emulsion polymerisation systems at 50°C, employing potassium peroxodisulfate and 2,2' -azobis-(2-methylpropionamidine) dihydrochloride as initiators, and using latex particles stabilised by positive or negative surface charge. Changing either initiator or particle type is seen to affect the entry efficiency. Experimental results are able to be rationalised in terms of an existing theory for entry which suggests that entry occurs for persulfate-derived radicals after addition to two styrene monomer units, and for amidinium-derived radicals after addition to only one styrene monomer unit.
Entry efficiencies are also obtained from seeded experiments at 50°C using persulfate as initiator and methyl methacrylate as monomer, with considerably greater uncertainty arising in this case due to unexplained variations in the "acceleration" during Interval II of polymerisation. Comparison with entry theory for this system indicates that entry occurs for a persulfate-derived radical only after addition to at least 20 methyl methacrylate monomer units. Attempts to confirm this inferred value by analysis of aqueous-phase oligomers using mass spectrometry and gel-permeation chromatography are inconclusive.
In the hope of improving the accuracy with which entry rate, data may be obtained from kinetic experiments the following investigations into more other aspects of emulsion polymerisation kinetics are carried out.
The contribution to entry from spontaneous polymerisation is measured for a wide range of styrene and methyl methacrylate systems and various mechanistic inferences are made. The particle surface and aqueous phase are identified as likely loci for spontaneous radical generation.
The nature of chain stopping reactions in emulsion polymerisations of methyl methacrylate at 50°C are investigated through kinetic experiments and analysis of polymer molecular weight distributions. The radical chain length distribution is found to be approximately ''transfercontrolled", and both kinetic data and molecular weight distributions are well described by current models for termination and the effects of column broadening in gel-permeation chromatography.
A new kinetic model for emulsion polymerisation is developed which extends the Smith-Ewart treatment to take account of all reactions of monomeric and aqueous-phase radicals. This new model treats exit and re-entry in terms of elementary physical and chemical processes, employing microscopic rate parameters and obviating the use of less meaningful parameters, such as k and a, which have traditionally been required for non-zero-one systems. The model is applied to the styrene and methyl methacrylate systems used in experimental work and confirms the accuracy of the entry data obtained using existing methods. However, no improvement in the fitting of methyl methacrylate acceleration data is obtained from using the new model with best estimates for all parameter values.
Finally, new approaches to modelling entry are proposed which may overcome the limitations posed by existing entry models. Most importantly, recommendations are made for including the kinetics of adsorption, desorption and entry of all aqueous radicals.
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Needham, D. "Developments in bitumen emulsion mixtures for roads." Thesis, University of Nottingham, 1996. http://eprints.nottingham.ac.uk/11101/.
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Bitumen emulsion mixtures, or cold mix, offers certain advantages over hot bituminous road mixtures in terms of potential cost savings, environmental factors, energy savings and easing of logistical difficulties inherent with hot mix. For these reasons, they are currently used in a number of regions including the United States of America, Continental Europe, Scandinavia, Southern Africa and Australia. However, cold mix has not been seriously evaluated or utilized in the UK until comparatively recently. This is due to the slow rate at which it builds strength or cures and its susceptibility to rainfall, particularly during this curing period. The overall aim of this research was, therefore, to study the behaviour of cold mix in terms of mechanical properties and the mechanisms involved in emulsion breaking and mixture curing to gain an insight into how performance may be improved. Mechanical properties were shown to be affected by a number of parameters, including binder grade, void content, curing time and additives such as cement. Fatigue tests showed that without cement, the performance in-situ of cold mix would be very poor. Pavement design calculations revealed that, with cement, emulsion mixtures could be expected to perform similarly to equivalent hot mix. Field trials have indicated that cold mix can be manufactured using conventional hot mix plant and laid using similar techniques. However, problems are still to be overcome in terms of the control of mixture composition and laying in adverse weather conditions. Fundamental tests have shown that emulsion droplet coalescence (which is an essential part of the curing process) was affected by pressure, bitumen type, emulsifier level, cement and temperature and that cement can cause emulsion charges to become more positive (or less negative) but other parameters had no effect on charge. It was also proved that cement can cause bitumen emulsion to set completely and that the residual binder has an increased viscosity compared with unmodified binder. This was shown to be due to the formation of a composite bitumen cement binder.
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Carey, Michelle. "Interaction of aromas with starch/emulsion systems." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268505.
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Prima-Hartley, Valerie Georgette Bernadette. "Lipoxygenase activity in model food emulsion systems." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267669.
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Chan, Chau Ping. "Stability and structure of suspo-emulsion components." Thesis, University of Bristol, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440050.
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Sachdev, Suchanuch. "Emulsion droplets as reactors for assembling nanoparticles." Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/36206.
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Materials on the nanoscale have very interesting properties. Hence, they are commonly used for a variety of applications such as drug delivery, bio-imaging and sensing devices. Moreover, coating these particles with other materials forming core@shell or Janus particles can further enhance their properties. However, for the particles to be used in medical and electronic devices, their properties such as size, shape and composition need to be precisely controlled. In this PhD., an emulsification technique was chosen to investigate the synthesis of nanoparticles; it is a simple process, does not require any harsh chemicals or temperature and is fast. Emulsification occurs when two or more immiscible liquids and surfactants are mixed. Here, emulsion droplets were produced using a microfluidic device which allowed for the creation of uniform droplets. These were employed as templates to synthesise and assemble nanomaterials. The main aim of the Ph.D. was to develop a droplet based synthesis process to generate nanoparticles and then assemble them into core@shell particles. This Ph.D., starts by synthesising Fe3O4 nanoparticles (~ 12 nm) and assembling them into microparticles (~ 1µm 2µm) using emulsion droplets as microreactors. By tuning the surfactant, droplet size and evaporation rate of the dispersed phase, microparticles of varying shapes and sizes, such as spherical or crumbled shapes, were produced. When these particles are compared with the commercially available particles, the magnetic content of the in-house particles, or sometimes referred to as Loughborough University Enterprises Ltd. (LUEL), are much higher and more uniform, hence resulting in faster separation when used for extraction of analytes. LUEL particles were supplied as part of commercial collaboration. The use of Pickering emulsions were then explored to create core@shell particles using gold nanoparticles instead of a surfactant to produce gold shells and the addition of pre-synthesised Fe3O4 nanoparticles results in Fe3O4@Au core@shell particles. This is the first time Pickering emulsions were used to produce Fe3O4@Au core@shell particles (~ 1.5 µm) within a microfluidic device. However, the shells were not uniform in thickness. In order to improve the coverage, nanoparticles were synthesised in situ at the droplet interface. By placing the gold chloride (AuCl4-) in the continuous phase and by varying the concentration of the electron donor in hexane droplet, single crystal gold nanoparticles and platelets were formed. The reaction is spontaneous at room temperature, creating gold nanoparticles at the interface of the emulsion droplet. The size and shape of the gold nanoparticles were controlled by varying the concentration of the reactants and the size of the droplets. By adding pre-synthesised particles (Fe3O4 nanoparticles) to the droplet, Au@Fe3O4 core@shell particles were formed with an approximate size of 250 nm. The same concept of forming core@shell particles using gold nanoparticles was further expanded by using other metal ions; palladium and silver. Unlike gold, palladium and silver only formed spherical nanoparticles, no platelets were observed. The addition of preformed iron oxide nanoparticles to the palladium results in core@shell particles. However, in the case of silver, no core@shell particles were formed. The study of the rate of reaction was conducted to understand the details of the mechanism. Overall, the process developed in this Ph.D. study allows for the facile synthesis of core@shell particles in a rapid, high throughput reaction. In the future, it is believed it could be scaled up for commercial purposes.