Mass transfer and interactions in microemulsions.
Item
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Title
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Mass transfer and interactions in microemulsions.
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Identifier
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AAI9119618
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identifier
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9119618
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Creator
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Chan, Yeung Yu.
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Contributor
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Adviser: Kevin McKeigue
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Date
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1991
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Chemical
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Abstract
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Interactions between the dispersed-phase droplets strongly influence the physical, thermodynamic, and transport properties of microemulsions. In water-in-oil microemulsions, these interactions have been incorrectly attributed to van der Waals forces acting between droplet's water cores. A novel mechanism is proposed for interdroplet interactions in water-in-oil microemulsions.;This theory is based on the premise that the random arrangement of the small number of ions within the water core of a microemulsion results in the droplet possessing a relatively large dipole moment. A series of Monte Carlo simulations were performed to determine the magnitude of this dipole moment and its polarizability for several water-in-oil microemulsion systems. The number of ions, the droplet size, and the surfactant's dissociation constant were varied in the simulations. A new theory for the interdroplet potential function is formulated which explicitly accounts for dipole--dipole and dipole--induced dipole attractions between droplets. A perturbation approach with a hard-sphere reference system is used to generate thermodynamic properties from the interdroplet potential function. The Hamaker constants and osmotic pressures predicted by this theory are found to be in good agreement with data in the literature. Specifically, the theory correctly predicts the decrease in attractions between droplets with increasing salt concentration.;An approach based on Smoluchowski's theory of colloid stability is used to generate an interdroplet mass transfer rate from the potential function. Finally, as an example to illustrate the utility of this approach, the particle size distribution of a microemulsion polymerization process is calculated. The results clearly suggest that the control of product size and product size distribution depends to a large degree on the ratio of interdroplet mass transfer rate to the rate of polymerization.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
