A study of surfactant equations of state and transport dynamics at the air-water interface.
Item
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Title
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A study of surfactant equations of state and transport dynamics at the air-water interface.
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Identifier
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AAI9618090
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identifier
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9618090
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Creator
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Pan, Rennan.
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Contributor
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Adviser: Charles Maldarelli
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Date
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1996
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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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This dissertation studies the adsorption isotherm, surface equation of state and transport dynamics of water soluble nonionic surfactants at the air/water interface. A method which involves using the pendant bubble as a monolayer film balance is developed to directly measure the surface tension as a function of surface concentration. By using this method, both the equilibrium and dynamic surface tension/surface concentration data are measured, which effectively prove the commonly used assumption that the equilibrium and dynamic surface equations of state are equivalent. A molecular interaction model is developed for nonionic surfactants based on a molecular interaction approach, which includes: a kinetic rate equation, an adsorption isotherm and a surface equation of state. This model describes the equilibrium surface tensions and surface tension/surface concentration data better than the existing models. The four model parameters for a few polyethoxylated surfactants are obtained. The surfactant transport dynamics onto the air/water interface is studied for a model surfactant {dollar}\rm C\sb{12}E\sb6{dollar}. Two new ideas to promote the kinetic effects in the transport dynamics have been proposed. One is for clean interface adsorption, which states that the kinetic effect is increasing when the bulk concentration increases. The other is for overcrowded interface desorption, which says that the kinetic effect is increasing when the initial surface concentration increases. These ideas are proved theoretically and experimentally. By using these ideas, the kinetic rate constants and diffusion coefficient are measured for the model surfactant {dollar}\rm C\sb{12}E\sb6{dollar}.
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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.
