Heterogeneous nucleation of bubbles on an advancing solidification front during freezing of water containing a dissolved gas has been experimentally and analytically studied. The formation of bubbles resulting from supersaturation of liquids is commonly encountered in different fields such as heat transfer, manufacturing, and bioscience. In this work, sizes of nucleating bubbles and concentration profiles of dissolved oxygen and carbon dioxide gases in water ahead of the solidification front have been measured. From successful comparisons between the measured and predicted critical radii of nucleating bubbles and distributions of dissolved gas content, phenomena of heterogeneous nucleation in a binary weak solution during the freezing process are quantitatively confirmed. The results show that an increase in gas content at the solidification front in the liquid decreases the free energy barrier and critical radii of bubbles that are formed on the solidification front. In the early stage of solidification, sizes of the critical radii decrease and the number of nucleating bubbles increase. As solidification rates decrease later, content of the dissolved gas in the liquid on the advancing interface decreases and the critical radii of nucleating bubbles increase.

The overall crystallization kinetics of isotactic polystyrene (i-PS), polyethylene terephthalate (PET), and their nucleant-filled composites were examined using differential scanning calorimetry (D.S.C.). The study also included a photomicroscopic analysis of the number of nuclei formed per unit area and the spherulitic growth rate for i-PS and nucleated i-PS. / The isothermal crystallization of PET and i-PS showed that in some systems the addition of nucleant caused a slowing down of the crystallization process. This is the first reported observation of the retardation of rate in the presence of particular nucleant. The results are interpreted on the basis that the nucleant is inhibiting the growth of the crystals and thus slowing the overall rate of crystallization. Microscopic measurements of i-PS spherulites showed that the addition of silica reduced the radial growth rate. The data are analyzed by current theory and an extension to that theory is proposed which relates the polymer-nucleant interaction energy to the spherulitic growth rate of a nucleated system.

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Thesis (Ph. D.)--University of Texas at El Paso, 2007. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (Ph. D.)--University of Adelaide, Dept. of Chemical Engineering, 1990. / Includes bibliographical references (leaves 228-237).

Dissertation (Ph.D.)--University of Toledo, 2008. / Typescript. "As partial fulfillment of the requirements for the Doctor of Philosophy Degree in Physics." Bibliography: leaves 130-137.