The objective of this thesis is to develop a new experimental method to characterize the diffusion of water in polymer resins, based on the evolution in the volume of water droplets as a function of time. A finite element model is established to model the mass transport of water droplet through evaporation and diffusion processes. Diffusivity of water into polymer resins is then extracted by matching the volume variation of the simulated water droplet to the experimental results. Capability of this method is demonstrated by determining the diffusivity of water into void-free epoxy and epoxy samples with voids. Diffusion coefficient value obtained from this method agrees with data from conventional water immersion method. The significantly small scale of the water droplet (less than 10 microliter) allows rapid characterization of diffusivity in hours instead of months as typically required by the conventional immersion method. The method developed here provides a useful tool for rapid and effective characterization of diffusivity of water in polymer substrates and can be extended to other substances as well. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

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Includes bibliographical references. Pt. 1. Clinical evaluation -- Pt. 2. A SEM and 'In-vitro' study.

Ion exchange equilibria are presented for [ ]??? ??? Au(CN)2 / Cl , [ ]??? ??? Au(CN)2 / SCN and SCN??? / Cl??? in aqueous solution, and in various mixed solvents, at 303K using Purolite A500 as the ion-exchanger. The mixed solvents investigated include water-acetone, water-dimethylsulfoxide (DMSO) and water-N-methyl-2-pyrrolidone (NMP). In aqueous solution, the selectivity of Purolite A500 for a given anion increases in the order: [ ]??? ??? &lt ??? &lt Cl SCN Au(CN)2 . This selectivity sequence confirms the high affinity of the ion exchange resin for the [ ]??? Au(CN)2 species. In mixed solvents, however, the selectivity of Purolite A500 for [ ]??? Au(CN)2 decreases with an increase in the composition of the organic solvent in the external solution. Mixed solvents containing greater than 60 mol% organic solvent are preferred for the displacement of [ ]??? Au(CN)2 from the resin. The effectiveness of a given type of mixed solvent generally increases in the following order: DMSO &it acetone &it NMP. The ion exchange equilibria are correlated using the Law of Mass Action, modified with activity coefficients, to determine the equilibrium constant for each binary system. The fitted values of the equilibrium constants are consistent with the trends observed in the ion exchange isotherms. The accuracy of the correlation results in the mixed solvent systems range from 1 to 10% and this is similar to the level of accuracy obtained for the ion exchange equilibria in aqueous solution. From these results it can be concluded that the Law of Mass Action is equally valid in mixed solvent systems. The variation in the equilibrium constant with mixed solvent composition, for a given binary system, correlates well with the dielectric constant of the mixed solvent. For a given value of the dielectric constant, however, the equilibrium constant, however, the equilibrium constant is dependent on the type of mixed solvent. A fundamental relationship is derived between the equilibrium constants and the Gibbs energies of transfer associated with the solvation of the ions in the mixed solvents. Based on this relationship, the redistribution of ions between the pore solution and the bulk mixed solvent, appears to be the most significant factor that governs the selectivity of the resin in mixed solvent systems.

Thesis (Ph.D)--Technische Universiteit Eindhoven, 2006. / Title from title screen (viewed on Dec. 6, 2007). Title from document title page. Includes bibliographical references. Available in PDF format via the World Wide Web.

Thesis (Ph.D)--University of Hong Kong, 1997. / A journal entitled Three-dimensional reconstruction of microleakage pattern using a sequential grinding technique by M.S. Gale, B.W. Darvell and G.S.P. Cheung bound at back of the thesis. Includes bibliographical references (leaves 495-520) Also available in print.

Thesis (M.D.S.)--University of Hong Kong, 1994. / Includes bibliographical references. Also available in print.

Thesis (Ph.D)--University of Hong Kong, 1997. / Includes bibliographical references (leaves 495-520) Also available in print.

Thesis (M.S.)--Ohio University, June, 2006. / Title from PDF t.p. Includes bibliographical references (p. 63-71)