Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains xvii, 189 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 150-162).

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.Sc.(Chemistry))--University of Pretoria, 2008. / Includes bibliographical references (leaves 85-104).

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Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2012. / Emulsion explosives are classified as highly concentrated Water-in-Oil emulsions with an internal phase volume fraction of approximately 94%, i.e. far beyond the close packing limit of spherical droplets of 74%. These emulsions are thermodynamically unstable compounds and their instability is related to the crystallisation in the dispersed phase, which is a supersaturated solution of ammonium nitrate salt in water. This presents a problem, because the emulsion weakens or becomes unstable, which results in droplet crystallisation, so that the explosive generally loses at least some of its sensitivity to detonation. Considerable effort has been applied to the improvement of emulsion stability by explosive manufacturers, but important aspects such as the effect of salt and surfactant content/type in emulsions are not fully understood and described in the literature. The purpose of this study was to investigate these shortcomings and to focus on the effect of surfactant nature and concentration and electrolyte concentration/type on the interfacial properties and interactions in emulsion explosives. Interfacial properties (interfacial tension and interfacial elasticity), thermal behaviour (freezing temperatures) of emulsions and rheological aspects (viscoelastic and flow properties) were investigated in terms of surfactant-electrolyte interactions.

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No description available.

The kinetics of the reduction of silver amine complexes in aqueous solutions were investigated and found to be second order overall, the rate being proportional to silver complex and hydrogen concentrations. These systems were studied under conditions of essentially complete complexing and therefore the rates were independent of amine concentration. The rates were also shown to be independent of amine perchlorate concentration and thus of pH within a limited range. Enthalpies and entropies of activation were determined for each system and an attempt was made to correlate kinetic data with information on complex stability constants and amine basicities. The most prominent trend in the results was the inverse dependence of rate on complex stability constant. Two mechanisms are proposed both involving heterolytic cleavage of the hydrogen molecule. In the first mechanism, the proton released in the rate determining step is taken up by the basic ligand directly. In the second mechanism, a water molecule replaces the amine ligand and acts as the proton acceptor. The strength of the silver-ligand bond and the difficulty of ligand replacement by water account for the inverse dependence of rate on complex stability for each mechanism respectively. Arguments are presented to support both mechanisms. In general dibasic amine complexes activated hydrogen more readily and displayed a more negative entropy of activation than do the monoamine complexes. These observations are attributed to the presence of a free basic group in the ligand aiding the cleavage of the hydrogen molecule in the rate determining step. The proximity of the second basic group to the central silver atom also appears to be important. These effects and the possible role of the free basic group in the ligand are discussed. / Science, Faculty of / Chemistry, Department of / Graduate

Merocyanine dyes exhibit interesting changes in absorption spectra with changes in solvent polarity. For example solutions of 1-methyl-4- (oxocyclohexadienylidene) ethylidene -1,4-dihydropyridine (MOED) are yellow, red, violet, or blue, in water, ethanol, acetone or pyridine respectively.1 More striking effects are observed when aqueous solutions are diluted with various proportions of the organic co-solvents such as pyridine. The color varies across the whole spectrum from golden yellow to blue.These characteristic properties of merocyanine dyes in various organic solvents have been extensively studied and correlations between [see PDF file for formula]max and solvent polarity have been determined. In this work the visible absorption have been determined. In this work the visible absorption properties of merocyanine dyes were studied in cationic and anionic surfactants in order to investigate the behaviour of these dyes in micellar system and to use their electronic spectra as probes of the micellar environment. Since the description of the literature and discussion of the experimental results will involve certain terms and concepts from surfactant chemistry, it is necessary to introduce the subject.