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The effect of the surfactant hydrophilic groups and concentration of electrolyte in an internal aqueous phase on the interfacial interactions and rheology of highly concentrated emulsions
Author(s)
Kovalchuk, Karina
Date Issued
2012
Type
Thesis
Publisher
Cape Peninsula University of Technology
Abstract
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.
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.
Additional information
Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2012.
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208231013_Kovalchuk_K_Mtech_Chemical Engineering_Eng_2012_20122127.pdf
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Thesis
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