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Models for structure-rheology of highly concentrated emulsions
Author(s)
Foudazi, Reza
Date Issued
2009
Type
Thesis
Publisher
Cape Peninsula University of Technology
Abstract
Highly concentrated emulsions (HCE) are classified as high internal phase ratio
emulsions (or simply HIPRE), and the dispersed phase droplets are ranged In a
hexagonal closely packed configuration. This closely packed configuration and the
profound hydrodynamic interaction between neighbouring droplets induce mechanical
interference between the droplets, thus prohibiting their free movement. Hence, while
the highly concentrated emulsions consist of very low viscosity and inelastic
components, they show gel-like behaviour with high elasticity and non-Newtonian flow
response. It has been suggested in the literature that this behaviour originated from
interfacial energy in terms of Laplace pressure. Therefore, the scaling of rheological
properties with Laplace pressure is expected, but several publications show a deviation
from this scaling behaviour. It seems that the source of deviation from this scaling is
interdroplet interaction, which can contribute to the rheological behaviour of highly
concentrated emulsions. The shear modulus of highly concentrated emulsions in the
presence of interdroplet interaction was developed in this work. The prediction of model
was verified by the data presented in the literature. It was shown that a small source of
interdroplet interaction can result in deviation from scaling of shear modulus with
Laplace pressure.
emulsions (or simply HIPRE), and the dispersed phase droplets are ranged In a
hexagonal closely packed configuration. This closely packed configuration and the
profound hydrodynamic interaction between neighbouring droplets induce mechanical
interference between the droplets, thus prohibiting their free movement. Hence, while
the highly concentrated emulsions consist of very low viscosity and inelastic
components, they show gel-like behaviour with high elasticity and non-Newtonian flow
response. It has been suggested in the literature that this behaviour originated from
interfacial energy in terms of Laplace pressure. Therefore, the scaling of rheological
properties with Laplace pressure is expected, but several publications show a deviation
from this scaling behaviour. It seems that the source of deviation from this scaling is
interdroplet interaction, which can contribute to the rheological behaviour of highly
concentrated emulsions. The shear modulus of highly concentrated emulsions in the
presence of interdroplet interaction was developed in this work. The prediction of model
was verified by the data presented in the literature. It was shown that a small source of
interdroplet interaction can result in deviation from scaling of shear modulus with
Laplace pressure.
Additional information
Thesis (DTech (Chemical Engineering))--Cape Peninsula University of Technology, 2009.
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207241880_Foudazi_Reza_Dtech_Chemical Engineering_Eng_2009_20109958.pdf
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