Hemijska industrija 2013 Volume 67, Issue 2, Pages: 293-301
https://doi.org/10.2298/HEMIND120216070S
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Rheology of unstable mineral emulsions
Sokolović Dunja S. (Faculty of Technology, Novi Sad)
Šećerov-Sokolović Radmila M. (Faculty of Technology, Novi Sad)
Sokolović Slobodan M. (Faculty of Technical Sciences, Novi Sad)
In this paper, the rheology of mineral oils and their unstable water emulsion
were investigated. The oil samples were domestic crude oil UA, its fractions
UA1, UA4 and blend semi-product UP1, while the concentration of oil in water
emulsions was in the range from 1 up to 30%. The results were analyzed based
on shear stress. The oil samples UA, UA1 and UP1 are Newtonian fluids, while
UA4 is pseudoplastic fluid. The samples UA and UA4 show higher value of shear
stress (83.75 Pa, 297 Pa), then other two samples UA1 and UP1 (18.41 Pa,
17.52 Pa). Rheology of investigated oils due to its complex chemical
composition should be analyzed as a simultaneous effect of all their
components. Therefore, structural composition of the oils was determined,
namely content of paraffins, naphthenes, aromatics and asphaltenes. All
samples contain paraffins, naphthenes and aromatics but only oils UA and UA4
contain asphaltenes as well. All investigated emulsions except 30% EUA4 are
Newtonian fluids. The EUA4 30% emulsion shows pseudoplastic behaviour, and it
is the only 30% emulsion among investigated ones that achieves lower shear
stress then its oil. The characteristics of oil samples that could have an
influence on their properties and their emulsion rheology, were determined.
These characteristics are: neutralization number, interfacial tension,
dielectric constant, and emulsivity. Oil samples UA and UA4 have
significantly higher values of neutralization number, dielectric constants,
and emulsivity. The sample UA has the lowest value of interface tension and
the greatest emulsivity, indicating that this oil, among all investigated,
has the highest preference for building emulsion. This could be the reason
why 20% and 30% emulsions of the oil UA achieve the highest shear stress
among all investigated emulsions.
Keywords: oil rheology, emulsion rheology, unstable emulsions