Release:
2019, Vol. 5. №1About the authors:
Lyudmila P. Semikhina, Dr. Sci. (Phys.-Math.), Professor, Institute of Physics and Technology, University of Tyumen; semihina@mail.ruAbstract:
This article showcases an oil sample and the demulsifier used for its dehydration, as well as 50 and 98 percentile forms of two non-ionic surfactants using the Brookfield DV-II+Pro rotational viscometer, analyzing the viscosities µ of oil’s and micelle’s disperse systems depending on temperature T at various shear stresses τ.
The authors have revealed the similarity of all investigated disperse systems, expressed in their dependences of lnµ on (1/T) with reliability not lower than 0.99 breaking into two linear sections with a sharp bend at the temperature T*≈35-45 °C, which corresponds to the temperature of the phase transition. Thus, the difference in the internal structure of particles of the oil and micelle dispersion systems does not lead to a fundamental difference in their rheological properties, which does not exceed the difference between micelle systems.
The most important consequence of the identified similarity of the oil and micelle dispersion systems is the detection of a very close value of the phase transition temperature T*=(40±5) °C, at which all the studied systems experience a jump in the activation energy of a viscous flow and a sharp change in the particle size of their dispersed phase. On the case of micelle dispersion systems, the authors have established that this phase transition is practically independent of the melting temperature of the components contained in them, and it is also observed in the absence of reagents in them with a melting point of the order of T*=35-45°C.
Therefore, the results did not confirm the hypothesis that the phase transition in the oil dispersion systems at T*=(40±5) °C is due to the melting of paraffin. The authors suppose that in the oil and micelle dispersion systems at T*, there is a phase transition from the dispersed phase particles from quasi-crystalline to micelle state, that is, temperature T* is the temperature on the Kraft line. Possible models of this phase transition and their good agreement with experimental data obtained in the work are considered.
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