Viscometric studies in the process of synthesis of magnetic lubricant nano-oils
A.N. Bolotov, O.O. Novikova, V.V. Meshkov
Tver State Technical University
DOI: 10.26456/pcascnn/2022.14.531
Original article
Abstract: In the field of tribology, magnetic lubricating oils are promising, in which polymers are used to increase their colloidal stability, but their use is limited by the low magnetization of the colloid. It is possible to increase the magnetization of nanooils by synthesizing polymer shells directly on the surface of magnetic particles in the process of obtaining nanooils. The features of the technology for the synthesis of magnetic lubricating nanooils with polymeric solvation shells on particles, which protect them from coagulation, are described. Polymerization of hydroxy acid molecules proceeds by the mechanism of polycondensation on the solid surface of magnetite. The viscosity of the magnetic colloid increases due to the increase in the thickness of the solvate shell. Proceeding from this, a differential equation is proposed, which shows the dependence of the growth rate of the colloid viscosity on the rate of the polycondensation reaction. An experimental verification of the equation showed that it is fulfilled with an accuracy up to 8%. The resulting equation makes it possible to determine an important thermodynamic characteristic – the activation energy of the process of synthesis of polymer shells on the surface of dispersed particles. For calculations, it is necessary to
know the rate of change in the viscosity of a colloid with a dispersion medium without a monomer (hydroacid). Therefore, in the process of the polymer synthesis, samples of the intermediate magnetic colloid of a small volume are taken, which are used to determine the viscosity of the colloid and dispersion medium containing monomers. Then the viscosity of the colloid with a pure dispersion medium is found, which is necessary for calculating the activation energy of the polycondensation reaction. According to estimates, the error in determining the activation energy does not exceed 11%. In practice, using the values of the activation energy of polymerization, it is possible to carry out a purposeful choice of the optimal temperature-time regime for stabilizing the magnetic colloid in order to obtain a magnetic nanooil with the required viscosity and aggregative stability characteristics. Experimental studies were carried out on specially designed instruments for assessing the colloidal stability and dynamic viscosity of magnetic colloids.
Keywords: colloidal systems, magnetic lubricating nanooils, viscosity, colloidal stability, activation energy of polymerization
- Alexander N. Bolotov – Dr. Sc., Professor, Head of the Applied Physics Department, Tver State Technical University
- Olga O. Novikova – Ph. D., Full Docent, Applied Physics Department, Tver State Technical University
- Vladimir V. Meshkov – Dr. Sc., Full Professor, Technology and Mechanical Engineering Department, Tver State Technical University
Reference:
Bolotov, A.N. Viscometric studies in the process of synthesis of magnetic lubricant nano-oils / A.N. Bolotov, O.O. Novikova, V.V. Meshkov // Physical and chemical aspects of the study of clusters, nanostructures and nanomaterials. — 2022. — I. 14. — P. 531-544. DOI: 10.26456/pcascnn/2022.14.531. (In Russian).
Full article (in Russian): download PDF file
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