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Shklyaev S.,RAS Institute of Continuous Media Mechanics
EPL | Year: 2015

Self-propulsion of a Janus droplet in a solution of surfactant, which reacts on a half of a drop surface, is studied theoretically. The droplet acts as a catalytic motor creating a concentration gradient, which generates its surface-tension-driven motion; the self-propulsion speed is rather high, and more. This catalytic motor has several advantages over other micromotors: simple manufacturing, easily attained neutral buoyancy. In contrast to a single-fluid droplet, which demonstrates a self-propulsion as a result of symmetry breaking instability, for the Janus one no stability threshold exists; hence, the droplet radius can be scaled down to micrometers. © CopyrightEPLA, 2015.

Morozov I.A.,RAS Institute of Continuous Media Mechanics
Polymer Composites | Year: 2013

Segmentation algorithms have been developed to study the surface of filled rubbers using atomic force microscopy (AFM) images. The analysis reveals two types of segments in the material: micropellets (large, dense inclusions of a insufficiently ground filler) and aggregates (small primary filler inclusions). The proposed approach allows us to find the minimum size of a representative area, starting from the filler distribution can be treated as homogeneous (mesoscale). Secondary structures (clusters) created by aggregates are identified and their fractal parameters are calculated. The validity of the approach for the analysis of rubbers filled with carbon black is demonstrated. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers Copyright © 2013 Society of Plastics Engineers.

Lebedev A.V.,RAS Institute of Continuous Media Mechanics
Colloid Journal | Year: 2010

It is established that the working temperature range of a magnetic fluid (MF) stabilized with a mixture of oleic and linoleic acids is widened to -100°C and, when the linoleic acid mass fraction in the mixed surfactant is 10%, the fluid becomes unpolymerizable. The stability of the MF with respect to a coagulant (isopropanol) is studied. The dependence of the magnetic susceptibility of the stable fraction of the fluid on the volume fraction of the alcohol almost coincides with the data obtained for an MF stabilized with oleic acid. The MF is separated into coarse and finely dispersed fractions. The temperature dependence of the magnetic susceptibility is investigated for the coarse fraction at low temperatures. The magnetic susceptibility is shown to drastically decrease below -80°C because of the mechanical blocking of particles. © 2010 Pleiades Publishing, Ltd.

Morozov I.A.,RAS Institute of Continuous Media Mechanics
KGK Kautschuk Gummi Kunststoffe | Year: 2011

A new method for quantitative analysis of the structure of filled rubbers by atomic force microscopy (AFM) has been developed. A distinctive feature of this approach is the splitting of the detected surface microrelief, at a first stage, into separate structures, designated as clusters. The height level, where the splitting is done, is controlled by the total number of clusters per 1 μm2 (this value must be maximum), their compactness (its minimum value is attributed to branched structures) and their volume fraction (which is approximately equal to the given filler volume fraction). Further stages of investigations include a statistical characterization of the structure and distribution of the clusters. Furthermore, calculations of the Morishita index (a measure of cluster distribution), area, size, perimeter, degree of orientation and fractal characteristics of the examined structures are presented. The validity of the method has been verified by studying EPDM-rubbers filled with N330 carbon black, Silica Aerosil 200 and Aerosil R974 of filler fractions 20 and 40 phr, and by investigating a stretched natural rubber samples filled with N339 carbon black (50 phr).

Lebedev A.V.,RAS Institute of Continuous Media Mechanics
Colloid Journal | Year: 2014

The temperature dependence of the saturation magnetization of a magnetite-based magnetic fluid has been directly measured with a vibrating-coil magnetometer equipped with a superconducting solenoid. The magnetization varies in accordance with the 1 - αT 2 law. Coefficient α = 1.4 × 10-6 is almost twice as high as that of monolithic magnetite. The results of measuring the susceptibility of magnetic fluids stabilized with oleic and linoleic acids have been analyzed using novel corrections to the temperature dependence of particle magnetization. The susceptibility of ultimately concentrated samples is in good agreement with the Ivanov-Huke-Lücke and Morozov theories. The susceptibility of samples with a medium concentration is adequately described by the Ivanov theory alone. The susceptibility of low-concentrated samples increases to the level predicted by the Morozov theory in the case of particle aggregation. The widening of the particle size distribution leads to a reduction in the level of the interparticle interactions. © 2014 Pleiades Publishing, Ltd.

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