Gennady V Stepanov

• GNIIChTEOS

Novel magnetoactive thin film composites based on silicone elastomer with nano-structured iron fillers have been synthesized. Atomic force microscopy studies have established these composites surface topography unique sensitivity to restructuring induced by the atomic force microscope probe. Application low external magnetic field also resulted in...

The mechanical response of a cantilever made of a magnetoactive elastomer (MAE) that is positioned on a solid plane surface and is subjected to a uniform magnetic field is studied. The MAE is of the magnetically soft type, i.e., its filler particles become magnetized only in the presence of external field. Test observations with the applied field n...

Magnetoactive (aka magnetorheological) elastomer is a composite material consisting of an elastic matrix and magnetic filling substance. A study dedicated to the relationship between its viscoelastic parameters and the strength of the external magnetic field has been done. Under the influence of a field, the material can demonstrate elasticity and...

The compositions and structures of methyl MQ resins with different M/Q ratios were studied using NMR and IR spectroscopy, as well as gel permeation chromatography (GPC). It was found that the M/Q ratio affects the molecular weight of the siloxanes under consideration and the activity of hetero- and homopolycondensation. Depending on the M/Q ratio,...

Magnetoactive (aka magnetorheological) elastomer composites, which are elastic polymer matrices filled with micron-sized particles of a ferromagnet, are a novel type of magnetically controllable material. In addition to their complex magnetomechanical behavior, magnetoactive elastomers, as conducting substances, possess electrical resistivity that...

Magnetoresistivity and piezoresistivity of magnetoactive elastomers G.V. Stepanov⁎, A.V. Bakhtiiarov, D.A. Lobanov, P.A. Storozhenko State Research Institute for Chemical Technologies of Organoelement Compounds, Moscow 111123, Russia A R T I C L E I N F O Keywords: Magnetoactive elastomers Magnetorheological elastomers Electrical resistivity Piezor...

The magnetoelastic material samples in compression tests are investigated. The studied materials rheological properties are carried out on an automated testing machine. Compressive moduli changes diagrams depending on deformation values up to limiting extreme values are plotted. Transition ranges from linear to nonlinear, longitudinal compression m...

New anisotropic magnetically active elastomers using carbonyl iron micrometer size ferromagnetic fillers in the silicone matrix were synthesized. Samples with orientation of the outer magnetic field strength vector applied in perpendicular or in parallel direction to the mold surface during polymerizing composite mass were investigated. These compo...

Smart materials such as magnetoactive elastomers (MAEs) combine elastic and magnetic properties that can be significantly changed in response to a magnetic field and therefore offer enormous potential for applications in both scientific research and engineering. When such an elastomer contains microsized hard magnetic particles, it can become an el...

New anisotropic silicone magnetoactive composites were synthesized and studied. The surface structure and filler microdimensions in these elastomers were determined by electron microscopy. The atomic force microscopy use made it possible to determine significant surface deformations and magnetostrictive effects when small external magnetic fields a...

Nanoplatforms applied for the loading of anticancer drugs is a cutting-edge approach for drug delivery to tumors and reduction of toxic effects on healthy cells. In this study, we describe the synthesis and compare the sorption properties of four types of potential doxorubicin-carriers, in which iron oxide nanoparticles (IONs) are functionalized wi...

This paper deals with the polymer composite material unique properties on self-restoration after ultimate compressive loads application. Material is based on polydimethylsiloxane elastomeric matrix with carbonyl iron particles isotropic fillers in concentration 75% wt. This composite mechanical characteristic ranges were studied in comparison with...

New anisotropic silicone magnetically active elastomers were synthesized and studied. Significant surface deformations and magnetostrictive effects in the obtained composites under the application of small external magnetic fields were visualized by the atomic force microscopy methods. This opens up the controlled wrinkling possibility for micro- a...

In this work, a highly efficient and environmentally friendly method for extracting palladium from hydrochloric acid media was developed. The method uses a magnetic sorbent carrying an organophosphorus extractant, which is not washed from the sorbent into the aqueous phase. The extractant was characterized by ¹H, ¹³C, and ³¹P NMR spectroscopy and M...

Creation of and the following research on systems featuring elastomer filled with a magnetic disperse material with good electroconductive properties have been a continuation of the development of magnetorheological fluids with the goal of finding compositions exhibiting a stronger magnetorheological effect. More profound investigations have reveal...

We present results of experimental and theoretical study of the effect of external magnetic field on elastic properties of dense soft magnetic polymers filled with micron-sized magnetizable particles. The samples were cured without a magnetic field, thus with isotropic internal morphology of the particles disposition. Experiments demonstrate that u...

Dynamic tests of new magnetoactive elastomers were carried out in various amplitude-frequency modes on vibrodynamic stands. These materials regular changes in resonance properties under the external constant magnetic fields and loads influence have been established. The relationship between vibrodynamic and damping properties in these composites an...

New anisotropic silicone magnetically active elastomers were synthesized and investigated by microscopy and spectroscopy. The record magnetostriction value in the obtained composites was determined by dynamic force microscopy, and their surface original wrinkled microstructure was visualized. The anisotropic elastomers surface topography changing b...

Aimed at creating a magnetic filling material with improved electroconducting properties for novel magneto-controllable composites, a method is developed of electroplating metals onto particles of carbonyl iron powders of various shape and size. The experimentally observed improvement in the effective conductivity of thus produced nickel-coatings c...

Hybrid magnetic elastomers (HMEs) belong to a novel type of magnetocontrollable elastic materials capable of demonstrating extensive variations of their parameters under the influence ofmagnetic fields. Like all cognate materials, HMEs are based on deformable polymer filled with a mixed or modified powder. The complex of properties possessed by the...

The paper gives an overview of tunable elastic magnetic composites based on silicon rubber matrix highly filled with a magnetic soft and hard filler. The magnetic soft phase, which is represented by iron microparticles, allows active control of the physical properties of the composites, while the magnetically hard phase (e.g. neodymium-iron-boron a...

Experimental studies magnetorheological elastomer specimens dynamic properties under the magnetic fields action on the vibrostend are carried out. Amplitude-frequency characteristics have been obtained. The magnetic field effect on the silicone magnetoreactive elastomers deformation properties and damping coefficients experimentally is established.

Dielectric properties of two series of magnetoactive elastomers (MAEs) based on a soft silicone matrix containing 35 vol% of magnetic particles were studied experimentally in a wide temperature range. In the first series, a hybrid filler representing a mixture of magnetically hard NdFeB particles of irregular shape and an average size of 50 μm and...

The dynamic properties of magnetically active elastomers based on silicone polymer matrix with various ferromagnetic fillers under the external magnetic fields influence using a vibration-testing complex have been studied. The amplitude-frequency characteristics and the investigated composites resonance frequencies changes under such influences are...

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На виброиспытательном комплексе изучены динамические свойства магнитоактивных эластомеров на основе силиконовой полимерной матрицы с различными ферромагнитными наполнителями в условиях воздействия внешних магнитных полей. По результатам полученных при виброиспытаниях опытных данных построены амплитудно-частотные характеристики и установлены законом...

In this study, we report on the experimentally observed phenomenon of ring-like structures formation from chains of magnetic microparticles in magnetoactive elastomers based on magnetic hard powder. In order to find an explanation for the specific macroscopic magnetic properties of composites, microstructural observations on the elastic composite b...

Hybrid magnetic elastomers (HMEs) belong to a novel type of magnetocontrollable elastic materials capable of demonstrating extensive variations of their parameters under the influence of magnetic fields. Like all cognate materials, HMEs are based on deformable polymer filled with a mixed or modified powder. The complex of properties possessed by th...

The paper gives an overview of tunable elastic magnetic composites based on silicon rubber matrix highly filled with a magnetic soft and hard filler. The magnetic soft phase, which is represented by iron microparticles, allows active control of the physical properties of the composites, while the magnetically hard phase (e.g. neodymium–iron–boron a...

New elastomeric silicone composites with ferromagnetic fillers have been synthesized. The deformation and strength properties of these magnetoactive elastomers in compression with additional imposition of an external magnetic field have been studied. The influence of a filler microparticles restructuring in external magnetic fields, established ear...

The paper describes experimental research into the dynamic properties of magnetoactive elastic polymers. Tests on a vibrostendshow that in certain ranges the test material is able to change the frequency of resonance vibrations under the influence of magnetic fields. Experimental data obtained during testing a sample of magnetorheological elastomer...

Within the frames of this study, the synthesis of a permalloy to be used as a filler for magnetoactive and magnetorheological elastomers (MAEs and MREs) was carried out. By means of the mechanochemical method, an alloy with the composition 75 wt.% of Fe and 25 wt.% of Ni was obtained. The powder of the product was utilized in the synthesis of MAEs....

We present a theoretical approach for calculating the state of stress induced by a uniform magnetic field in confined magnetoactive elastomers of arbitrary shape. The theory explicitly includes the magnetic field generated by magnetizable spherical inclusions in the sample interior assuming a non-linear magnetization behavior. The initial spatial d...

Elongations of magnetoactive elastomers (MAEs) under ascending–descending uniform magnetic fields were studied experimentally using a laboratory apparatus specifically designed to measure large extensional strains (up to 20%) in compliant MAEs. In the literature, such a phenomenon is usually denoted as giant magnetostriction. The synthesized cylind...

Elastomeric silicone composites with ferromagnetic filler are investigated. The distribution of carbonyl iron filler in the polymer matrix by scanning electron microscopy is visualized. Using atomic force microscopy the magnetostrictive characteristics of these materials are established. ⁵⁷ Fe nuclei hyperfine parameters of the iron filler atoms in...

The main objectives of this highlight are to give an overview of major achievements in the field of soft magnetoactive elastomers based on silicone rubbers over the past twenty years and to demonstrate the prospects for their further development.

Oscillograms of changes in the accelerations of amplitudes, phases and oscillation frequencies under the action of specified loads at the input and output of the test sample of magnetorheological elastomer are recorded and analyzed. At the input, the sample is loaded with a smoothly increasing harmonic force arising from the imbalance of the unbala...

New silicone magnetoactive elastomers have been synthesized and studied. Significant magnetostrictive effects in the synthesized composites were visualized by microscopy. The obtained results can be the basis for the design of controlled dampers and promising magnetostrictive engines of a new generation with micro and nanoscale positioning accuracy...

Проведены синтез наночастиц магнетита кубической формы, и сравнительный анализ эффекта вы- деления тепла с наночастицами игольчатой и сферической формы в низкочастотном магнитном по- ле. Определены размер, форма и магнитные свойства исследованных образцов. Исследовано влия- ние концентрации, температурной обработки частиц, частоты и величины переме...

Experimental studies of the magnetorheological elastomer dynamic properties under the influence of vibrations and magnetic fields have been carried out. Amplitude-frequency characteristics of these composites were studied. The computational modeling was made and a device for creation and control of magnetoactive composite movements was developed. T...

This research is dedicated to the specifics of the behavior exhibited by elastomer filled with magnetically hard (high-coercivity) particles influenced by magnetic fields. Composite materials of this type are also mentioned as magnetorheological, magnetoactive, and hybrid. There have been done studies on the magnetization processes taking place in...

The magnetic properties of hybrid magnetic elastomers (HME) featuring a type of magnetorheological elastomer filled with high-coercivity (a.k.a. magnetically hard) particles have been studied. Introduction of magnetically hard components into the formula significantly modifies both magnetic and rheological parameters of the composite. An additional...

The shape and size distribution of micro- and nanoscale particles of a magnetoactive filler in an elastomeric matrix on the surface of a magnetorheological composite are determined by SEM and AFM methods. With the aid of AFM, the phenomena of the restructuring of particles of filler aggregates on the surface of elastomers under the action of a weak...

Magneto-active elastomers (MAEs) based on a silicon polymer matrix filled with magnetic carbonyl iron microparticles have been synthesized. Both isotropic samples and samples micro-structured by an external magnetic field have been obtained. The radio-absorbing properties of the MAEs have experimentally been studied in the frequency range 2–10 GHz...

Electron and atomic force microscopy were used for the study of magnetoactive filler surface microstructure in a magnetorheological composite. The particles redistribution phenomena of filler aggregates on the surface of elastomers under the action of a small external applied constant magnetic field are visualized. A model is proposed for the inter...

The hyperthermic effect of spherical and needle-shaped iron oxide nanoparticles coated with oleic and citric acids in a low-frequency alternating magnetic field is studied. Measurements of their magnetic properties reveal the superparamagnetic properties of nanomagnetite and the presence of the hysteresis loop in maghemite. The heat release of disp...

The forces of interaction between samples of magnetoactive elastomers (MAE) and hard magnetic composite seals based on neodymium–iron–boron (NdFeB) particles are investigated. The force of interaction between an MAE tape and a seal with 90% NdFeB particles is comparable to the one between an MAE tape and a seal based on cooriented permanent magnets...

The magnetodielectric response of magnetoactive elastomers (MAEs) in its dependence on filler concentration, magnetic field, and test frequency is studied experimentally. MAEs are synthesized on the basis of a silicone matrix filled with spherical carbonyl iron particles characterized by a mean diameter of 4.5 µm. The concentration of the magnetic...

This study is devoted to the magneto-mechanical characterization of heterogeneous magnetoactive elastomers based on an elastic polydimethylsiloxane matrix with embedded spherical magnetic soft microparticles and magnetic hard microparticles of irregular shape. An issue of the anisotropic mechanical properties of these smart composites is considered...

This study focusses on a magnetoactive elastomeric composite based on a polydimethylsiloxane matrix highly filled with a mixed magnetic powder. The powder contains a mixture of carbonyl iron and magnetically hard NdFeB alloy spherical microparticles. Magnetoactive elastomer samples with different ratios of the magnetically hard and soft filler were...

Magnetoactive elastomers (MAEs) on the basis of a silicone matrix filled with carbonyl iron microparticles are developed for an envisaged application in eye surgery for treatment of complicated retinal detachments. The proposed magnetic fixator of an eye retina consists of an MAE seal placed inside an eye in the area of a retinal break, and an exte...

Silicone oil tamponade is widely used in the surgical treatment of retinal detachments. The article provides analysis of mechanical forces exerted to the retina in various parts of the vitreous cavity. There are areas of tamponade effect insufficiency, in which it may be beneficial to create additional means which would support the retina keeping i...

A dynamic model of the starting current of an active damper based on a magnetorheological elastomer is described, Experimental data for the damper are derived.

The design of a controlled damper on the basis of a magnetorheological elastomer is described. The technique of determining the dynamic characteristics of the damper, such as the stability, the time constant, and the positioning error, in an active step-by-step displacement mode is presented. A dynamic model of the automatic-control system of the c...

Critical issues of the oscillating shear rheometry with disc-shaped elastomer specimens are exemplified. A torsional oscillation method to characterise magnetorheological elastomers (MREs) using a rheometer is introduced and compared to the standard procedure with disc-shaped specimens. Advantages and disadvantages of the method are identified. It...

Several fractional rheological models containing one or two fractional elements in addition to the classical springs and dashpots have been proposed to describe the dynamic behavior of magnetoactive elastomers (MAEs) in magnetic fields. To test the models, MAEs containing 70, 75 and 80 wt% of carbonyl iron particles with the diameter of 3–5 μm have...

In this work, a new method for increasing optical anisotropy of a ferrocolloid through introducing the coiled polymer molecules or elongated nanosized non-magnetic particles is realized. Since the dimensions of structural elements comprising such a binary colloidal solution are small compared to the wavelength, the ferrocolloid remains optically ho...

In this study we experimentally examine the mechanical stress induced by the striction of hybrid magnetoactive elastic composites in the direction parallel to an externally applied magnetic field. Elastic samples based on a polydimethylsiloxane matrix with embedded spherical magnetic soft carbonyl iron particles, spherical magnetic hard NdFeB-alloy...

A series of magnetoactive elastomer (MAE) coatings consisting of a silicone matrix and carbonyl iron particles (3-5[U+202F]μm in diameter) have been synthesized and their hydrophobic properties have been investigated in various magnetic fields of disk-shaped permanent NdFeB magnets. Concentration of magnetic filler in MAEs has been varied in the ra...

The present paper introduces an operating principle and concept of an acceleration sensor with an adaptable measuring range and sensitivity basing on the adjustability of the material properties of magneto-sensitive elastomers. The development of such a sensor requires a comprehensive understanding of the behaviour of the utilized material. Therefo...

Smart materials like magnetic hybrid elastomers (MHEs) are based on an elastic composite with a complex hybrid filler of magnetically hard and soft particles. Due to their unique magnetic field depending characteristics, these elastomers offer great potential for designing sensor systems with a complex adaptive behaviour and operating sensitivity....

We explore the possibility of creating an effective retinal fixator on the basis of magnetoactive elastomers (MAEs) and systems of permanent magnets. MAEs consist of silicone elastomer matrix with embedded magnetic iron microparticles. We study theoretically and experimentally magnetic forces acting between MAE samples and permanent magnets in vari...

Magnetoactive elastomers are promising for use in designing of magnetically operated devices for signal processing and sensors. The results from studying the electrophysical and acoustic properties of new magnetoactive elastomers structured by a nonuniform magnetic field are presented. It is shown that the prestructuring of the magnetic disperse fi...

Hybrid magnetic elastomers belonging to the family of magnetorheological elastomers contain magnetically hard components and are of the utmost interest for the development of semiactive and active damping devices as well as actuators and sensors. The processes of magnetizing of such elastomers are accompanied by structural rearrangements inside the...

Magnetoactive elastomers (MAE) based on soft silicone matrices, filled with various proportions of large diameter (approximately 50 μm) iron and small diameter (approximately 0.5 μm) magnetite particles are synthesized. Their rheological behavior in homogeneous magnetic fields up to 600 mT is studied in detail. The addition of small magnetite parti...

We propose a theoretical model of magnetostriction hysteresis in soft magnetic gels filled by micronsized magnetizable particles. The hysteresis is explained by unification of the particles into linear chain-like aggregates while the field increasing and rupture of the chains when the field is decreased.

The development of sensor systems with a complex adaptive regulation of the operating sensitivity and behaviour is an actual scientific and technical challenge. Smart materials like magneto-sensitive elastomers (MSE) are seen as one potential solution for this problem, since their mechanical properties may be controlled by external magnetic fields....

We propose the results of research on the magnetic properties of magnetoactive elastomers containing particles of a hard magnetic filler. According to our understanding, the mechanism of re-magnetizing of the composite is based on two competing processes, being the re-magnetizing of the magnetic filler and mechanical rotation of particles inside of...

We present results of an experimental and theoretical study of the magnetic properties of soft magnetic gels consisting of micron-sized magnetizable particles embedded in a polymer matrix. Experiments demonstrate hysteretic dependences of composite magnetization on an applied magnetic field and non-monotonic, with maximum, dependence of the sample...

A fractional calculus approach is applied to model constitutive behavior of magnetorheological elastomers. To test the model results magnetorheological elastomers containing different concentrations of iron particles have been synthesized and their rheological behavior in various magnetic fields has been studied experimentally. The fractional model...

Transient rheological response of magnetoactive elastomers is experimentally studied using dynamic torsion at a fixed oscillation frequency in temporally stepwise changing magnetic fields and oscillation amplitudes. For step magnetic-field excitations, at least three exponential functions are required to reasonably describe the time behavior of the...

Hysteresis in dynamic modulus, loss factor and normal forces of magnetoactive elastomers (MAEs) comprising various proportions of small (3–5 μm) and large (50–60 μm) ferromagnetic particles are experimentally studied using dynamic torsion performed at a fixed oscillation frequency in varying DC magnetic fields. It is shown that hysteresis is a char...

In this study we introduce an elastic composite, which has been manufactured using a fine carbonyl iron powder coated with a polymeric dielectric shell and dispersed in a silicone elastomer in a way as it is typically done manufacturing magnetorheological elastomers. Due to the used filler such a material possesses the capability of exhibiting magn...

Magnetic elastomers (MEs) based on a silicone matrix and magnetically hard NdFeB particles have been synthesized and their magnetic and viscoelastic properties have been studied depending on the size and concentration of magnetic particles and the magnetizing field. It has been shown that magnetic particles can rotate in soft polymer matrix under a...

The dynamic modulus and the loss factor of magnetorheological elastomers (MRE) of various compositions and anisotropies are studied by dynamic torsion oscillations performed in the absence and in the presence of an external magnetic field. The emphasis is on Payne effect, i.e. dependence of the elastomers magnetorheological characteristics on the s...

This work is focused on the magnetic response of magnetoactive elastomer (MAE) based on silicone polymer matrices filled with magnetic particles of magnetically hard NdFeB-alloy. Viscoelastic properties of MAE were studied by the method of oscillation shear. After magnetization in an external magnetic field of 2 T MAE samples demonstrate more than...

A measuring system is proposed for studying the dynamic damping of new magnetically active elastomers. Tests show that the viscoelastic and damping properties of magnetically active elastomers may vary under the action of the magnetic field and the load.

Magnetorheological elastomers (MRE) have been synthesized on the basis of a silicon compound and a mixture of carbonyl iron particles of sizes 3–5 and 40–80 μm. Their viscoelastic properties have been studied by dynamic shear oscillations of various amplitudes on a stress controlled rheometer. The magnetic response of the obtained materials has bee...

The model of a magnetoactive elastomer (MAE) based on a system of single-domain fine particles distributed in an elastically deformable matrix is considered. The dependence of a deformation of samples with different concentrations of an ultra-dispersed magnetic material with a given value of a uniformly applied external magnetic field has been calc...

The effect of a uniform magnetic field on the permittivity of magnetorheological elastomers (MREs) is studied. MREs were synthesized on the basis of silicone rubber and magnetic fillers of various chemical nature (Fe, NdFeB and Fe3O4) and particle sizes. The value of permittivity was obtained from the measurements of the capacity of a plane capacit...

The paper contains experimental results for the velocity of longitudinal acoustic wave, density, longitudinal elasticity modulus and viscosity coefficient of nanocomposite Fe-gel material with different percent content of iron nanoparticles. The concise description of the preparation technology of the samples under study is also included. The deter...

A study of the influence of magnetic field on the resistivity of the magnetoactive (magnetorheological) elastomer has been conducted. The material consisted of a soft polymer matrix and magnetic fillers being powders of Fe, Ni, and the Fe–Nd–B alloy. Under the influence of the field with a value of 300 mT, the elastomer exhibited the magnetoresisti...

Rheological properties of magnetoactive elastomers with complex composition are studied. Samples of the elastomer consisting of a soft silicon matrix with embedded micron-sized particles of FeNdB and carbonyl iron powder have been magnetized in the uniform magnetic field of varying strength in order to provide different remanence magnetizations. Th...