TY - JOUR A1 - Kalita, Viktor M. A1 - Snarskii, Andrei A. A1 - Shamonin (Chamonine), Mikhail A1 - Zorinets, Denis T1 - Effect of single-particle magnetostriction on the shear modulus of compliant magnetoactive elastomers JF - Physical review E N2 - The influence of an external magnetic field on the static shear strain and the effective shear modulus of a magnetoactive elastomer (MAE) is studied theoretically in the framework of a recently introduced approach to the single-particle magnetostriction mechanism [V. M. Kalita et al., Phys. Rev. E 93, 062503 (2016)]. The planar problem of magnetostriction in an MAE with magnetically soft inclusions in the form of a thin disk (platelet) having the magnetic anisotropy in the plane of this disk is solved analytically. An external magnetic field acts with torques on magnetic filler particles, creates mechanical stresses in the vicinity of inclusions, induces shear strain, and increases the effective shear modulus of these composite materials. It is shown that the largest effect of the magnetic field on the effective shear modulus should be expected in MAEs with soft elastomer matrices, where the shear modulus of the matrix is less than the magnetic anisotropy constant of inclusions. It is derived that the effective shear modulus is nonlinearly dependent on the external magnetic field and approaches the saturation value in magnetic fields exceeding the field of particle anisotropy. It is shown that model calculations of the effective shear modulus correspond to a phenomenological definition of effective elastic moduli and magnetoelastic coupling constants. The obtained theoretical results compare well with known experimental data. Determination of effective elastic coefficients in MAEs and their dependence on magnetic field is discussed. The concentration dependence of the effective shear modulus at higher filler concentrations has been estimated using the method of Pade approximants, which predicts that both the absolute and relative changes of the magnetic-field-dependent effective shear modulus will significantly increase with the growing concentration of filler particles. KW - BEHAVIOR KW - composites KW - DEPENDENCE KW - FERROGELS KW - MECHANICAL-PROPERTIES KW - MICROSTRUCTURE KW - Polymer KW - PURE SHEAR KW - RHEOLOGY KW - SENSITIVE ELASTOMERS Y1 - 2017 U6 - https://doi.org/10.1103/PhysRevE.95.032503 VL - 95 IS - 3 PB - American Physical Society ER - TY - JOUR A1 - Bodnaruk, Andrii V. A1 - Kalita, Viktor M. A1 - Kulyk, Mykola M. A1 - Lozenko, Albert F. A1 - Ryabchenko, Sergey M. A1 - Snarskii, Andrei A. A1 - Brunhuber, Alexander A1 - Shamonin (Chamonine), Mikhail T1 - Temperature blocking and magnetization of magnetoactive elastomers JF - Journal of Magnetism and Magnetic Materials N2 - The magnetization of a magnetoactive elastomer (MAE) with microparticles of soft magnetic carbonyl iron embedded in a highly elastic matrix has been studied. It is shown that at high temperatures its magnetization curve has the form of a specific hysteresis loop. This hysteresis is attributed to the influence of displacement of magnetized particles in the elastically soft elastomer matrix under the effect of magnetic forces, leading to the change of magnetic interaction between the particles. In this case, there is a maximum in the field dependence of the magnetic susceptibility, the occurrence of which has been associated with the competition between rearrangement of particles, when they are displaced in a magnetic field, and saturation of particles' magnetization. When the MAE is cooled below approximately 225 K, both the magnetic hysteresis and the maximum in the field dependence of the magnetic susceptibility disappear. When the MAE material is cooled below the solidification temperature of the elastomer matrix, the displacements of the magnetic particles during magnetization are blocked by the rigid matrix. The magnetization reversal of the MAE is reversible. This means that the shape of subsequent magnetization loops remains constant and the sample returns into the initial non-magnetized state after the magnetic field is turned off. KW - Hysteresis loop KW - Magnetization reversal KW - magnetoactive elastomer KW - Magnetorheological elastomers KW - MICROSTRUCTURE KW - Solidification Y1 - 2019 U6 - https://doi.org/10.1016/j.jmmm.2018.10.005 VL - 471 IS - February SP - 464 EP - 467 PB - Elsevier ER - TY - JOUR A1 - Kalita, Viktor M. A1 - Snarskii, Andrei A. A1 - Zorinets, Denis A1 - Shamonin (Chamonine), Mikhail T1 - Single-particle mechanism of magnetostriction in magnetoactive elastomers JF - Physical Review E N2 - Magnetoactive elastomers (MAEs) are composite materials comprised of micrometer-sized ferromagnetic particles in a nonmagnetic elastomermatrix. Asingle-particle mechanism ofmagnetostriction in MAEs, assuming the rotation of a soft magnetic, mechanically rigid particle with uniaxial magnetic anisotropy in magnetic fields is identified and considered theoretically within the framework of an alternative model. In this mechanism, the total magnetic anisotropy energy of the filling particles in the matrix is the sum over single particles. Matrix displacements in the vicinity of the particle and the resulting direction of the magnetization vector are calculated. The effect of matrix deformation is pronounced well if the magnetic anisotropy coefficient K is much larger than the shear modulus mu of the elastic matrix. The feasibility of the proposed magnetostriction mechanism in soft magnetoactive elastomers and gels is elucidated. The magnetic-field-induced internal stresses in the matrix lead to effects of magnetodeformation and may increase the elastic moduli of these composite materials. KW - BEHAVIOR KW - Deformation KW - DEPENDENCE KW - FERROGELS KW - HOMOGENEOUS MAGNETIC-FIELD KW - magnetodeformation KW - MICROSTRUCTURE KW - SENSITIVE ELASTOMERS Y1 - 2016 U6 - https://doi.org/10.1103/PhysRevE.93.062503 VL - 93 IS - 6 PB - American Physical Society ER - TY - JOUR A1 - Belyaeva, Inna A. A1 - Kramarenko, Elena Yu A1 - Shamonin (Chamonine), Mikhail T1 - Magnetodielectric effect in magnetoactive elastomers: Transient response and hysteresis JF - POLYMER N2 - Magnetodielectric properties of magnetoactive elastomers comprising micrometer-sized iron particles dispersed in compliant elastomer matrices are experimentally studied in stepwise time-varying dc magnetic fields. It is found that imposition of magnetic field significantly increases both the effective lossless permittivity of these composite materials as well as their effective conductivity. These magnetodielectric effects are more pronounced for larger concentrations of soft-magnetic filler particles and softer elastomer matrices. The largest observed relative change of the effective dielectric constant in the maximum magnetic field of 0.57 T is of the order of 1000%. The largest observed absolute change of the loss tangent is approximately 0.8. The transient response of the magnetodielectric effect to a step magnetic-field excitation can be rather complex. It changes from a simple monotonic growth with time for small magnetic-field steps (<0.1 T) to a non-monotonic behavior with a significant rapidly appearing overshoot for large magnetic-field steps (>0.3 T). The settling time to the magnetic-field step excitation can reach roughly 1000 s and it depends on the applied magnetic field and sample composition. There is also significant hysteresis of the magnetodielectric effect on the externally applied magnetic field. These findings are attributed to the rearrangement of ferromagnetic filler particles in external magnetic fields. The results will be useful for understanding and predicting the transient behavior of magnetoactive elastomers in applications where the control magnetic field is time dependent. (C) 2017 Elsevier Ltd. All rights reserved. KW - BEHAVIOR KW - composites KW - DIELECTRIC-PROPERTIES KW - hysteresis KW - MAGNETIC-FIELD KW - magnetoactive elastomer KW - magnetodielectric effect KW - Magnetorhelogical elastomer KW - MELT STATE KW - MICROSTRUCTURE KW - POLYMER DEGRADATION KW - PROGRESS KW - Smart material KW - THERMOOXIDATIVE DEGRADATION KW - TIME-RESOLVED RHEOLOGY KW - Transient response Y1 - 2017 U6 - https://doi.org/10.1016/j.polymer.2017.08.056 VL - 127 SP - 119 EP - 128 PB - ELSEVIER ER - TY - JOUR A1 - Bodnaruk, Andrii V. A1 - Brunhuber, Alexander A1 - Kalita, Viktor M. A1 - Kulyk, Mykola M. A1 - Snarskii, Andrei A. A1 - Lozenko, Albert F. A1 - Ryabchenko, Sergey M. A1 - Shamonin (Chamonine), Mikhail T1 - Temperature-dependent magnetic properties of a magnetoactive elastomer: Immobilization of the soft-magnetic filler JF - Journal of Applied Physics N2 - The magnetic properties of a magnetoactive elastomer (MAE) filled with mu m-sized soft-magnetic iron particles have been experimentally studied in the temperature range between 150 K and 310 K. By changing the temperature, the elastic modulus of the elastomer matrix was modified, and it was possible to obtain magnetization curves for an invariable arrangement of particles in the sample and in the case when the particles were able to change their position within the MAE under the influence of magnetic forces. At low (less than 220 K) temperatures, when the matrix becomes rigid, the magnetization of the MAE does not show a hysteresis behavior, and it is characterized by a negative value of the Rayleigh constant. At room temperature, when the polymer matrix is compliant, a magnetic hysteresis exists where the dependence of the differential magnetic susceptibility on the magnetic field exhibits local maxima. The appearance of these maxima is explained by the elastic resistance of the matrix to the displacement of particles under the action of magnetic forces. KW - BEHAVIOR KW - composites KW - FIELD KW - GELS KW - hysteresis KW - Magnetorheological elastomers KW - MICROSTRUCTURE KW - PERMEABILITY KW - RAYLEIGH LAW KW - STRAIN Y1 - 2018 U6 - https://doi.org/10.1063/1.5023891 VL - 123 IS - 11 PB - AIP Publishing ER -