Studies on silicone anisotropic magnetoactive composites (original) (raw)
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Anisotropic magnetoactive composites features of the properties
International Scientific and Practical Symposium "Materials Science and Technology" (MST2021)
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-and nanostructured surfaces. The use of nuclear gamma resonance made it possible to identify the iron filler electronic configuration in these anisotropic composites.
Effects of Filler Distribution on Magnetorheological Silicon-Based Composites
Materials
The smart materials subclass of magnetorheological elastomer (MRE) composites is presented in this work, which aimed to investigate the influence of filler distribution on surface morphology. Iron particles with sizes ranging from 20 to 150 µm were incorporated into the elastomer matrix and a 30% volume fraction (V%) was chosen as the optimal quantity for the filler amount in the elastomer composite. The surface morphology of MRE composites was examined by 3D micro-computed tomography (µCT) and scanning electron microscopy (SEM) techniques. Isotropic and anisotropic distributions of the iron particles were estimated in the magnetorheological elastomer composites. The filler particle distribution at various heights of the MRE composites was examined. The isotropic distribution of filler particles was observed without any influence from the magnetic field during sample preparation. The anisotropic arrangement of iron fillers within the MRE composites was observed in the presence of a ...
Dynamic force microscopy of anisotropic magnetically active composites
PROCEEDINGS OF THE III INTERNATIONAL CONFERENCE ON ADVANCED TECHNOLOGIES IN MATERIALS SCIENCE, MECHANICAL AND AUTOMATION ENGINEERING: MIP: Engineering-III – 2021, 2021
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 by small external magnetic fields was found. Mössbauer spectroscopy use allowed determining the iron filler electronic configuration parameters in these composites. The obtained results were discussed and the conclusions about these materials prospects for practical applications were drawn.
Magnetoactive elastomer composites
Polymer Testing, 2004
This paper deals with the development of magnetoactive elastomers and the exploration of some of their potential applications. In the course of material development, samples of particle-filled silicone rubber were produced and their mechanical and magnetic properties were experimentally determined. The test specimens consisted of pure and filled silicone with randomly dispersed as well as aligned magnetizable particle chains. To align the embedded particles in the elastomer, cross-linking of the resin took place in a magnetic field. Composite elastomer samples with different types of micron-size particles and various volume fractions were tested. Through alignment of the embedded particles, relative to pure silicone, the tensile strength increased by 80%, the tensile modulus by 200%, and the compression modulus by more than 300%. The maximum tensile strain of filled samples was generally reduced; however, samples with longitudinally aligned particles retained a relatively high strain capability as in the pure silicone rubber. Furthermore, to determine the active response of the composite, magnetic tests and coupled mechanical-magnetic experiments were performed. The magnetoactive elastomer composites produced and tested in this work demonstrated certain actuator force properties. The equivalent magnetic force calculated on the basis of these experiments and the magnetosolid mechanics theory showed the dependence of the magnetic force on the distribution of the particles in the elastomer. The elasto-magnetic behavior of beam samples was investigated by exposing the filled elastomer to the action of a permanent magnet at various gap distances, which led to the determination of a so-called magnetic bending stiffness. Moreover, through these experiments the influence of the particle alignment on the critical gap distance of the elastomagnetic instability of composite elastomer was quantitatively estimated. The compression tests on cylindrical samples in the absence and the presence of a magnetic field showed that the magnetic field would increase the stiffness of the material. These experiments lead to useful hints regarding the use of such elastomer composites as tunable force structural elements.
Magnetic anisotropy in magnetoactive elastomers, enabled by matrix elasticity
Polymer, 2019
Polydimethylsiloxane based magnetoactive elastomers demonstrate above the melting transition range (e.g. at room temperature) an induced uniaxial magnetic anisotropy, which grows with increasing magnetic field. By freezing a material down to 150 K, displaced iron microparticles are immobilized, so that the magnetic anisotropy can be measured. Magnetic anisotropy "constant" is a consequence of particle displacements and a characteristic of the energy of internal deformations in the polymer matrix. The maximum anisotropy constant of the filling is at least one order of magnitude larger than the shear modulus of the pure elastomer (matrix). In a magnetic field, the gain in the rigidity of the composite material is attributed to the magnetomechanical coupling, which is in turn a source of anisotropy. The concept of effective magnetic field felt by the magnetization allows one to explain the magnetization curve at room temperature from low-temperature measurements. The results can be useful for developing vibration absorbers and isolators.
Solid State Phenomena, 2012
Results on anisotropic magnetorheological elastomers' magnetoelasticity are presented and discussed. In the dipole approximation, and considering the MRE as a continuous linear body, the effects of magnetic field on its main elastic properties (linear deformations and Young module) are investigated. Experimental evidences that the compression of the cylindrical bar is influenced by the intensity of the longitudinal magnetic field and the Young module of the MRE sample increases with the intensity H of the longitudinal magnetic field are obtained and the results discussed.
Journal of Industrial and Engineering Chemistry, 2012
This paper deals with the process of achievement of anisotropic magnetorheological elastomers (MREs), based on silicone rubber and iron nanoparticles. Plane capacitors are manufactured with MREs. The capacity C of the plane capacitors is measured as function of the intensity H of the magnetic field. By using the approximation of the dipolar magnetic moment and the ideal elastic body model, respectively, the tensions and deformations field and respectively the elasticity module of MREs function of H have been determined, for magnetic field values of up to 1000 kA/m. The obtained results are presented and discussed.
This paper focuses on novel iron-based soft magnetic composites synthesis utilizing high thermal stability silicone resin to coat iron powder. The effect of an annealing treatment on the magnetic properties of synthesized magnets was investigated. The coated silicone insulating layer was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. Silicone uniformly coated the powder surface, resulting in a reduction of the imaginary part of the permeability, thereby increasing the electrical resistivity and the operating frequency of the synthesized magnets. The annealing treatment increased the initial permeability, the maximum permeability, and the magnetic induction, and decreased the coercivity. Annealing at 580 1C increased the maximum permeability by 72.5%. The result of annealing at 580 1C shows that the ferromagnetic resonance frequency increased from 2 kHz for conventional epoxy resin coated samples to 80 kHz for the silicone resin insulated composites.
Magnetic Hybrid-Materials, 2021
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 the composite is a reflection of interactions occurring between the polymer matrix and the particles also participating in interactions among themselves. For example, introduction of magnetically hard components into the formula results in the origination of a number of significantly different behavioral features entirely unknown to magnetorheological composites of the classic type. Optical observation of samples based on magnetically hard filler gave the opportunity to establish that initial magnetization imparts magnetic moments to initially unmagnetized grains, as a result of which chain-like structures continue to be a feature of the material even after external field removal. In addition, applying a reverse field causes them to turn into the polymer as they rearrange into new ring-like structures. Exploration of the relationship between the rheological properties and magnetic field conducted on a rheometer using vibrational mechanical analysis showed an increase of the relative elastic modulus by more than two orders of magnitude or by 3.8 MPa, whereas the loss factor exhibited steady growth with the field up to a value of 0.7 being significantly higher than that demonstrated by elastomers with no magnetically hard particles. At the same time, measuring the electroconductivity of elastomers filled with a nickel-electroplated carbonyl iron powder made it possible to observe that such composites demonstrated an increase of variation of the resistivity of the composite influenced by magnetic field in comparison to elastomers containing untreated iron particles. The studies conducted indicate that this material exhibits both magnetorheological and
On anisotropic mechanical properties of heterogeneous magnetic polymeric composites
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2019
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. Non-magnetized and pre-magnetized specimens are characterized using a planar shear and axial loading in an externally applied homogeneous magnetic field. The field direction differs relative to the direction of the field used for the specimens pre-magnetization. Results of the different methods allow comparison of the tensile shear moduli for the samples with an initially identical composition. Obtained results demonstrate a strong correlation between the composite behaviour and orientation of the magnetic field used for the pre-magnetization of the sample relative to the external field applied to a sample during the test. Composites pre...