Enhancement of radio-absorbing properties and thermal conductivity of polysiloxane-based magnetorheological elastomers by the alignment of filler particles

Abstract

A design for the fabrication of more effective, thin, light-weight radio-absorbers (RAs) based on magnetorheological elastomers (MREs) is demonstrated. Carbonyl iron (CI) particles were incorporated into polydimethylsiloxane matrix either homogeneously (isotropic) or with preferential orientation into chain-like structures (anisotropic). The reflection coefficient (R) of MRE-based single-layer metal-backed RAs was calculated on the basis of transmission line theory. The results show that the orientation of CI particles strongly enhances the permittivity of the systems, while preserving their permeability, which ultimately manifests itself in enhanced absorption of electromagnetic (EM) energy and reduced thickness of RAs. Thus, RAs based on anisotropic MREs are characterized by superior EM shielding capability in the microwave frequency range compared to their isotropic analogues, which offers great practical as well as economic advantages. Moreover, the thermal conductivity of both types of RAs was investigated, since efficient energy dissipation is important to prevent heat build-up under a radio-absorbing shield and thus to extend the service life of the protected device.

Tailoring Performance, Damping, and Surface Properties of Magnetorheological Elastomers via Particle-Grafting Technology

“…The bulk properties of the MREs were the subject of numerous studies [1,4,10,13,18,20,21,26,29,40,44,51,52,53,54] however, the research of their surface properties is still limited. Yet, the MREs were recently shown to be exceptional materials with tunable surface roughness [55], which opens new avenues in the context of possible applications.…”

“…High stability and tunable viscoelastic moduli changes make the MREs suitable materials for the applications such as vibration absorbers, adaptive dampers, or stiffness tunable mounts [7,8,9,10]. Undoubtedly, pioneer applications such as artificial muscles [11], micro-fluid transport systems [12], radio-absorbers [13], sensors [14], or active elements of electric circuits [15] based on the MREs concept have been reported.…”

Magnetorheological Elastomers: Fabrication, Characteristics, and Applications

“…Regarding the orientation effect of CI particles, it was further reported that the orientation of CI particles strongly enhances the permittivity of the systems, while preserving their permeability, which ultimately manifests itself in enhanced absorption of electromagnetic energy and reduced thickness of radio-absorbers. Thus, radio-absorbers based on anisotropic MREs are characterized by superior EM shielding capability in the microwave frequency range compared to their isotropic analogues [ 152 ].…”

Functional Magnetic Composites Based on Hexaferrites: Correlation of the Composition, Magnetic and High-Frequency Properties

“…One of the major tasks in creating modern mobile communication devices is the development of new materials which can work in a wide (up to 100 GHz) frequency range in switches, circulators, phase shifters, transceivers, antennas and effective electromagnetic radiation (EMR) absorbers, which improve the electromagnetic compatibilities of devices [1][2][3][4][5]. M-type hexagonal ferrites are one of the most prospective electromagnetic materials for application in the centimeter and millimeter wave range due to the large values of permeability and magnetization, and good dielectric properties at microwave frequencies [6][7][8][9][10].…”