Temperature-Dependent Magnetic Properties of Magnetorheological Elastomers

Abstract

We report on an investigation of the temperature-dependent magnetic properties of magnetorheological elastomers (MREs). These are a class of composites that consist of magnetically permeable particles dispersed in a nonmagnetic polymeric matrix. Under the application of an external magnetic field, a large deformation occurs altering the mechanical properties of these materials. Due to their magnetoelastic coupling response, these materials are finding an increasing interest among the scientific community. These polymer-based composites' performance depends on many factors, which temperature is one of the biggest influencing factors requiring further investigation. In this work, the magnetic properties of isotropic and anisotropic polyurethane-based MRE with different iron (Fe) particle loading fractions (50, 60, 70, and 80% by weight) were investigated under different temperatures. From the analysis, the magnetization curves of these materials are observed to overlap for the different measured temperature values. The variation of various magnetic properties including saturation magnetization and differential susceptibility with temperature was also determined. The results show ~ 2.5% decrement in the saturation magnetization for each of the loading fractions, between the lowest (300K) and the highest (400K) measured temperature. On the other hand, the initial differential susceptibility exhibits different trends with increasing temperature. Generally, the magnetization response of these materials is seen to be only slightly sensitive to temperature changes. Additionally, the magnetization response is observed to be highly dependent on particle loading fractions and particle orientation within the elastomer.

Inductive and magnetorheological properties of soft and hard magnetic fillers in elastomers

“…Even the induced electrical energy is higher for the isotropic samples which can be explained by the contribution of the internal magnetization behaviour of the samples. Anisotropic CIP compounds have a faster saturation in dependence of an applied field, because of higher initial local fields and therefore faster saturation, which is consistent with an initially higher slope of the magnetization [25]. Isotropic samples have a lower initial slope and therefore saturation is not reached as fast.…”

Magnetic susceptibility and response time of isotropic and structured magnetorheological elastomers

“…The magnitude of the difference in case of the bM MRE samples is 0.095 (+39.4%) and 0.005 (−2.2%). According to Kiarie et al (2022) this tendency is only observable for the initial susceptibility (in the linear region of the magnetization curve, when H e → 0 ). Above a threshold field strength the trend is reversed, and the susceptibility of the MRE along P oriented structures is smaller, while for the O type it is larger compared to the isotropic case.…”

“…The magnitude of the difference in case of the bM MRE samples is 0.095 (+ 39.4%) and 0.005 (22.2%). According to Kiarie et al (2022) this tendency is only observable for the initial susceptibility (in the linear region of the magnetization curve, when H e ! 0).…”