Enhancement in Magnetorheological Effect of Magnetorheological Elastomers by Surface Modification of Iron Particles

Abstract

In order to obtain magnetorheological (MR) elastomers with high magnetorheological effect, a family of anisotropic rubber-based MR elastomers was developed using a new form of chemical modification. Three different kinds of surfactants, i.e. anionic, nonionic and compound surfactants, were employed separately to modify iron particles. The MR effect was evaluated by measuring the dynamic shear modulus of MR elastomer with a magneto-combined dynamic mechanical analyzer. Results show that the relative MR effect can be up to 188% when the iron particles are modified with 15% Span 80. Besides the surface activity of Span 80, however, such high modifying effect is partly due to the plasticizing effect of Span 80. Compared with the single surfactant, the superior surface activity of compound surfactant makes the relative MR effect reach 77% at a low content of 0.4%. Scanning electron microscope observation shows that the modification of compound surfactant results in perfect compatibility between particles and rubber matrix and special self-assembled structure of particles. Such special structure has been proved beneficial to the improvement of the relative MR effect.

Recent Progress on Magnetorheological Solids: Materials, Fabrication, Testing, and Applications

“…[125,129,132] The irregular shape iron particles are usually found in sizes of above 50 mm. [162] The bonding between the iron particles and the composite matrix plays an important role in MRE performance. Although, those special shapes are not available on the market, the synthesis of iron particles with a controlled shape can be initially fabricated as performed by researchers in ref.…”

“…[108,[118][119][120]162] Surface treatment is well known through polymerization or coating. [108,[118][119][120]162] Surface treatment is well known through polymerization or coating.…”

“…Surface modification of the iron particles, which is initially applied in the MR fluids, gives better performance compared to conventional MR fluids in terms of stability against sedimentation. [162] The use of silane coupling agent methyltrimethoxysilane by Kashima et al [121] was intended to change the surface of the carbonyl iron from hydrophilic to hydrophobic. [108,118] The application of surface polymerization on MREs iron particles was initiated by Wang et al [43] by means of silane coupling agents KH-550 and AH-151.…”

Effect of the elastomer stiffness and coupling agents on rheological properties of magnetorheological elastomers

“…Gong et al [13] and Lokander and Stenberg [9] reported the advantageously influence on the MR effect of the addition of plasticizers to the silicon rubber due to the decrease of the polymer matrix stiffness. Jiang et al [14] indicate on the positive effect of the particles surface modification on the increase of the MR effect, while Zhang et al [15], Fan et al [16] and Li et al [17] show that the enhancement of the particle-polymer matrix interaction leads to the decrease of MR effect due to the existence of bound-rubber phenomenon. The improvement of filler-matrix interaction is an effective way to improve the mechanical properties of materials; however in the case of MREs it can affect the MR effect.…”

Mechanical Properties of Magneto‐Sensitive Elastomers in a Homogeneous Magnetic Field: Theory and Experiment

“…Another important topic is the influence of the magnetic field on the mechanical moduli of MSEs. Many experimental works studied the dependence of the static mechanical moduli of MSE on the magnitude of external magnetic field . The experimental works show that the static shear moduli of MSEs increase with increasing strength of the magnetic field and depend on the microstructure of these materials, e.g., on the volume fraction and spatial distribution of magnetic particles …”