The Magnetoviscoelastic Response of Elastomer Composites Consisting of Ferrous Particles Embedded in a Polymer Matrix

Abstract

The mechanical response of elastomer composites to applied magnetic fields is examined. These elastomer composites consist of carbonyl iron particles embedded within a molded elastomer matrix. The composite is subjected to a strong magnetic field during curing, which causes the iron particles to form columnar structures that are parallel to the applied field. This special composite geometry is known to enhance the mechanical response to the application of post-cured magnetic fields. Experimental data is presented that shows that up to a 0.6 MPa change in mechanical shear modulus (which represents 30-40% change in modulus for the materials tested) is possible in response to an applied magnetic field for a composite containing 30% (V/V) iron particles. A simple quasi-static dipole model is presented to examine the magnetoviscoelastic effect of these elastomer composites. The model is semi-empirical in that it may be fit to experimental data over a broad range of applied fields by adjusting a parameter that accounts for unmodeled multipolar magnetic interactions between particles within the composite. Such elastomer composites hold promise in enabling variable stiffness devices and adaptive structures.

Magnetorheological Elastomers and Their Applications

“…For example, Shiga et al [2] prepared a kind of composite gel with magnetic properties. Then, Jolly et al [3] tested and analysis the mechanical properties of silicon rubber based magnetorheological elastomer. When the magnetic field was 0.8T, the shear modulus ratio increased about 40% of the initial value.…”

“…into chain-like columnar structures). To produce an aligned particle structure, the magnetic field is applied to the polymer composite during crosslinking so that the columnar structures can form and become locked in place upon the final cure [2][3][4][5][6][7][8][9][10].…”

Experimental Investigation of an Adaptively Tuned Dynamic Absorber Incorporating Magnetorheological Elastomer with Self-Sensing Property

“…While all these investigations mainly focused on the evaluation of the viscoelastic property along the shear direction, the material property of MRE in tensile, compression, and squeeze modes, were also studied [9,10]. Others have suggested the theoretical models explaining the mechanism of the MR effect and numerically predicted the mechanical response of MREs [11][12][13][14][15].…”

Preparation and properties of magnetorheological elastomers based on silicon rubber/polystyrene blend matrix

“…9 However, the typical magnetic fields needed to align the magnetic particles are very strong and about 8 Â 10 6 A/m, which makes the manufacture complicated and difficult to be broadly applied. 4 Recently, Lokander and Stenberg 10,11 have studied the isotropic MR rubber. They have made MR elastomers by embedding large irregular particles into the nitrile rubber without using the magnetic fields to align the particles, and these MR elastomers have a large absolute MR effect.…”

“…The magnetic particles commonly have been aligned by an applied magnetic field prior to the curing of the matrix. And they have been fabricated based on different matrix, i.e., silicone elastomers, [3][4][5] poly(vinyl alcohol), 6 gelatin, 7 hard natural or synthesized rubber, 8 and polyurethane sealant. 9 However, the typical magnetic fields needed to align the magnetic particles are very strong and about 8 Â 10 6 A/m, which makes the manufacture complicated and difficult to be broadly applied.…”