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

Abstract

The reported studies are related to a new group of intelligent materials, such as magnetorheological elastomers (MREs), which are composites of ferromagnetic particles embedded in elastomer matrix. Studies on fabrication of MREs were carried out using two different polyurethane elastomers as a matrix, ferromagnetic particles and coupling agent. The matrices were differed in elastomer stiffness and hardness. As a ferromagnetic component carbonyl-iron powder with particle size of 6-9 µm was used. Particles were oriented into chains under the external magnetic field of 240 kA/m. Samples with anisotropic particles arrangement and particles volume fraction equal to 11.5% were examined. Microstructure of MREs was observed using Scanning Electron Microscopy. Structural and magnetic anisotropy of the MREs was derived from the magnetic studies. Rheological properties of the MREs, such as storage and loss modulus and loss factor, were characterized as a function of shear frequency and strength of the magnetic field. Absolute and relative magnetorheological effects were calculated taking the microstructure into account, which was formed in the course of the MRE fabrication, by changing the elastomer type and application of the coupling agent. As a result of the studies it was found that the MREs with stiffer matrix exhibit much lower MR effect than the soft ones. Also the application of coupling agent lead to a decrease of MR effect by the formation of bound elastomer surrounding the particles, which increases the stiffness of the matrix.

The field-dependent complex modulus of magnetorheological elastomers consisting of sucrose acetate isobutyrate ester

“…This is because the stiffer matrix limits CIPs to displace when subjected to the magnetic field. This tendency agrees with previous report by Boczkowska and Awietjan (2011).…”

Microstructure and Properties of Magnetorheological Elastomers

“…As a result the absolute and relative MR effect is much higher in MREs obtained from the soft elastomer. MREs with the stiffer matrix (EPU 2.5) exhibit significant lower MR effect because the stiffer matrix makes impossible the particles to displace when they are subjected to the magnetic field [72].…”

Temperature effect on viscoelastic properties of anisotropic magnetorheological elastomers under compression

“…Magnetorheological elastomers (MREs) show the potential application in semi-active vibration control due to their dynamic properties that can be adjusted rapidly and reversibly by changing the external magnetic field [1][2][3][4]. It is well known that the dynamic mechanical properties of MREs are affected not only by its components and the fabrication process [5][6][7] but also by the in-service conditions such as load amplitude, excitation frequency, external magnetic field, and temperature etc. [8][9][10][11].…”