Intelligent magnetorheological elastomer composites
Polimery 2013, No 6, 443
The study is related to a new group of intelligent materials, namely magnetorheological elastomer composites (MRE), composed of ferromagnetic particles dispersed in an elastomeric matrix. They exhibit reversible changes of their properties and shape under the magnetic field, what makes them attractive for applications as dampers, sensors or actuators. The microstructure of the produced MRE was studied using scanning electron microscopy. In order to determine the magnetic and structural anisotropy of MRE, their magnetic properties were investigated. The rheological properties of MRE were also characterized in a broad range. The relative magnetorheological effect was evaluated by analyzing the influence of the volume fraction, size and arrangement of the particles on the microstructure of selected composite. It was found, that MRE with an anisotropic microstructure formed during the preparation under the magnetic field show much higher magnetorheological effect than MRE with an isotropic arrangement of the particles, added in the same amount to the elastomeric matrix. A non-linear change of the rheological properties versus particle fraction was also observed, as a result of the structural and magnetic anisotropy, which has a major influence on the change in MRE properties under the magnetic field. Moreover, it was found that the magnetorheological effect can be controlled by changes in the particle alignment according to the magnetic field direction. It means that to obtain a sufficiently high magnetorheological effect it is not necessary to introduce a large amount of magnetic particles into the polymer matrix, but it can be achieved by formation of an appropriate particle microstructure. This is beneficial for reducing the weight of devices based on MRE.