# Magneto-Rheological Elastomer Composites. A Review
## 4 Future Prospectus on the Applications of MREs Composite  
MRE composites have opportunities in the field of elastomer devices in practical way of engineering applications. MRE composites under tension, compression, and shear test shows possible uses in the application areas of vibration isolation and absorption capacities. Combined approach of shear and compression test may allow application in the area of sensing of elastomer devices. MR elastomer devices include large adaptive working frequency range, low power consumption, and compact configuration. Thus, given a sufficient magnetic field is provided, devices with large changes in their modulus and damping (i.e., MR effect), between field-on and field-off status, can offer a great adaptive range. Effect of filler size, shape, and nature of the matrix has a significant role in the quality of MREs composite. The volume fraction of 30% of filler particles are considered to be optimized for significant distribution of fillers within the matrix. The circular and smaller particles such as carbonyl iron with higher magnetization contribute maximum MR effect in the MREs composite. Soft elastomer matrix such as rubber matrix could be considered as a most suitable one; however, the vulcanization time is longer that may hinder the durability of the devices. Figure 17: Effect of magnetic flux density on the measured stress-strain hysteresis loops of the MRE as a function of different strain amplitude at 10 Hz: (**a**) 2.5%; (**b**) 5%; (**c**) 10%; and (**d**) 20%. Reprinted from [24], © 2019 with permission from Elsevier. Several cross-linking systems such as sulfurs, organic peroxide, phenolic resins, amino acids, ultrasonic waves, and microwaves have been used for the rubber vulcanization. Among these sulfur and peroxides are the most widely used in the vulcanization process. The mechanism of the accelerated sulfur vulcanization is still controversial partly due to the complexity of the formulation. Therefore, the need to consider the trade-off among MR effects and other performance criteria should be carefully considered for these elastomers. Their application in civil engineering structures, especially for base isolation systems, has recently attracted increasing attention towards adaptive base isolators made of MREs composite. A decrease in the storage modulus as a function of the strain increase, when the filler network is subject to a breakdown, the so-called Payne effect, is shown by all MRE composites, some by more and some by less. In particular, the isotropic MREs show, at low particles content, a systematic decrease in the small-strain storage modulus G' [38; 39]. By contrast, an increase of the small-strain storage modulus \(G^{\prime}\) is generally recorded for the anisotropic MREs. With 30% particle content, anisotropic MRE composite change was more pronounced for the storage modulus (20.4%) than for the loss modulus (8.8%), both changes were determined at 30 Hz with the maximum applied magnetic field being about 0.775 T. This behavior is explained with the magnetized particle arrangement in anisotropic strings during the curing process. The new arrangement that contributes to the stiffness of the compound. Just the micro-sized iron particles, with high saturation magnetization, show a considerable orientation effect within a magnetic field. In fact, due to their large magnetic moment, they generate strong attractive dipole-dipole interactions when the magnetic field is applied [40; 41]. Furthermore, close contact is also decisive to get these dipole-dipole interactions in the magnetic field [42]. MRE's devices are generally classified into two categories, those having either fixed poles (pressure-driven mode) and those having relatively moveable poles (direct-shear mode and squeeze-film mode). The first category includes servo-valves, dampers, and shock absorbers, whilst the second one includes clutches, brakes, chucking, and locking devices.