Chapter 13 - Magnetorheological studies of polymer nanocomposites

Abstract

Recently, magnetorheological (MR) materials such as MR fluids (MRFs), MR elastomers (MREs), MR grease (MRG), and MR foams, have been considered in diverse industrial and academic areas owing to their quick response to the applied magnetic or electric fields. These characteristics aid to control over rheological properties of such materials with adjusting the strength of applied magnetic or electric fields. Among all, MREs have gained more interest because of their high research potential in the engineering field, especially for automotive application, radiation, military-related system, and rehabilitation fields. In fact, MREs mainly consist of rubber as a matrix and ferromagnetic particles in the presence of additives. The most noticeable feature of MREs is their desirable performance owing to the stability of magnetizable particles in the matrix. However, this feature is challenging because of the particle sedimentation over long-term use. Thus, to improve their magnetorheological properties, composite parameters must be controlled and scrutinized. Indeed, the matrix selection plays an important role in the development of MRE devices application by contributing to the mechanical and rheological behavior. This, in turn, would affect their design and performance. Several types of rubber, including natural rubbers, thermoplastics, and silicone rubbers, are widely used as matrix. Besides, in terms of magnetic particles, their type, size, shape, and volume fraction play significant roles on the rheological characteristics and as a consequence on their performances. Fillers or additives are incorporated into polymer-based composite materials mainly to improve processing ability, reduce the material cost, or achieve desired properties. In this chapter, MR materials and composite MREs will be introduced in detailed with emphasis on the different components and various preparation methods, which will be followed by investigation of their physicochemical and mechanical properties.