| Magnetorheological elastomers (MREs) fall in the class of smart materials, due to its controllable rheological properties. Their rheological properties can be continuously, rapidly, and reversibly changed with the application of a magnetic field, which makes this material of high interest, due to its real-time magnetorheological response. However, conventional MREs currently have mechanical properties that are rather low due to its matrix material and third interphase (the phase between the iron particles and the matrix). In order to alter the mechanical properties of the matrix material, the ratio between agent and base of the matrix materials are changed to determine the change in stiffness and damping properties. Additionally, the elastomer was altered by adding in acetone during the fabrication process; the addition of acetone would de-bond the connection between the iron particles and the matrix which would result in higher damping properties without compromising the stiffness of the material. Furthermore, because carbon nanotubes have high stiffness, strength, and surface area, the magnetorheological elastomer increased in both stiffness and damping; the CNT increases the stiffness of the MRE as a result of their mechanical properties, while increasing the damping of the MRE because of the higher amount of third interphase that is generated (which causes sliding friction to be released as heat). Firstly, the novel MR nanocomposite was fabricated, with their microstructure and dynamic viscoelastic properties subsequently characterized via scanning electron microscope (SEM), 3D X-ray microscope, and dynamic mechanical analysis (DMA). Through dynamic testing and microscopic evaluation of the material, it has been observed that for MR nanocomposites that were composed of carbon nanotubes exhibited both a higher zero-magnetic field stiffness and damping properties compared to conventional MREs; additionally, the MR nanocomposites had a higher magnetic-field-induced increase in both the stiffness and damping properties. Furthermore, it was seen that with an increase in agent-to-base ratio, the elastomer exhibited a higher initial stiffness; however, it also displayed a lowering in damping properties. Finally, when the magnetorheological material (both elastomer and nanocomposite) had acetone introduced during the fabrication process, the damping properties increased when compared to the same magnetorheological material with no acetone. In an effort to understand how MR elastomers are affected by the fabrication process, research will be done in characterizing the composition of elastomers. This includes determining how iron particles within the matrix are altered with the introduction of a magnetic field during curing, and density distribution of the elastomer. Furthermore, the effects of acetone and carbon nanotubes on the elastomer will be determined. The process will include the use of scanning electron microscope and three-dimensional x-ray imaging. |
