Frequency-Dependent on the Magnetorheological Effect of Magnetorheological Plastomer

A low cross-linked magnetic polymer matrix also known as magnetorheological plastomer (MR plastomer) containing micron-sized carbonyl iron particles (CIPs) is a new kind of MR materials. MR plastomer can be prepared by two main methods which are physically and chemically crosslinking. However, the study on the dynamic properties of involving chemically crosslinked MR plastomer particularly the viscoelastic properties especially frequency-dependent are not systematically investigated. Therefore, in this study, the effect of the frequency on the MR effect and damping performance of chemically crosslinking MR plastomer under oscillatory modes condition were analysed. The magnetic particles namely CIPs were inserted into a plasticine-like polymer matrix causing the materials to exhibit an MR effect in response to an external magnetic field. Polymer base matrix was prepared using poly-vinyl alcohol (PVA), and boric acid (BA) was used as a cross-linking agent for chemically crosslinked MR plastomer. The MR plastomer samples were prepared using 70 wt% of CIPs as magnetic particles. The samples were tested using a rheometer with different test frequencies, which are 1, 5, and 10 Hz at the on-state condition. The experimental results revealed that the frequency has a significant correlation with the MR effect of samples where the MR effect of the sample decreased with the increment of test frequency. The MR effect for each sample at 1, 5, and 10 Hz are 6793, 5049, and 3131% respectively. In contrast, for the frequency sweep test, the storage modulus of the sample showed an increasing trend with the increment of test current, while the loss factor revealed an opposite result. The results proved that this kind of MR materials has the potential to be used in various of applications like soft actuator, vibration absorber, and force sensor.