Smart magneto-responsive carbonyl iron/natural rubber composites and their viscoelasticity

초록

Magnetorheological (MR) elastomers are solid analog of MR fluids whose viscoelastic properties can be finely altered by a magnetic field strength applied. MR elastomers consist of magnetic particles such as carbonyl iron (CI) and iron oxide in an elastomer matrix such as natural rubber and silicone rubber. In this study, we examined effect of CI particle grade and particle orientation on their MR properties. To confirm the orientation of the magnetic particles of the CI/ natural rubber elastomer composite, a mapping method through scanning electron microscope was used. Rheological properties of the MR elastomers under magnetic field were investigated by a rotational rheometer equipped with a magnetic field supplier. Dynamic moduli of the MR elastomer samples, indicating the viscoelastic properties of the samples, were obtained from both strain amplitude and frequency sweep tests. The results showed that as the magnetic field strength increases, the storage moduli increased depending on the angular frequency at a constant shear strain. Higher MR performance from both the viscoelastic characteristics and MR efficiency were also observed for the anisotropic MR elastomer compared to the isotropic MR elastomer. Their MR efficiency and damping factor were also investigated.