Effect of alignment of magnetic particles on the rheological properties of natural rubber composite

Rheological properties of a natural rubber based magnetorheological elastomer (MRE) with spherical carbonyl iron particles (CIPs) and plate-like Sendust particles as soft magnetic particles were investigated. Isotropic and anisotropic MRE samples were prepared by molding in the absence or presence of magnetic field. Different shape of magnetic particles provided significant effect on mechanical properties of the MRE samples. The rheological properties of the MRE samples were measured in shear mode through a modified Dynamic Mechanical Analysis system equipped with an electromagnet. MRE samples containing plate-like Sendust particles showed higher shear storage modulus than MRE samples with spherical CIPs. Isotropic structures of the two types of magnetic particles contributed to improvement in MRE's performance, such as absolute and relative MR effect. The relative MR effect had a strain-dependent behavior that increased with increasing strain amplitude due to the Payne effect.