Anisotropic behaviour analysis of silicone/carbonyl iron particles magnetorheological elastomers

We report the microscopic, magnetic and rheological properties of magnetorheological elastomers (MRE) with carbonyl iron magnetic particles (CIP) dispersed into silicone in the concentration range 5–30% volume content. The samples have been fabricated under the action of a magnetic field (anisotropic A-MRE) or without it (isotropic I-MRE). For the A-MRE samples and at low particle concentration, the anisotropy is evident in the microstructure and the magnetic properties. However and at high particle concentration, the microstructural and magnetic anisotropy is much less noticeable and makes difficult to distinguish between isotropic and anisotropic state. The rheological characterization shows changes in the storage modulus G ′ when CIP content is from 5 to 30% volume and I-MRE (72% change) and A-MRE (70% change) character of the samples. However, this influence is remarkable in the loss modulus G ″ with big changes when considering CIP content from 5 to 30% volume and I-MRE (114% change) and A-MRE (142% change). We have also determined that the anisotropic samples with high particle content present the maximum magnetorheological effect of about 31% at low frequency (1–2 Hz).