Giant and reversible magnetorheology of carrageenan/iron oxide magnetic gels

The effect of magnetic fields on the viscoelastic properties, the magnetorheological effect, of carrageenan gel containing iron oxide particles has been investigated using dynamic viscoelastic measurements under magnetic fields. The carrageenan concentration was varied in order to prepare magnetic gels with various storage moduli. Significant change in the storage modulus was not observed when the carrageenan concentration was 2 wt%; however, the magnetorheological effect appeared on decreasing the concentration. The maximum change in the relative storage modulus was 24 when the carrageenan concentration was 0.6 wt%. The loss tangents of the magnetic gels also altered in response to the magnetic field as well as the storage moduli. The relationship between the magnetorheology and the elasticity of magnetic gel is discussed.