Magnetorheological behaviour of magnetic carrageenan gels against shear and compression strains

Magnetic field effect on the elasticity was investigated for magnetic carrageenan gel when a shear and compressional deformation was applied to the gel. The magnetic carrageenan gel consists of carrageenan of a polysaccharide, and carbonyl iron particles. The dynamic viscoelastic measurement with shear strain revealed that the storage shear modulus of the gel increased from 1.0x10(4) to 2.3x10(6) Pa by applying a magnetic field of 320 mT. On the other hand, the compression measurement showed that the Young's modulus increased from 6.2x10(4) to 5.9x10(5) Pa. The relative changes in the modulus with respect to the original modulus were 230 for shear strain and 9.5 for compressional strain, respectively. This strongly indicates that the magnetic field effect on viscoelasticity strongly depends on the geometry of directions of magnetic field and strain. The effect of vibration suppression of the present gel tuned by magnetic field is also presented.