Effects of Magnetization on Dynamic Modulus of Magnetic Gels

Abstract

Effects of magnetization on the complex modulus of magnetic gels have been investigated. The magnetic gel was made of natural polymers of κ-carrageenan and ferromagnetic particles of barium ferrite BaFe₁₂O₁₉. The volume fraction of the ferrite was varied up to 38 vol.%. Complex moduli of the magnetic gel were measured by dynamic viscoelastic measurements with a compressional strain. Storage modulus of the magnetic gel as obtained increased with increasing the volume fraction of ferrite. The magnetic gel was magnetized by applying the magnetic field of 1T. It was firstly observed that the storage modulus after being magnetized decreased compared to the modulus before one. The change in the modulus increased with increasing the ferrite volume fraction and it exceeded beyond 75% of the modulus before being magnetized. It was also found that the change in the modulus was nearly independent of a magnetization direction.