Magnetization-induced reduction in dynamic modulus of polyurethane Elastomers loaded with ferrite

Magnetization effects on the dynamic modulus of a magnetic elastomer consisting of polyurethane and barium ferrite have been investigated. The complex modulus was measured before and after magnetization by dynamic viscoelastic measurements with a compressional strain. Giant reductions in storage modulus of similar to 105 Pa and in loss modulus of similar to 104 Pa were observed after magnetizing the elastomer at 1 T. The magnetic elastomer also showed a deformation with a strain of similar to 10-4 caused by the magnetization. The observed giant reduction in dynamic modulus can be ascribed to the large nonlinear viscoelastic response of the magnetic elastomer and the magnetization-induced deformation. Nonlinear viscoelastic responses, morphologies of magnetic particles, and deformation for the magnetic elastomer are discussed.