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 ∼10 5 Pa and in loss modulus of ∼10 4 Pa were observed after magnetizing the elastomer at 1 T. The magnetic elastomer also showed a deformation with a strain of ∼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.