New magnetorheological elastomers based on polyurethane/Si-rubber hybrid

A type of magnetorheological elastomer based on polyurethane (PU)/silicone rubber (Si-rubber) hybrid was fabricated without applying a magnetic field. The MR effect was improved by optimizing preparation conditions, in particular by adjusting the PU/Si-rubber ratio, and improving compatibility between PU and Si-rubber. The influences of the preparation conditions and the relationship between the microstructure and MR effect of this kind of magnetotheological elastomer are discussed in detail. The results show that this kind of MR elastomer has better MR effect than that of MR elastomers based on pure Si-rubber or PU matrix with the same testing conditions. SEM analysis indicates that the former forms a peculiar interpenetrating microstructure in the presence of PU in the matrix. The maximum increase in shear modulus of this kind of MR elastomer can be up to 0.5 MPa when exposed to a magnetic field of about 0.2 T. (c) 2004 Elsevier Ltd. All rights reserved.