On the oscillating shear rheometry of magnetorheological elastomers

Critical issues of the oscillating shear rheometry with disc-shaped elastomer specimens are exemplified. A torsional oscillation method to characterise magnetorheological elastomers (MREs) using a rheometer is introduced and compared to the standard procedure with disc-shaped specimens. Advantages and disadvantages of the method are identified. It is shown that the rheometry with rod-like specimens provides more reliable data, which are easier to reproduce. The method also allows characterisation of MREs in a not pre-strained condition, an aspect which importance is demonstrated. Moreover, it opens an easy way to characterise permanently magnetised MREs with a complex composition using conventional rheometers.