The effect of silane coupling agent on the dynamic mechanical properties of iron sand/ natural rubber magnetorheological elastomers

Isotropic and anisotropic magnetorheological elastomers (MREs) containing unmodified and silane modified iron sand particles in a natural rubber matrix were prepared. Tan δ and the amount of energy dissipated during cyclic deformation were used as the parameters to assess damping. Tan δ was measured through dynamic mechanical analysis over a range of frequency (0.01-130 Hz), strain amplitude (0.1-4.5%) and temperature (−100-50 °C). Energy dissipated was measured using a universal tester under cyclic tensile loading. The silane coupled improved the amount of energy dissipated during hysteresis tests as well as tan δ over the range of frequency and strain amplitude explored and tan δ increased with increasing magnetic field up to a saturation point at 600 mT. However, the presence of coupling agent and formation of different lengths of aligned particles did not strongly affect the value of Tg and maximum tan δ at Tg. Evidence from scanning electron microscopy (SEM) supported that the use of modified iron sand does not interfere with the formation of magnetic particles chains in the matrix during curing and the chains became longer and more aligned as the magnetic field strength increased.