Effect of the carbonyl iron particles on damping properties of magnetorheological elastomers based on natural rubber

Abstract

This paper aimed to investigate damping properties of two groups of Magnetorheological Elastomers (MREs) based on natural rubber with 60 wt% iron particles as isotropic and structured MREs. Therefore, the influences of a variety of fabrication conditions on the MREs performances, such as carbonyl iron particle size, external magnetic field and frequency were studied. Moreover, the damping property of MREs with reference sample which contains 60wt% carbon black instead of iron particles was compared. Also, the microstructures of both isotropic and structured MREs were investigated using an environmental scanning electron microscope (SEM) and finally, the damping properties of MREs were measured by using a modified dynamic mechanical thermal analyzer (DMTA) applying magnetic field and without applying magnetic field. The results illustrated that the loss factors of structured MREs were lower than isotropic MREs. In addition, the loss factors increased with applying magnetic field for MREs with large sized particles and didn’t change for MREs with small sized particles. The results also indicated that the loss factor of the reference sample was 43% higher than MREs and the difference had been lowered to 15% by applying external magnetic field of 1.3 T. The storage modulus of MRE samples decreased with applying external magnetic field and the storage modulus of structured MRE was much higher than isotropic MRE when no magnetic field applied. However, the storage modulus of both isotropic and structured samples was the same with applying magnetic field. The analysis implied that the interfacial friction damping mainly comes from the frictional sliding at the interfaces between the free rubber and the particles.