Effect of secondary particles on the microstructure and mechanical properties of magnetorheological plastomers

•MRPs doped with three kinds of secondary particles are prepared and tested.•MRPs with different secondary particles show conflicting mechanical properties.•The internal particle structures with different secondary particles are simulated. Magnetorheological plastomers (MRPs) with two different types of fillers have attracted considerable attention for various advantages. However, the effect of secondary particles on mechanical properties is still under controversy due to its conflicting behaviors. In this work, MRPs with three kinds of secondary particles were prepared and their mechanical properties were systemically investigated. The experimental results showed the incorporation of glass balls (20 μm in diameter) led to an increase in the mechanical properties. By contrast, SiO2 and Fe3O4 particles (1 μm in diameter) showed a conflicting behavior. With the increase of secondary particle content, for MRP with SiO2, the storage modulus first increased and then decreased. But for MRP with Fe3O4, the storage modulus first decreased slightly and then increased. At last, the microstructures in MRPs were simulated by a particle-level dynamic method to investigate the effect of secondary particles on the microstructure and mechanical properties of MRPs.