Effect of Filler Morphology on Viscoelastic Properties of PDMS-Based Magnetorheological Elastomers

Abstract

ABSTRACTThe viscoelastic properties of magnetorheological elastomers (MREs) are tunable with an external magnetic field, which provides them with greater functionality than conventional reinforced polymers. Despite the abundant amount of literature studying the complex micromechanics of MREs, the effect of filler morphology (including particle size, shape and superficial texture) is an aspect that has been recurrently overlooked. This paper presents a multiscale experimental investigation of the microscopic mechanisms governing the macroscopic viscoelastic behavior of PDMS-silicone-based MREs, with an emphasis on the effect of filler morphology on both the microstructure and the overall dynamic shear response of MREs. Sixteen different MREs were produced using four different iron powders of varying average particle size, shape and texture. The morphology of iron particles and the microstructure of the fabricated materials were analyzed via X-ray computed nanotomography and scanning electron microscopy. In addition, the shear moduli of the specimens were monitored under coupled magneto-mechanical loading via dynamic mechanical analysis. This study shows that the particle size affects the strength of the magnetic interparticle interactions, which produce a confining effect on the rubber matrix, while the particle shape and texture have a great influence on the rubber-filler mechanical adhesion.