The Effect of the Silicon Shell of Magnetic Microparticles on the Viscoelastic Properties of Magnetoactive Silicone Elastomers and Their Response to an External Magnetic Field

Magnetic microparticles with silicon shells of varying thickness have been obtained by modifying the surface of carbonyl iron. The structure and magnetic properties of the particles have been studied using scanning electron microscopy and vibrational magnetometry. The original and modified particles have been used as fillers to create magnetoactive elastomers based on polydimethylsiloxane. The concentration of magnetic particles in the magnetoactive elastomers varied from 40 to 80 wt %. Dynamic mechanical analysis showed that the initial shear storage moduli of the samples ranged from 5 to 25 kPa, increasing with increasing filler concentration and reaching values of approximately 400 kPa when a magnetic field was applied. At an equal particle volume fraction, the presence of the shell leads to a decrease in the storage modulus of the samples. In a magnetic field, samples with an equal fraction of iron but different thicknesses of the nonmagnetic shell demonstrate approximately the same storage moduli in the region of low particle concentration values; in the region of intermediate values, the presence of the shell leads to an increase in the storage modulus, and in the region of high values, to its decrease.