Ternary Multifunctional Composites with Magnetorheological Actuation and Piezoresistive Sensing Response

Abstract

Advances in the development and implementation of magnetorheological elastomers (MREs) have demonstrated their potential for vibration control and damping, among others. To increase further the applicability of MREs, the present work reports on MREs with piezoresistive self-sensing characteristics by adding conductive fillers. Multifunctional MREs are thus reported based on the styrene–ethylene–butylene–styrene (SEBS) polymer matrix with embedded Fe3O4 nanoparticles as magnetically responsive materials and multiwalled carbon nanotubes (MWCNT) as conductive fillers. Specifically, SEBS-based composites with a constant 20 wt % Fe3O4 content and different concentrations of MWCNT have been prepared. The effect of MWCNT addition on the morphological, mechanical, electrical, magnetorheological, and piezoresistive properties of the MRE-based composites was explored. Increasing MWCNT filler content leads to an increase of the Young’s modulus and maximum elongation of the composite. All samples show a notable MR effect, a maximum MR response of 9% being obtained for the 5 wt % MWCNT sample. Moreover, the addition of MWCNT leads to an increase of the electrical conductivity of the composite by 12 orders of magnitude, with a percolation threshold around 0.17 wt % MWCNT. Further, a maximum piezoresistive response characterized by a gauge factor of 6.5 is obtained for the composite with 5 wt % MWCNT content. The developed ternary multifunctional materials that combine simultaneously magnetorheological and piezoresistive properties represent a generation of magnetorheological actuators with self-sensing deformation capability.