Magnetically sensitive nanocomposites based on the conductive shear-stiffening gel

Abstract

In this paper a novel multi-functional composite with high electrical conductivity and excellent magnetic field sensitivity was fabricated by embedding carbon nanotubes (CNTs) and carbonyl iron powders (CIPs) into shear-stiffening gel (STG). Oscillatory shear test demonstrated its excellent rheological properties. When the mass fractions of CNTs and CIPs were 1 wt% and 50 wt%, the increase in storage modulus (G′) reached 585% under 100 Hz oscillatory shear and 428% under 1.2 T magnetic flux density with respect to its initial state. The resistivity of this CNT–CIP–STG composite achieved 25 Ω m and showed strong dependence on the magnetic field. When the external magnetic flux density was 873 mT, the normalized electrical resistance response reached up to − 40.5%. Linearly increasing and step magnetic field was employed to study the electrical and mechanical behaviors of this CNT–CIP–STG composite. The instantaneous response and time effect were discussed. Interestingly, oscillatory shear showed limited influence on the electrical conductivity but notable enhancement on the sensitivity to magnetic field. A mechanic–electric coupling mechanism was proposed to illustrate enhancement of shear thickening effect and sensibility to magnetic field.