Magnetic and electric effects in magnetorheological suspensions based on silicone oil and polypyrrole nanotubes decorated with magnetite nanoparticles

Abstract

In this work, two magnetorheological suspensions composed of polypyrrole nanorods decorated with magnetite nanoparticles and suspended in silicone oil were studied as electrical devices. The electrical devices (EDs) were fabricated in a unique cell using nanotubes with different magnetic and electric properties which can be tailored during synthesis. The electrical effects of the suspensions were studied under static electric and magnetic fields and were superimposed on a medium-frequency electric field. The electrical resistance Rp and the quality factor Qp at the terminals of EDs were extracted and analysed. Additionally, the equivalent electrical capacitances Cp were obtained through a well-established theory and then compared for each ED. Through the electrical and magnetic dipolar approximation model, it was illustrated that the electrical effect induced in a suspension can be three times higher depending on the amount of the magnetite. Thus, by tuning the synthesis parameters, it is possible to obtain EDs with well-defined and unique properties.

Keywords

• Magnetorheological suspensions
• Polypyrrole nanotubes
• Magnetite nanoparticles
• Relative dielectric permittivity
• Dielectric loss factor
• Active magnetic composites