Reinforced magnetic epoxy nanocomposites with conductive polypyrrole nanocoating on nanomagnetite as a coupling agent

Abstract

The new function of polypyrrole (PPy) to serve as a coupling agent has been demonstrated in preparing conductive epoxy resin nanocomposites with PPy coating on magnetite (f-Fe₃O₄) nanoparticles. The effects of magnetic nanofiller loading level on the rheological behavior, thermal stability, dynamic mechanical properties, mechanical properties, electrical conductivity, dielectric properties and magnetic properties were systematically studied. Compared with pure epoxy suspension, a reduced viscosity was observed in epoxy nanosuspensions with 5.0 wt% f-Fe₃O₄ nanoparticles, and the viscosity increased with further increasing f-Fe₃O₄ nanoparticle loading. Increased glass transition temperature (T_g) and enhanced mechanical tensile strength were observed in the cured solid epoxy polymer nanocomposites (PNCs) with f-Fe₃O₄ nanoparticles. The volume resistivity of the cured epoxy PNCs with 30.0 wt% f-Fe₃O₄ nanoparticles was decreased almost 7 orders of magnitude compared with the cured pure epoxy (1.6 × 10¹³ Ω cm). The cured epoxy PNCs exhibited good magnetic properties, and the surface functionality and epoxy matrix have little effect on the magnetic moment of the Fe₃O₄ nanoparticles. The role of PPy nanocoating on the nanocomposite formation mechanism was investigated by using the Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) tests.