(654e) Reinforced Magnetic Epoxy Nanocomposites with Conductive Polypyrrole Nanocoating on Nanomagnetite As a Coupling Agent

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. Compared with pure epoxy suspension, the viscosity of epoxy nanosuspensions with 5.0 and 10.0 wt% f-Fe₃O₄ nanoparticles is almost the same. The glass transition temperature (T_g) of cured solid epoxy polymer nanocomposites (PNCs) with 30.0 wt% f-Fe₃O₄ nanoparticles is 22.3 ^oC higher than that of cured pure epoxy (88.2 ^oC) in the dynamic mechanical analysis (DMA).¹ Compared with the tensile strength of 83.0 MPa for the cured pure epoxy,² the enhanced mechanical tensile strength of 91.7 MPa observed in the cured epoxy PNCs with 5.0 wt% f-Fe₃O₄ nanoparticles is attributed to the introduced interfacial interaction between the nanoparticles and the hosting epoxy matrix through the existed PPy nanocoating as observed in the fracture surface. The volume resistivity of the cured epoxy PNCs with 30.0 wt% f-Fe₃O₄ nanoparticles is decreased almost 7 orders of magnitude compared with the cured pure epoxy (1.6×10¹³ Ω cm). The cured epoxy PNCs exhibit good magnetic properties, the surface functionality and epoxy have little effect on the magnetic moment of the Fe₃O₄ nanoparticles. The role of PPy nanocoating on the nanocomposites formation mechanism was investigated by using the FT-IR and TGA tests. The cured epoxy PNCs with f-Fe₃O₄ nanoparticles show positive permittivity, and the permittivity increases with increasing the particle loading. Highly efficient electromagnetic field absorption at gigahertz (GHz) was reported in the epoxy nanocomposites with 30.0 wt% f-Fe₃O₄ nanoparticles, a minimum reflection loss (RL) of −32.0 dB was observed at 8.46 GHz, and the frequency bandwidth with RL lower than −10.0 dB was 3.2 GHz (from 11.6 to 15.2 GHz) in the MPNC sample with a thickness of 1.8 mm.