RESUMO
High heat generation is reported in core-shell magnetic nanoparticle polystyrene (PS) nanocomposites (3.5, 10 wt %) when they are placed in a high-frequency ac magnetic field. These magnetic nanoparticles with cobalt iron oxide core and manganese iron oxide shell were synthesized and characterized by wide-angle X-ray scattering (WAX), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), and ac field gradient magnetometery. When placed in a high-frequency ac magnetic field, the thermal energy generated in the magnetic polystyrene nanocomposites resulted in a surface temperature increase. The heat generation is attributed to the contribution of Néel relaxation and hysteresis of the core-shell magnetic nanoparticles in the solid state. The maximum surface temperature increased with increasing nanoparticle content and resulted in melting of the magnetic polystyrene nanocomposite.
