Curing epoxy with electrochemically synthesized Co_xFe_{3- x}O₄ magnetic nanoparticles

Electrochemical method was utilized in one-pot synthesis of Fe₃O₄ magnetic nanoparticles (MNPs), and also cobalt (Co)-doped MNPs in which Co²⁺ cations were exchanged partially with Fe²⁺ in the ferrite structure. Different techniques including vibrating sample magnetometry (VSM), X-Ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy were used in characterization of MNPs’ structural changes. Well-characterized nanoparticles were then incorporated into epoxy/amine system to study their curing potential on the ground of the effect of Fe²⁺ and Co²⁺ cations. A very low amount of MNPs was applied in preparation of epoxy/Fe₃O₄ and epoxy/Co²⁺-Fe₃O₄ nanocomposites to comparatively infer the sensitivity of epoxy curing reaction to Fe²⁺ and Co²⁺ cations. Nonisothermal DSC was utilized under different heating rates to evaluate curability of nanocomposites in terms of Cure Index. Overall, the amount of heat released in the course of curing of nanocomposites containing Co²⁺-doped MNPs was significantly higher than that for epoxy/MNPs system, demonstrating that Co²⁺ doping improves the curing reaction between epoxy and curing agent. This was qualitatively approved by a shift seen from Poor to Good cure, particularly at lower heating rates, demonstrated by the Cure Index.