Curing epoxy with electrochemically synthesized NixFe3-xO4 magnetic nanoparticles

Abstract

Fe3O4 magnetic nanoparticles (MNPs) were synthesized via cathodic electrodeposition in the form of undoped and Ni2+-doped MNPs, and their curing potential towards epoxy was discussed. Partial substitution of Fe2+ sites by Ni2+ cations in the general formula of NiXFe3-XO4 was confirmed by – X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), dispersive X-ray spectrometry (EDS), and vibrating sample magnetometry (VSM). Low-filled epoxy/Fe3O4 and epoxy/Ni2+-Fe3O4 nanocomposites containing 0.1 wt.% MNPs based on 100 parts by weight of epoxy resin were prepared and underwent nonisothermal differential calorimetry (DSC) at different heating rates (5, 10, 15, and 20 °C/min). The curability of the well-characterized nanocomposites of epoxy/Ni0.11Fe2.89O4 was qualitatively studied by the use of Cure Index. Overall, structural changes in Fe3O4 atomic structure resulting from the replacement of Fe2+ cations with Ni2+ had effect on epoxy curing reactions, as reflected in a shift in curing state from Poor for epoxy/Fe3O4 to Good for epoxy/Ni2+-doped Fe3O4 systems. This phenomenon was explained on account of the fact that Ni2+ dopants with their laminar structure tend to locate in the top layer of Fe3O4, which dramatically increases the activity of Fe3O4 to take electron pair of epoxy to open epoxy ring.