Curing behavior of epoxy/Fe3O4 nanocomposites: A comparison between the effects of bare Fe3O4, Fe3O4/SiO2/chitosan and Fe3O4/SiO2/chitosan/imide/phenylalanine-modified nanofillers

In this study, Fe3O4 magnetic nanoparticles (MNPs) were synthesized (B-MNP) and then modified with SiO2 to form Fe3O4/SiO2 core/shell MNPs. The Fe3O4/SiO2 MNPs were chemically functionalized with chitosan so as to gain Fe3O4/SiO2/Chitosan (CH-MNP). The CH-MNP was functionalized with a macromolecule containing imide and phenylalanine precursors to gain Fe3O4/SiO2/Chitosan/imide/phenylalanine based MNPs (CH-IM-MNP). The differences in chemical structures of the synthesized MNPs were quantified by FTIR and TGA analyses, where grafting ratios of ca. 6 and 28% were calculated for CH-MNP and CH-IM-MNP nanoparticles, respectively. Nanocomposites were prepared by addition of very low (0.1 wt.% nanoparticle based on 100 parts by weight of epoxy) to epoxy/amine systems. Curing behavior of the blank and MNPs-incorporated nanocomposites were studied by nonisothermal DSC analyses varying heating rate, which allowed for giving useful insights into the effect of chemical surface functionalization of MNPs on the curing potential/behavior of epoxy/amine systems. Analysis of fracture surface of the blank and MNPs-incorporated systems using SEM micrographs revealed a very high potential of cure when CH-IM-MNP added to epoxy/amine formulation.