Effects of surface morphology and treatment of iron oxide nanoparticles on the mechanical properties of an epoxy coating

Iron oxide nanoparticles with fiber-like and polygon morphologies were synthesized in the presence of triethanolamine and urea surfactants. The synthesized particles were then treated by 3-amino propyl trimethoxy silane (APTMS). Then, the nanocomposites were prepared through incorporation of 1 wt.% unmodified and surface modified nanopigments into the epoxy resin. The phase composition and morphology of the nanoparticles were characterized by X-ray diffraction (XRD) and field-emission scanning electron microscope (FE-SEM); respectively. The chemical grafting of silane chains on the surface of nanoparticles was studied by Fourier transform infrared spectroscopy (FT-IR). The mechanical properties and fracture morphology of the nanocomposites were investigated by tensile test. SEM and XRD analyses revealed that surfactants significantly affected the size and morphology of the nanopigments. FT-IR analysis confirmed chemical functionalization of APTMS chains on the surface of nanopigments. It was found that surface treatment of nanoparticles by APTMS effectively improved the compatibility and dispersion of particles in the epoxy matrix. The nanoparticle synthesized in the presence of urea increased the fracture toughness and tensile strength of the composite greater than the nanopigment synthesized in the presence of triethanolamine. Results obtained from tensile test revealed the noticeable improvement of the interfacial interactions between Fe3O4/APTMS particle and epoxy matrix. Inclusion of surface modified nanopigments into the epoxy coating resulted in higher tensile strength and fracture toughness compared to the coating filled with unmodified nanopigments. It was found that the morphology and surface chemistry of the nanopigment significantly affected the mechanical properties of the epoxy coating. (C) 2015 Elsevier B.V. All rights reserved.