Magnetic field-induced orientation of Fe3O4-GO and toughening effect on epoxy resin

Magnetic nanoparticle-coated graphene oxide (GO) can be oriented in polymers under magnetic field due to the anisotropy of GO and excellent magnetism of magnetic nanoparticles. In this study, ferroferric oxide nanoparticles coated GO (Fe3O4-GO) was synthesized successfully using oxidation-coprecipitation method. The synthesized Fe3O4-GO was then added to epoxy and oriented by applying magnetic field using (1) the electromagnetic coil and (2) permanent magnets to toughen the epoxy matrix. Non-isothermal differential scanning calorimetry (DSC) tests were performed to determine the curing process of Fe3O4-GO/E-51/3a-methyl-5,6-dihydro-4H-isobenzofuran-1,3-dione (MeTHPA)/2,4,6 Tris(dimethyl aminomethyl)phenol (DMP-30) system (Fe3O4-GO/E-51/MeTHPA/DMP-30). Transmission electron microscope images show that Fe3O4 nanoparticles were coated on the GO surface homogenously and Fe3O4-GO were highly oriented in E-51/MeTHPA/DMP-30 epoxy system under different magnetic field conditions. The maximum impact strength of Fe3O4-GO/E-51/MeTHPA/DMP-30 composite was observed at 0.2 wt% Fe3O4-GO loading, with values of 28.64 and 30.54 kJ/m(2) in case of the magnetic field applied through permanent magnets and electromagnetic coil respectively, which is an increase by 39.6 and 48.8% respectively when compared with the pure E-51/MeTHPA/DMP-30 system (20.52 kJ/m(2)). In addition, at 0.4 wt% Fe3O4-GO loading and application of magnetic field through electromagnetic coil, the maximum increase in flexural modulus was observed, which was increased by 41.8% and 17.23% compared with the pure epoxy system and the one without application of magnetic field at same Fe3O4-GO loading respectively. The fracture morphologies from the scanning electron microscope also indicated that the oriented Fe3O4-GO under magnetic field improved the toughness of the E-51/MeTHPA/DMP-30 resin system.