Significantly enhancing fracture toughness of epoxy composite with promising γ-FeOOH@Fe2O3 hybrid nanoparticles by magnetic field assistance

Abstract

Abstract The toughening of epoxy resin (EP) and the interlaminar toughening of carbon fiber reinforced composite (CF/EP) laminates have been widely concerned. In this work, the needle-like γ-FeOOH nanoparticles were prepared by liquid phase deposition-air oxidation method, and then were calcined under different conditions to obtain γ-FeOOH and γ-Fe2O3 hybrid nanoparticles (γ-FeOOH@Fe2O3). Effect of calcination condition of γ-FeOOH@Fe2O3 and magnetic field assistance on fracture toughness (KIC) of EP was systematically investigated. Then the selected γ-FeOOH@Fe2O3 with the best toughening effect were used to improve the mode I interlaminar fracture toughness (GIC) of CF/EP laminate. The resulting γ-FeOOH@Fe2O3 have a length of around 1\xa0\u200bμm, a diameter of around 100\xa0\u200bnm and the Ms of 8.99–45.96 emu/g. After calcinated at 250\xa0\u200b°C for 1\xa0\u200bh, the γ-FeOOH@Fe2O3 containing 24\xa0\u200bwt% FeOOH and 76\xa0\u200bwt% Fe2O3 achieved the best toughening effect. Under a magnetic field of 0.09\xa0\u200bT, the KIC of the γ-FeOOH@Fe2O3/EP composite (2.45\xa0\u200bMPa\xa0\u200bm1/2) is 81.7% and 66.7% higher than that of neat epoxy and the composite without magnetic field induction, respectively. Furthermore, the GIC of the γ-FeOOH@Fe2O3/CF/EP composite (0.914\xa0\u200bkJ/m2) is also significantly increased by 88.8% and 51.8% compared to that of CF/EP and the corresponding composite without magnetic field induction, respectively.