Ionic liquid modified graphene oxide for enhanced flame retardancy and mechanical properties of epoxy resin

Abstract

AbstractIn this work, to improve its dispersion and flame retardancy, graphene oxide (GO) was functionalized by silane coupling agent KH550 and 1‐butyl‐3‐methylimidazole hexafluorophosphate (PF6‐ILs), and characteristics of the PF6‐ILs@GO was obtained by transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and thermogravimetric analysis (TGA). Then, the synergistic flame retardant of GO or PF6‐ILs@GO and melamine pyrophosphate (MPP) were applied for epoxy resin (EP) materials. Specifically, the limiting oxygen index (LOI) value of EP with 0.1 wt% PF6‐ILs@GO was increased to 29.2% from 27.5% of EP/MPP composites, and the UL‐94 test reached the V‐0 rating. The CCT results showed that the total heat release (THR) and total smoke release (TSP) of EP/MPP/PF6‐ILs@GO composites were significantly 24.4% and 53.4% lower than that of EP/MPP composites. Besides, the thermal behavior investigated by TGA indicated that the char‐forming effect of GO and PF6‐ILs@GO was great, the residual char of EP/MPP/PF6‐ILs@GO composites was as high as 19.5% at 700°C, and its thermal stability was higher than that of EP/MPP composites. On the other hand, the tensile strength of EP/MPP/GO and EP/MPP/PF6‐ILs@GO composites were increased by 15.6% and 28.3% compared with EP/MPP composites. According to SEM analysis, the EP/MPP/GO composites formed a good protective char layer, which can effectively improve flame retardancy of EP. This research represents a new method of flame retardant modified GO to improve the flame retardancy and mechanical properties of polymers.