Influence of functionalized graphene by grafted phosphorus containing flame retardant on the flammability of carbon fiber/epoxy resin (CF/ER) composite

In this paper, the graphite oxide was prepared by modified Hummers method, and 9,10-dihydro-9-oxa -phosphaphenanthrene-10-oxide (DOPO) was grafting on the graphene by acylating chlorination method to prevent aggregate and gain synergistic flame retardancy. Graphene-DOPO was characterized by fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Carbon fiber/epoxy resin (CF/ER) composites containing graphene-DOPO were prepared by hot pressing method. And the flammability properties of the composites were investigated. Composites with 3 wt% graphene-DOPO increased the LOI value from 18.5% to 28%and can reach UL-94 V-1rating during the vertical flame tests. Moreover composites with 3 wt% graphene-DOPO reduced the total heat release (THR) from 16.1 to 12 kJ/g. The same tendency was acquired from the peak heat release rate (PHRR) showing positive effect of graphene-DOPO in improving the flame retardancy of CF/ER composites. TGA results demonstrated that the char residues of composites increased with the addition of graphene-DOPO.