A Novel Phosphorus/Silicon-Containing Flame Retardant—Functionalized Graphene Nanocomposite: Preparation, Characterization and Flame Retardancy

Abstract

A novel compound (DOPO-V-PA) containing phosphorus and silicon elements was grafted onto the surface of graphene oxide (GO) to obtain a graphene-based flame retardant (GO–DOPO-V-PA). The structure of GO-DOPO-V-PA was characterized and confirmed by FTIR and XPS spectra. AFM measurements showed that the average height of GO-DOPO-V-PA was thicker than that of GO and that the surface of GO-DOPO-V-PA was not uniform, contrary to the surface of the initiator GO before modification. The thermal stability of GO-DOPO-V-PA was greatly improved by the functionalization of GO with DOPO-V-PA, and the residual char of GO-DOPO-V-PA at 600°C increased from 16.45 (GO) to 61.44 wt %. After GO-DOPO-V-PA was incorporated into epoxy resin (EP), the residual char of EP/GO-DOPO-V-PA was almost 3 wt % higher than that of pure EP and EP/GO. Furthermore, EP/GO-DOPO-V-PA exhibited excellent flame retardancy. Compared to the pure EP and EP/GO, the peak heat release rate (pHRR) and total heat release (THR) of EP/GO-DOPO-V-PA both decreased, which was probably caused by the higher residual char of EP/GO-DOPO-V-PA during combustion. Thus, the flame retardancy of the graphene-based composites was improved with the addition of 2 wt % GO-DOPO-V-PA, which was much less than the previously known flame retardant systems, and the graphene has been demonstrated its excellent performance in the fire safety of the polymer materials.