Hyper-branched polymer grafting graphene oxide as an effective flame retardant and smoke suppressant for polystyrene

Highlights: • A well-defined functionalized graphene oxide (FGO) grafted by hyper-branched flame retardant based on N-aminoethyl piperazine and phosphonate derivative was synthesized. • The FGO nanosheets were well-dispersed in PS matrix according to TEM observation. • The incorporation of FGO into PS matrix effectively improved the flame retardancy and restrained the toxicity of the volatiles escaped. • The functionalized GO with the hyper-branched flame retardant presented herein provide an effective strategy to reduce the fire hazards (including both heat hazard and non-heat hazard) of the PS materials. - Abstract: A well-defined functionalized graphene oxide (FGO) grafted by hyper-branched flame retardant based on N-aminoethyl piperazine and phosphonate derivative was synthesized to reduce flammability and toxicity of polystyrene (PS). The chemical structure, morphological and thermal properties were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and thermogravimetric analysis, respectively. Micro combustion calorimeter and steady state tube furnace were employed to evaluate the heat and non-heat fire hazards of PS nanocomposites. The incorporation of FGO into PS matrix effectively improved the flame retardancy and restrained the toxicity of the volatiles escaped, which is attributed to that the homogeneous dispersion of FGO in the PS matrix enhanced barrier effect that reduced peak heat release rate, total heat release and toxic gas release during combustion. Furthermore, PS-FGO nanocompsites obviously decreased the amount of flammable and toxic volatiles evolved, such as the aromatic compounds, carbonyl compounds, carbon monoxide, indicating suppressed fire hazards of the PS composites.