Graphene oxide (GO) was prepared via Hummers' method

and its micromorphology was detected by scanning electron microscopy (SEM) and atomic force microscopy (AFM).The synergetic effects of GO and Si-P oligomer (DMS-DOPO) on flame retardant and mechanical properties of EP were studied in detail.Universal testing results showed that GO and DMS-DOPO had good effect on tensile strength and elongation at break

respectively.Tensile strength and elongation at break of EP were enhanced by 17.1% and 42.2% synergistically effected by GO and DMS-DOPO.Thermal and flame properties of EP and its composites were measured through thermal gravimetric analysis (TG)

limiting oxygen index (LOI)

vertical burning test (UL-94) and cone calorimeter (CONE).The micromorphology of char residual was observed by SEM.The char residual amount of EP/DMS-DOPO/GO was 5.2 times that of EP at 600 ℃

and 4.4% higher than that of EP/DMS-DOPO

208% for EP/GO.EP/DMS-DOPO/GO could pass UL-94 V-0 level

and its LOI value was over 30.Intumescent char layer with polyphorous inner structure and compact outside surface was formed during the combustion of EP/DMS-DOPO/GO.The heat release rate (HRR) of EP reduced from 1154 kW m-2 to 710 kW m-2 due to synergistical flame retard and effect of DMS-DOPO and GO.Total smoke production (TSP) of EP/DMS-DOPO/GO was 30% lower than that of EP.