Abstract: In order to improve the flame retardancy of polyoxymethylene (POM), the flame retardant POM composites were prepared by melt blending ammonium polyphosphate (APP) - diammonium hydrogen phosphate (DAP)-corn starch (CS) with POM. The samples were tested and characterized by limiting oxygen index (LOI), horizontal vertical combustion (UL-94), thermogravimetry differential scanning calorimetry (TG-DSC), scanning electron microscopy (SEM) and cone calorimeter (CONE). The results show that the LOI of flame retardant POM can reach 38 when APP: DAP: CS = 4:3:1, UL-94 grade is V-1.The heat release rate and total heat release are relatively small.The structure of carbon layer is compact and stable, which indicates that APP-DAP-CS intumescent flame retardant system can effectively inhibit the combustion of POM and has a good flame retardant effect.

Key words: polyoxymethylene, intumescent flame retardant, APP, CS, DAP