The synergistic effects of a novel intumescent flame-retardant poly-(4-nitrophenoxy)-phosphazene and ammonium polyphosphate on ABS systems

Novel intumescent flame retardancy acrylonitrile-butadiene-styrene (ABS) composites were prepared by adding poly-(4-nitrophenoxy)-phosphazene (DPP) as charring and inflate agent, and ammonium polyphosphate (APP) as acid and inflate agent. The flame-retardant properties of samples were studied by LOI, UL-94 and microscale combustion calorimeter (MCC), when the ratio of APP and DPP was 1:1 with 30mass% additive amount, the LOI was 27%, and the UL-94 reached V-0 rating. To further study the synergistic effects of DPP and APP, the charring-forming capability and thermal behavior of ABS composites were extensively studied by thermogravimetric analysis (TGA) under nitrogen and air, respectively. Also the binary system of APP and DPP was investigated by TGA measurements to identify their reaction and the synergistic mechanisms. The char residues were studied by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) analysis and Fourier transform infrared (FTIR). Meanwhile, the gaseous products generated in degradation process were detected by thermogravimetric analysis coupled Fourier transform infrared (TGA/FTIR).