The high efficiency two stage intumescent-contractive flame retardant on ABS

One stage halogen-free flame retardant was prepared by poly(p-ethylene terephthalamide) (PETA) or poly(para-phenylene terephthanlamide) (PPTA) and ammonium polyphosphate (APP), the system had a good flame retardancy on acrylonitrile-butadiene-styrene (ABS) resin when loading was 30% or more, but once mass fraction decreased, the system did not maintain previous flame retardancy. To improve the efficiency of this kind of flame retardant, we mixed PETA with PPTA and introduced red phosphorus to play as the second acid source. This system had two charring process-swell and shrink. The flammability and thermal stability of IFR-ABS composites were investigated by limiting oxygen index (LOI), UL-94 vertical burning and thermo gravimetric analysis (TGA) test. Results showed that this IFR system had both good flame retardant and anti-dripping abilities for ABS, when the mass fractions of APP, PETA, PPTA and red phosphorus were only 12%, 4%, 1.33% and 2.66% respectively, the LOI of flame retardant ABS was 27 and UL-94 vertical burning test reached V-0. The TGA curves suggested that there was a distinct cooperation. Additionally, the structure and the mechanism of charring were studied by FTIR and SEM.