In order to improve the flame retardant efficiency of APP-PETA，APP-PA6T and APP-PPTA system on acrylonitrile-butadiene-styrene (ABS) resin ,red phosphorus was introduced to play as the second acid source. The effect and FTIR spectrum of flame retardant residue of these systems were analyzed,and PETA and PPTA were chosen as char agent,APP and red phosphorus as acid source to form the flame retardant.When the mass fraction of two-stage flame retardant was 30%,theLOIof flame retardant ABS was 34 and UL-94 vertical burning test reached V-0,even when the loading decreased to 20%,theLOIvalues still has 27 and past the V-0 test.FTIR spectrum of two-stage flame retardant residue suggested that there was a distinct cooperation which prolong the working time. The macroscopical structure of char layer showed this flame retardant had two work processes,swollen and shrunk,the second process made char layer more compact,The ABS composites SEM photograph after completely combustion showed that two-stage flame retardant would form compact char layer when mass fraction was 30% or 20%,and this endow ABS good flame retardancy.
