Synergistic effect of a novel charring agent with ammonium polyphosphate on flame retardancy and thermal degradation of acrylonitrile‐butadiene‐styrene copolymer

A novel charring agent poly(1,3‐propylene terephthalamide) (PPTA) was synthesized and characterized by Fourier transform infrared spectroscopy and ¹H nuclear magnetic resonance. This novel charring agent combined with ammonium polyphosphate (APP) was adopted as an intumescent flame retardant (IFR) to impart flame retardance and dripping resistance to acrylonitrile‐butadiene‐styrene copolymer (ABS). Flammability and thermal behaviors of the treated ABS were investigated by limiting oxygen index, vertical burning test and thermogravimetric analysis. The results showed that the IFR with the novel charring agent had both excellent flame retardant and anti‐dripping abilities for ABS. The thermogravimetric analysis curves indicated that there was a synergistic effect between PPTA and APP, which greatly promoted the char formation of IFR‐ABS composites. Meanwhile, the thermal degradation mechanism of PPTA and APP/PPTA was characterized using thermogravimetric analysis/infrared spectrometry. The results demonstrated that APP changed the thermal degradation behavior of PPTA and reacted with PPTA to form a crosslinked structure. Additionally, the structure and morphology of char residues were studied by Fourier transform infrared spectroscopy and scanning electron microscopy. Copyright © 2011 Society of Chemical Industry