High efficiency intumescent flame retardancy between Hexakis (4-nitrophenoxy) cyclotriphosphazene and ammonium polyphosphate on ABS

Hexakis(4-nitrophenoxy) cyclotriphosphazene (HNTP) with ammonium polyphosphate (APP) were added to acrylonitrile-butadiene-styrene copolymer (ABS) to improve the intumescent flammability and thermal properties of ABS. The effect of intumescent flame retardancy was characterized by limited oxygen index (LOI), vertical burning test (UL-94), thermos gravimetric analysis (TGA) tests, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). When the loading of ABS, HNTP and APP were 70, 15 and 15%, respectively, the LOI value reached 25.6 and UL-94 test was V-0. The TGA showed the high char yield of ABS/30%HNTP system at high temperatures. The experimental and theoretical TG curves and FTIR indicated that HNTP and APP promoted the form of cross-link structure, which acted as a barrier near the surface of material. The SEM further revealed the formation morphology of intumescent charred layer on ABS/15%HNTP/15%APP system. Tensile tests provided the possibility of using HNTP at high temperature.