Preparation and investigation of efficient flame retardant TPE composites with piperazine pyrophosphate/aluminum diethylphosphinate system

The piperazine pyrophosphate (PPAP) combined with aluminum diethylphosphinate (AlPi) with a certain mass fraction and then incorporated into thermoplastic elastomer (TPE) composites composed of oil extended styrene-ethylene-butadiene-styrene block copolymer and polypropylene. The fire retardancy, thermal behavior, mechanical performance, and flame retardant mechanism of TPE materials were investigated in detail. The results demonstrated that 1.6 mm TPE composites reached UL-94 V-0 grade during vertical burning tests and the limiting oxygen index value was 28.5% when 25 wt % PPAP/AlPi with the mass ratio of 4:1 was incorporated. The introduction of PPAP/AlPi improved the residual mass and thermal stability, and stimulated to produce the char layer with high quality. The formed char layer exerted shielding effect and AlPi could inhibit the flame in gas phase. Consequently, the PPAP/AlPi system evoked fire retardant effects in condensed and gas phase simultaneously, and the fire resistance of the TPE composites was enhanced. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 47711.