Abstract: In this work, a flame retardant system containing P-N intumescent flame retardant (melamine phosphate, IFR), ammonium polyphosphate (APP), and polytetrafluoroethylene (PTFE) was applied in polypropylene (PP). The burning property of the IFR/APP/PTFE system flame retarded PP was tested by limited oxygen index and UL 94 measurement. Using thermogravimetric, Fourier transform infrared spectroscopy, scanning elecreon microscope, and X-ray photoelectron spectroscopy, the burning property, thermal degradation process, and the components of residual carbon of flame retarded PP were analyzed, and the flame retardancy mechanism of PP/IFR/APP/PTFE system was studied. It showed that the IFR/APP/PTFE flame retardant system showed significant synergistic effect, and the PP/IFR/APP/PTFE could reach a limited oxygen index value of 30.1 % and UL 94 V-0 with only 24 % IFR/APP/PTFE flame retardant (APP 6 %, IFR17.5 %, PTFE 0.5 %). In addition, the thermal stability of PP was improved by the introduction of the flame retardant.

Key words: polypropylene, P-N intumescent flame retardant, flame retardant mechanism