Abstract: An organic silicon-containing charring agents (CA) was synthesized from cyanuryl chloride，3-Triethoxysilylpropylamine, and p-phenylenediamine, which was introduced into polypropylene (PP) together with ammonium polyphosphate (APP) as an intumescent flame retardant (IFR). The effect of APP/CA on flame retardancy, mechanical properties, and thermal stability of PP was investigated. It showed that APP/CA had excellent flame retardancy in PP. CA had a good function in char formation. The organic silicon group could accelerate charring performance of PP, made the structure of char layer continuous and compact. The addition of APP/CA improved the thermal stability of PP, effectively restrained the further burning of PP. When the weight ratio of APP/CA was 3/1, and the loading was 28% in PP, the LOI value of APP/CA /PP reached 32.5 and passed UL94V-0 grade.

Key words: polypropylene, triazine charring agent, organic silicon, flame retardant