Enhanced Flame Retardancy and Mechanical Properties of Intumescent Flame-Retardant Polypropylene with Triazine Derivative-Modified Nano-SiO₂

Nano-silica was modified with triazine derivative and characterized using FTIR and TGA techniques. Then the hybrid nano-silica was blended with polypropylene and intumescent flame retardant to prepare a novel intumescent flame-retardant polypropylene. Nitrogen and phosphorus elemental mapping micrographs and SEM micrographs elucidated that the hybrid nano-silica could facilitate intumescent flame retardant to disperse more uniformly in polypropylene. TGA results showed that hybrid nano-silica could improve the thermal stability of polypropylene. With 18% intumescent flame retardant and 2% hybrid nano-silica, the novel intumescent flame-retardant polypropylene got a limiting oxygen index of 29.7% and passed the vertical burning (UL-94) V-0 rating. Cone calorimeter test showed that the peak heat release rate and total heat release clearly decreased.