Abstract: An intumescent flame retardant system formulated with a phosphorussilicon compound (EMPZR), ammonium polyphosphate (APP), and melamine polyphosphate (MPP) was introduced into polypropylene (PP) via blending. When the mass ratio of APP/MPP/EMPZR was 15/10/15, the limited oxygen index of the composites was increased to 33 %, and the burning grading reached UL94 V0. The tensile, bending, and impact strengths of the composites were no less than plain polypropylene. Thermogravimetry analysis up to 600 ℃ showed that the char residue of the composites was 21.14 % which indicated a good synergistic effects of EMPZR with APP and MPP.

Key words: polypropylene, phosphorus-silicon flame retardant, ammonium polyphosphate, melamine polyphosphate, flame retardancy