Abstract: An intumescent flame retardant (IFR) was prepared by mixing a hyperbranched triazine charring agent with ammonium polyphosphate at a mass ratio of 1∶1 and then used for the flame retardancy of polypropylene (PP). The mechanical and flame-retardant properties of the resulting flame-retardant PP are evaluated by means of impact and tensile measurements, LOI test and vertical burning experiment, and the cross-section morphology was observed by SEM. The characterization results indicated that the impact strength of flame-retardant PP increased first and then tended to decrease with an increase of IFR content. However, the tensile strength exhibited a continual decrease with increasing the content of IFR. The flame-retardant PP containing 15 % IFR achieved a UL 94 V-0 classification, implying an excellent flame retardant effect.

Key words: flame retardant, charring agent, polypropylene, mechanical property