Flame‐Retardant and Flexural Properties of Polypropylene/Intumescent Composites

The flame-retardant and flexural mechanical properties for the polypropylene (PP) composites filled with intumescent flame retardant (IFR) were measured. It was found that the limited oxygen index increased roughly linearly, whereas the horizontal combustibility rate decreased with increasing theIFR weight fraction; when the IFR weight fraction was more than 10%, the smoke density rank decreased with increasing the IFR weight fraction; the flexural modulus and the flexural strength increased when IFR weight fraction was lower than 20% and then decreased with increasing the IFR weight fraction; the values of the flexural modulus and the flexural strength reached to the maximum at the IFR weight fraction of 10%. Moreover, the flexural modulus and the flexural strength of the composites were higher than that of the unfilled PP resin.