Abstract: The effect of two intumescent flame retardants, ammonium polyphosphate (AP) and phosphate ester (NP), on the mechanical properties, flammability, and anti-water-blooming properties of PP/SBS/POE blends was studied. The kinetics of the retardants blooming was also analyzed. It showed that NP exhibited a higher thermal decomposition temperature and more char residue than AP. As the retardants increased, mechanical properties of the blends decreased but their flame retardancy were improved. At the same loading amount, the blends with NP showed the higher tensile strength and limited oxygen index. AP inversely promoted the charring of polymer matrix. Part of AP and NP moved outside from inside after the blends were soaked in heated water. The blooming is a processing that extends from the surface to inside of the samples. The amount of blooming increased with the soaking time. NP showed the lower amount of blooming at the same soaking time. As to the soaked blends, tensile strength and flame resistance were deteriorated.

Key words: polypropylene, styrene-butadiene-styrene block copolymer, ethylene-octene copolymer, intumescent flame retardant