Phytic acid as a bio-based phosphorus flame retardant for poly(lactic acid) nonwoven fabric

Bio-based phytic acid as a nontoxic naturally occurring compound has a promising prospect in the field of the flame retardant modification of polymers because of its high phosphorus content. Bio-based and bio-degradable poly(lactic acid) has aroused considerable interest and its use is growing, but its flame retardancy needs to be improved when it is used as a flame retardant material. In this work, phytic acid was used to improve the flame retardancy of poly(lactic acid) nonwoven fabric by a pad-dry-cure technique, and the effect of phytic acid dosage on the flammability as well as the flame retardant mechanism of the treated fabric was discussed. The limiting oxygen index and vertical burning tests revealed that the treated fabric exhibited good flame retardancy. The microscale combustion calorimetry analysis showed that the treated fabric had significantly decreased heat release rate, total heat release and heat release capacity compared with the untreated fabric. The char residue formation of the treated fabric during thermal degradation, and the high phosphorus content of the burned fabric residue suggested that a significant condensed-phase mechanism contributed to the flame retardancy of the treated fabric. The flame retardant system in the present study is applicable to the poly(lactic acid) fabrics without the durability requirement. The use of phytic acid provides an opportunity for producing the flame retardant poly(lactic acid) materials using a sustainable and cleaner flame retardant agent.