A bio-based flame retardant coating used for polyamide 66 fabric

Phytic acid (IP6) is the principal storage form of phosphorus in many plant tissues, especially the bran portion of grains and other seeds. This paper describes an attempt to develop a bio-based finishing using IP6 biomolecules in order to reduce the flammability of polyamide 66 (PA 66) fabric and solve its melt dripping problem. ATIR-FTIR and SEM characterizations indicate the formation of a bio-based coating containing POP groups (O-IP6 bio-oligomer) by hydration reaction between IP6 biomolecules during finishing. The limiting oxygen index test and the vertical burning test show that the treated PA fabric has the highest LOI value of 32.3 and self-extinguishing behavior without melt dripping, confirming the ability of O-IP6 coating to improve the fire performance of thermoplastic polyamide fabric. And enhancement in char formation of the treated fabric and reduction in its total heat release have also been verified by thermogravimetry analysis and microcalorimetry. Durability test reveals O-IP6 oligomeric structure could promote the water resistance of the treated sample, which could keep 82.7 % of the original LOI for 25IP6-PA fabric after 20 times washing with water alone. Moreover, the interesting intumescent-like flame retardant mechanism of IP6-PA fabric has also been proposed here.