High efficiency of flame-retardant polyamide 56/10-(2, 5-dihydroxyphenyl)-10-hydrogen 9-oxygen-10-phosphine-10-oxide composites inspired by polyoxometalate

Polyamide 56 (PA56) as a bio-based polymer has some flame retardancy but is not good enough to satisfy the security requirements. In this communication, nickel phosphomolybdate (PMoNi) was synthesized and applied to modify the fire-retardant efficiency of 10-(2,5-dihydroxyphenyl)-10-hydrogen 9-oxygen-10-phosphine-10-oxide (DOPO-HQ) in PA56. An efficient synergistic effect is found between DOPO-HQ and PMoNi. The content of DOPO-HQ in PA56 to achieve the UL-94 V-0 rating is decreased from 15 wt% to 3 wt% by incorporating 1 wt% PMoNi into the system. It inspires the condensed-gas transition of phosphorus in DOPO-HQ and improves the fire-retardant efficiency by enhancing gas-phase effect. This work provides an effective method for preparing fire-retardant PA56 composites.