Eco-friendly flame-retardant polyamide 6 fabrics with balanced flame retardant and mechanical strength via composite synergies

Eco-friendly flame-retardant fabrics have recently been widely concerned and developed due to highly flammable characteristics of fabrics and environmental protection issues. Phytic acid (PA) was optimized as a common flame-retardant relying on its environmentally friendly and flame retardant characteristics. However, the strong acidity of PA always results in the loss in mechanical properties of the fabric. Herein, a synergetic strategy by compositing PA and ethanolamine (ETA) was proposed to enhance the flame resistance of the PA6 fabric. As a result, after the flame-retardant coatings prepared by the synergy of PA and ETA are impregnated on the surface of PA6 fabric, the limiting oxygen index (LOI) of PA6 fabrics increased from 21.2 % to 30.4 % with on a well mechanical strength retention rate (MSR) (more than 75 %), which is much better than the PA6 fabric treated by pure PA (LOI: 25.3 %, MSR: less than 40 %). The analysis results indicate that ETA not only reduces the damage of PA to PA6 fabrics but also plays an important role as a carbon and nitrogen source in the intumescent flame-retardant mechanism. This synergistic strategy provides a new reference for the development of environmentally friendly flame-retardant coatings. • A flame retardant coating was synthesized from phytic acid and ethanolamine. • The PE-PA6 fabric is assembled from PA6 fabric and a flame retardant coating via hydrogen bonding. • PE-PA6 fabrics exhibit excellent flame retardant properties and tensile strength. • The flame retardant mechanism of PE-PA6 fabrics is a combination of the condensed-phase and gas-phase.