Flame-retardant treatment of silk fabric with sodium phytate and chitosan using the layer-by-layer padding technique

Bio-based flame-retardant agents and layer-by-layer assembly have attracted a great deal of attention in the flame-retardant fields of textiles, composites and polymeric materials. In this study, the electrostatic layer-by-layer assembly of chitosan and sodium phytate on silk fabric was carried out using a padding technique. The effects of the concentration and assembled bilayer of chitosan and sodium phytate on the weight gain, flammability, surface morphology, whiteness, stiff ness, lustre, tensile strength, and washing durability of silk fabric were studied, and the heat release, thermal stability and flame-retardant mechanism of the coated fabric were analysed. The results revealed that at 10 to 15 assembled bilayers, the coated fabrics exhibited high limiting oxygen indexes and passed the vertical burning test, and their good flame retardancy was maintained even after 15 washing cycles. Moreover, the coated fabrics exhibited a significant decrease in peak the heat release rate and a strong charring ability at high temperatures. The chitosan and sodium phytate system acted as flame retardants in the condensed phase. Given the high weight gain of silk fabric, the layer-by-layer assembly of chitosan and sodium phytate using a padding technique was more applicable to the flame-retardant treatment of furnishing fabrics.