Water-based chitosan / melamine polyphosphate multilayer nanocoating that extinguishes fire on polyester-cotton fabric

Polyester-cotton (PECO) blends are widely used in the textile industry because they combine the softness of cotton and the strength and durability of polyester. Unfortunately, both fiber types share the disadvantage of being flammable. The layer-by-layer coating technique was used to deposit a highly effective flame retardant (melamine polyphosphate) from water onto polyester-cotton fabric. Soluble melamine and sodium hexametaphosphate form this water-insoluble flame retardant during the coating procedure. This unique nanocoating imparts self-extinguishing properties to PECO with only 12% relative coating weight. Vertical flame testing, pyrolysis combustion flow calorimetry (PCFC), thermogravimetric analysis (TGA), and scanning electron microscopy were used to evaluate the quality of the coating as well as its flame retardant performance. A combination of both condensed and gas-phase activity appears to be the reason for this effective flame retardancy. Degradation pathways of both cotton and polyester are affected by the applied coating, as shown by PCFC and TGA. Use of environmentally benign and non-toxic chemicals, and the ease of layer-by-layer deposition, making this coating an industrially feasible alternative to render polyester-cotton fabric self-extinguishing.