Flame retardant polyester fabric from nitrogen-rich low molecular weight additives within intumescent nanocoating
An intumescent nanocoating composed of chitosan (CH) and ammonium polyphosphate (APP), with and without low-molecular weight nitrogen and nitrogen/sulphur based derivatives, was deposited on polyester fabric using the layer-by-layer technique. Guanidine sulfamate (GSM), urea and thiourea were added to the aqueous chitosan deposition solution in an effort to improve flame retardancy. Exceptional self-extinguishing behavior is observed with a 10 bilayer (BL) CH:GSM/APP coated fabric. This water-based coating added 19.6 wt% to the polyester and reduced peak heat release rate by 61.7%, relative to uncoated fabric. Furthermore, the polyester is not fully ignitable because of earlier decomposition of GSM that helps to generate a thicker sponge-like char that acts as a physical barrier. This unique addition of low-molecular weight molecules in traditional intumescent polyelectrolyte pairs is a new opportunity for imparting flame retardancy to highly flammable synthetic fibers used in clothing and home furnishing.
I. Jordanov, E. Magovac, A. Fahimi, S. Lazar, T. Kolibaba, R.J. Smith, S. Bischoff, J.C. Grunlan, Polym. Degrad. Stab., 2019, 170, 108998.