Preparation and mechanism of phosphoramidate-based sol-gel coating for flame-retardant viscose fabric

To prepare efficiently flame-retardant sol-gel coating for viscose fabric, a novel phosphoramidate siloxane (TSPDP) was synthesized and fire-safety viscose fabrics were prepared via sol-gel method with different contents of TSPDP. When the weight gain (WG) was more than 13%, higher limiting oxygen index (LOI) value was obtained and the coated viscose fabric passed the vertical flammability test with self-extinguishing behavior. A sharp reduction of more than 42% in peak of heat release rate (pHRR) was discovered for coated viscose fabric in contrast with pure sample. The good flame retardancy of TSPDP-coated viscose fabric was due to the co-presence of P, N and Si elements, which can form a char layer barrier in condensed phase during the combustion and inhibit the release of flammable volatiles in high temperature. Moreover, this coating had few effects on the tensile strength of viscose fabric. (C) 2021 Elsevier Ltd. All rights reserved.