Bio-based alginate and Si-, P- and N-containing compounds cooperate toward flame-retardant modification of polyester fabrics

Imparting flame retardancy to polyester fabrics is still a pressing issue for the textile industry. To this end, a composite coating was developed by phosphite, pentamethyldisiloxane, urea and sodium alginate, and then applied together with calcium chloride to prepare flame-retardant polyester fabrics. The optimized polyester fabrics named PF-HUSC exhibited a rough surface with P, Si, N and Ca element distributions, as observed by scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDX). Flame retardancy evaluations showed that the damaged length of PF-HUSC with a limiting oxygen index (LOI) value of 35.3 ± 0.3 % was reduced from the contrastive 17.6 ± 0.4 cm to 4.6 ± 0.2 cm after vertical burning test. Thermogravimetric (TG) test confirmed that PF-HUSC retained a char residue as high as 35.1 % at 700 °C. Cone calorimetry test displayed that the total heat release (THR) and total smoke production (TSP) values of PF-HUSC were reduced to 3.1 MJ/m2 and 1.1 m2, respectively, as compared to those of pure polyester fabrics. More importantly, PF-HUSC still exhibited higher LOI value than that of pure polyester fabrics after 25 washing cycles. Hence, the coating scheme is considered as a new method to expand the preparation of flame-retardant polyester fabrics.