Facile preparation of effective flame retardant silk fabric by the metal salt adsorption approach

In this study, flame retardant (FR) functional silk fabric was prepared by the facile adsorption of metal salts (ferrous, aluminum and titanium sulfate) at low concentration. This study tried to provide a good understanding on the FR ability and action of metal salts on silk fabric. The morphological structure and functional groups of silk fiber before and after treatment were studied. The thermal stability, smoke generation ability and FR ability of the treated silk were evaluated. The iron, aluminum and titanium salts endowed silk fabric with self-extinction effect at a concentration of 0.1, 0.5 and 1.0 g/L, respectively. The metal salts also showed good washing resistance on silk fabric; for example, the aluminum salt treated silk still reached self-extinction after 10 robust washings, which is attributed to the complexation capacity of silk macromolecule with metal ions. The thermal stability and char residues analyses suggested the condensed phase FR mechanism for the treated silk, and the good ability to promote char formation contributed to their FR functionality. This study suggests that certain metal salts are effective enough to serve as suitable alternative to toxic halogen-based chemicals for enhancing fire safety of silk textiles. (C) 2020 Elsevier Ltd. All rights reserved.