Chemically modified wool waste keratin for flame retardant cotton finishing

Abstract

Environmentally friendly flame retardant chemicals are being developed in recent studies as legislation for eco-sustainable textile production becomes more stringent around the world. Utilisation of waste generated by the wool spinning industry is a prime concern with present work. The extraction and modification of keratin from waste wool for flame retardant cotton has not been attempted previously. The research describes a unique method for using chemically modified keratin derived from wool waste as an environmentally acceptable nitrogen/phosphorus containing flame retardant for cotton fabrics. Melamine and sodium pyrophosphate were used as nitrogen and phosphorus sources, respectively, along with glyoxal as a cross-linking agent. The improved thermal stability of modified wool waste keratin and treated cotton fabrics was confirmed by TGA, while structural changes were established by FTIR and XRD analyses. Due to the synergistic impact of nitrogen and phosphorous, the modified wool waste keratin resulted in the formation of a continuous and intact layer of char that confers flame retardancy on treated cotton. The limiting oxygen index of cotton after application of the modified keratin showed a nearly 66.7% increase in flame retardancy compared to untreated cotton. Overall, the findings in the paper show a sustainable approach for the textile industry that combines waste utilisation from one textile sector (minimizing solid waste from the wool industry) with waste management elements to add value to another (multifunctional textile finishing agent for the cotton industry).