Sustainable flame retardancy of cotton fabric using eucalyptus wood extract

Cotton fabrics, composed primarily of cellulose, are highly flammable and contribute significantly to fire-related accidents. This study focuses on improving the flame-retardant properties of cotton fabrics through the application of crude lignin, a natural macromolecule extracted from eucalyptus wood chips. A refined alkaline pulping process was employed to isolate crude lignin from eucalyptus wood, with optimal extraction conditions determined using central composite design Expert software. The optimum parameters for lignin extraction were identified as a 20% NaOH concentration, a temperature of 100 °C, and an extraction duration of 4 h, yielding a maximum extraction yield of 68%. Surfactants were added to the black liquor solution, and acetic acid was used to precipitate the extracted crude lignin. The crude lignin solution was then applied to cotton fabric using the pad-dry-cure method, achieving a maximum add-on rate of 31.5%. The flame resistance of the treated cotton fabrics was evaluated according to the ASTM D6413 test standard. Results demonstrated a significant reduction in char length and width, along with improved flame resistance. This study provides a strong foundation for the commercial development of sustainable flame-retardant treatments for cellulose-based textiles.