Covalent flame-retardant functionalization of wool fabric using ammonium phytate with improved washing durability

The exploitation of resourceful plant derivatives for fabricating durable flame retardant (FR) textiles is of great interest. Herein, this study offers a novel and facile approach for developing FR wool fabric by covalently grafting bio-based ammonium phytate (APH) onto wool fibers. The potential grafting action of APH with wool fibers, the flame retardancy and washing durability, smoke and heat emission performance and FR mechanism of modified wool fabrics were explored. The modified wool fabrics could pass the vertical burning B1 classification with a reduced char length of approximately 10.0 cm from 30.0 cm, and they also had an increased LOI of approximately 32.0% from 23.6%. The modified wool fabrics possessed increased tensile strength; they also selfextinguished during the vertical burning test after 15 washing cycles, which was attributed to the crosslinking action of APH with wool fibers. Besides, a significant reduction in smoke and heat release of wool fabric was achieved after FR grafting. The investigations on char residue confirmed the intumescent FR mechanism for APH modified wool fabrics. In general, the present study provides an industrial feasible strategy to prepare sustainable and durable FR wool fabrics using phytate derivatives.