N‐methylmorpholine‐N‐oxide molecules coated ammonium polyphosphates for dope spinning of flame‐retardant lyocell fiber

Abstract Lyocell fiber, hailed as the “verdant filament of the 21st century,” boasts elevated tensile strength, environmentally conscientious production practices, and innate biodegradability. Nonetheless, its intrinsic combustibility constitutes a noteworthy impediment to its pervasive utilization across textile and industrial domains. In a concerted effort to surmount this challenge, ammonium polyphosphate (APP) underwent modification through the infusion of N ‐methylmorpholine‐ N ‐oxide (NMMO) molecules, amplifying its dispersibility within lyocell solutions. The resultant NMMO‐coated ammonium polyphosphate (NAPP) underwent meticulous characterization of both its structure and properties. Remarkably, lyocell fiber impregnated with 30% NAPP exhibited exemplary flame retardancy, enduring through 30 laundering cycles. Notably, its tensile strength remained notably robust at 139 MPa, demonstrating a mere 6.1% reduction in comparison to its pristine lyocell counterpart. This study delineates a promising trajectory for the fabrication of mechanically resilient lyocell fibers endowed with commendable flame‐retardant attributes. Highlights The raw material is waste cotton textiles, prepared on a green basis. The use of ultrasonic mixing and low‐speed stirring defoaming method and the use of room temperature spinning advantage of the production of flame retardant lyocell fiber. The amount of flame retardant is small, and the mechanical strength is reduced to a lesser extent. Good flame‐retardant effect and excellent water washing resistance.