Scalable preparation of cottonseed meal-based flame retardants via mechanical grinding for surface modification of cotton fibers

The research progress on the surface modification and flame retardancy of cotton fibers has been rapid. Driven by considerations of environmental safety and economic feasibility, bio-based flame retardants are favored for their eco-friendly and sustainable characteristics. This study successfully scaled up the preparation of a P/N-rich cottonseed meal-based flame retardant (PmC) − a functional material in which phosphate groups are chemically introduced into the natural components of cottonseed meal. The innovative mechanical grinding method refines solid biomass for application on the surface of cotton fibers. PmC integrates with cotton fibers through a flame-retardant finishing process, forming hydrogen bonds and covalent bonds between PmC and cotton fibers, thereby achieving durable wash resistance for flame-retardant cotton fibers. The limiting oxygen index (LOI) of 110 g/L PmC treated cotton fibers reaches 38.4 %, with a damage length of only 50 mm. Cone calorimetry tests revealed that the total heat release (THR) and peak heat release rate (pHRR) of PmC-treated cotton fibers were reduced by 38.7 % and 82.9 %, respectively. Comprehensive analysis using TG-IR, XPS of the residual char, SEM-EDS further indicated that PmC primarily exerts its flame-retardant effect by acting on the condensed phase of cotton fabrics.