The influencing mechanism of thermo-oxidative aging of waste cotton textiles on mechanical properties of their regenerated fibers

Recycling and reuse of waste cotton textiles reduces environmental pollution and lowers energy consumption. Currently, researchers have conducted a lot of studies on the reuse of waste cotton textiles, but there are fewer studies on how the degree of their aging affects the properties of the regenerated fibers. In particular, the higher the degree of aging, the greater the change of physical and chemical properties of them, thus limiting their reuse value. In this paper, ionic liquids were used to dissolve cotton textiles with different degree of aging, and the effect of aging degree of cotton textiles on the viscosity of spinning solution was investigated by measuring the rheological behavior of spinning solution. The regenerated fibers were prepared by wet spinning and the mechanical and chemical properties of the regenerated fibers were characterized. When comparing regenerated fibers made from cotton textiles that have not been aged with those made from cotton textiles aged at 200°C, the tensile strength of the regenerated fibers decreases from 204.83 MPa to 47.5 MPa, and the hydroxyl vibration peaks of the regenerated fibers are weakened. With the help of molecular dynamics simulation, the aging process of cotton textiles under different temperature conditions was explored, at high temperatures, cellulose molecular chains break and intramolecular hydrogen bonding is reduced, resulting in reduced mechanical properties. Therefore, the selection of waste cotton textiles with the appropriate degree of aging according to the recycling purpose can help to realize the efficient use of waste textiles.