Mechanisms and effects of sunlight exposure on disperse-dyed aromatic polysulfonamide fibers

This study explores the sunlight resistance of polysulfonamide (PSA) fabrics dyed with dispersed dyes through a high-temperature, high-pressure carrier dyeing method. PSA fibers, valued for their thermal stability and chemical resistance, exhibit low light fastness under ultraviolet (UV) exposure. The UV absorption, color fastness, and degradation of PSA fabrics dyed with Disperse Red 60 (DR), Disperse Blue 56 (DB), and Disperse Violet 26 (DV) were analyzed. UV–visible spectroscopy showed that PSA/DB had the highest UV absorption and photostability, followed by PSA/DV and PSA/DR. The electron spin resonance analysis confirmed a higher concentration of free radicals in PSA/DB, indicating enhanced UV absorption. Although UV protection improved, light fastness across all dyed PSA fabrics remained low, with notable photofading in sunlight-exposed samples. Mechanical tests and scanning electron microscopy revealed that PSA/DB displayed better resistance to UV-induced degradation, maintaining greater strength and showing less surface damage compared with PSA/DR and PSA/DV. X-ray photoelectron spectroscopy showed that disperse dyes helped mitigate amide bond degradation in PSA fibers. This study highlights the importance of dye selection in improving UV resistance and durability for PSA fabrics in applications requiring prolonged sun exposure.