Environmentally friendly pre‐treatments for sustainable coloration: Enhancing natural dyeing of polyester fabric via ultraviolet rays and ozone modification

Abstract The hydrophobic nature of polyester fibres and their low moisture regain limit their dyeing process with natural colorants. Therefore, to enhance the surface wettability of the fabrics and improve dye affinity, surface modification pre‐treatments using ultraviolet (UV), ozone (O 3 ) and a combination of UV/O 3 were applied. The chemical and morphological changes in the fabrics were evaluated using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) analyses, respectively. All samples were dyed with madder as a common natural dye. Post‐dyeing performance tests, such as colour strength, tensile strength, water vapour permeability, air permeability and overall moisture management capacity (OMMC), were conducted on the samples. The results demonstrated that both UV and O 3 treatments significantly improved the dyeability of the fabrics and their moisture management properties. The highest colour strength value for O 3 ‐treated samples was obtained with a gas flow rate of 15 L/min and an ozonation time of 90 min, while for UV treatment, the highest colour strength was achieved at a lamp distance of 21 cm with an irradiation time of 120 min. In the combined treatment trials, the highest colour strength value was achieved with UV, followed by O 3 treatment; however, mechanical strength was further reduced. FTIR analysis confirmed the formation of new functional groups, and SEM images revealed surface etching and an increase in roughness. These findings reveal the potential of these environmentally friendly physical modification methods to enhance the dyeability of polyester fabrics with natural dyes.