Dyeing polyester fibres with disperse dyes typically involves high process temperatures exceeding 130°C, necessitating pressurized dyeing machines. Given the high amount of polyester fibre consumption in the textile industry an‎d the substantial water consumption during their dyeing, developing an alternative method that reduces water usage while enabling atmospheric-pressure dyeing is highly desirable. The present research explores the application of ionic liquids for dyeing polyester fibres. Ionic liquids (ILs), salts with low vapour pressure, have recently been used as dyeing mediums. Protic ionic liquids, a subclass of these solvents, are desirable due to their relatively lower-cost raw materials an‎d simpler synthesis processes. In the present study, a protic ionic liquid based on monoethanolamine an‎d acetic acid was synthesized for the application as a medium in polyester fibre dyeing with disperse dyes. The ionic liquid, identified as N-(2-hydroxyethyl)acetamide with a molar ratio of 1:1.5 monoethanolamine to acetic acid, was characterized using FTIR, C NMR, an‎d H NMR spectroscopy. The EDS analysis indicated the retention of nitrogen groups from the solvent on the fibres even after ethanol washing. This retention was related to hydrogen bonding between the ionic liquid an‎d the polyester fibre surface. The synthesized ionic liquid exhibited high viscosity, which decreased with increasing temperature, ensuring its suitability as a dyeing medium. Karl Fischer titration determined the water content of the synthesized ionic liquid to be 1.1%, which was considered acceptable. XRD analysis showed a subtle reduction in polyester fibre crystallinity with increasing dyeing temperature in the ionic liquid. Martindale abrasion test demonstrated no adverse effects of the ionic liquid on polyester fibre’s abrasion resistance. Hydro‎philicity tests indicated enhanced moisture adsorption on the fibre surface, attributed to the hydro‎philic functional groups of the IL an‎d a slight increase in amorphous regions resulting from high-temperature treatment in the IL. Dyeing of the fibres was conducted to investigate the effect of temperature an‎d L:R on the kinetics an‎d thermodynamics of dyeing the fibre with disperse dyes in the synthesized IL. The optimal dyeing conditions were obtained an‎d the results compared with the dyeing of the fibres in conventional dyeing using water. The results showed the dyeing rate an‎d dye exhaustion in IL (with no dispersing agent) is less than conventional dyeing in water. The wet an‎d dry rubbing an‎d wash fastness of the fabrics dyed in IL an‎d water were similar an‎d excellent. Also, it was shown that the tensile strength in both dyeing liquids was comparable. Thermodynamic parameters indicate the adsorption of dyes on the fibre for dyeing in IL was an exothermic process, with less adsorption tendency of the dyes on the polyester fibre after dyeing with IL, an‎d higher adsorption strength of dye to the fibre in dyeing in water compared with dyeing in IL.

حسين ايزدان

محمد ديناري

اكبر خدامي , حسن محمدي