| Since the Tg of aramid fiber reached 275℃, the dyeing with conventional dyeing method at 130℃for aramid fiber was more difficult. In order to comply with the goal of green dyeing and finishing, the development of an eco-dyeing technology for aramid fabric was urgently needed. The disperse dyeing process adding environment-friendly carrier for aramid fabric was a convenient, effective, energy-saving and safe dyeing process. So the study on the dyeing process with disperse dye and carrier at high temperature and dyeing mechanism for aramid fabric had both academic value and more practical significance.In this paper, the MPIA fabric was taken as the main research object. The optimum dyeing process with disperse red SF-B, disperse yellow S-4G and disperse dark blue UN-SE at high temperature and pressure for aramid fabric was obtained through the single factor analysis and orthogonal experiments. The dyeing temperature, dyeing time, pH value and liquor ratio were 140℃, 60min, 5.5 and 1:20 respectively. Adding environment-friendly carrier on this basis, the optimum dyeing process with disperse dye and carrier at high temperature for aramid fabric was determined. The concentration of carrier Cindye Dnk was 30g/L and the dyeing temperature was 130℃. The results showed that the dyeing process with disperse dye and carrier at high temperature for aramid fabric could increase the dyeing properties of aramid fabrics obviously. The dye-uptake and the K/S value of dyed fabric were above 77% and 11 respectively. The washing fastness of dyed fabrics was equal to or above 2-3 grades. The rubbing fastness and light fastness of dyed fabrics were equal to or above 3 grades. The ironing and heat pressure fastness of dyed fabrics were equal to or above 4 grades.The effect mechanism of carrier Cindye Dnk on the disperse dyes was studied through color tone, solubility, size, dispersed state and stability of the disperse dyes by UV-Vis Spectrophotometer, Dynamic Light Scattering Nano-Particle Size Analyzer and FESEM. The results indicated that the carrier Cindye Dnk had no effect on the color tone and the structure of disperse dyes. However, it improved their solubilities in water and reduced their sizes. The effect mechanism of carrier Cindye Dnk on structure and properties of the aramid fiber was studied through TGA,XRD,FTIR,SEM and OM. The results showed that the carrier Cindye Dnk didn't affect the surface and chemical structure of the aramid fiber; its structure was similar to that of aramid fiber, thus it conformed to the rule of like dissolves like. The thermal properties and physical and mechanical properties of aramid fiber were strengthened slightly by the carrier Cindye Dnk. However, the internal crystal structure and flammability were not changed. Moreover its dyeing permeability was significantly improved. The diameter, cross sectional area and porosity of aramid fiber were increased.Taking the disperse yellow S-4G as an example, we studied the effect mechanism of carrier Cindye Dnk on dyeing process through the kinetics and thermodynamics of aramid fiber dyed with disperse dye. The study of kinetics indicated that the dyeing rate constant and diffusivity of disperse dye on aramid fiber were increased by the carrier Cindye Dnk, and the half-dyeing time was shorten. Thermodynamic analysis showed that the adsorption isotherm type of aramid fiber dyed with disperse dye at low concentration was not affected by the carrier Cindye Dnk.They were both generally consistent with Nernst-type adsorption. Moreover, the distribution coefficient on the aramid fiber and in the dyebath of disperse dye, dyeing affinity and enthalpy were increased by carrier Cindye Dnk, and the dyeing entropy was decreased.
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