Effect of dodecyl dimethyl benzyl ammonium chloride on dyeing kinetics and thermodynamics of spandex fibers dyed with acid dye

Spandex fiber has been widely used in clothing. Adding a small amount of spandex to textiles can greatly improve the elasticity, wear resistance, and other mechanical properties. But it is difficult to color it into a deep hue with acid dyes. The main purpose of this paper is to investigate how the cationic dyeing auxiliary dodecyl dimethyl benzyl ammonium chloride (DDBAC) can effectively improve the dyeability and dyeing depth of spandex fibers, and its influence on dyeing kinetics and thermodynamics of spandex fiber. The results showed that adding DDBAC could increase the potential of spandex zeta. Kinetically, when spandex adsorbed acid dyes, adding DDBAC could decrease the dyeing rate constant, and improve the dyeing equilibrium concentration and half-dyeing time. Thermodynamically, without DDBAC, the adsorption isotherm of spandex to Acid Red 414 conforms to the Langmuir model. The adsorption isotherm of spandex to Acid Red 414 after DDBAC is added is not entirely obedient to the Langmuir partition type but is close to the Langmuir + Nernst binary adsorption model. Meanwhile, the new binary saturation adsorption value S increased with the increase of temperature and DDBAC dosage and tended to occur more in the Nernst-type partitioning mechanism.