Energy-efficient dyeing of nylon 6 using indigo powder dyestuff after atmospheric plasma treatment at ambient pressure

Nylon 6 was treated with a dielectric barrier discharge, i.e. atmospheric plasma at ordinary air pressure. Factors influencing the dyeing process of nylon 6 using indigo blue powder were studied. The mechanism and effect of this dyeing technology were compared with those of conventional technology. Dyeing after plasma treatment at 30-50 degrees C can produce high dye uptake in a short time. Notably, dyeing after plasma treatment is beneficial for energy conservation. However, at 60-70 degrees C, the K/S values of plasma-treatment dyeing sharply increased over a short time, after which they remained largely unchanged. This finding indicated that the dyeing mechanism changed. The speed constant of dyeing after plasma treatment is 2.8 times that of conventional dyeing. The K/S values of dyeing samples after plasma treatment approached the dyeing saturation K/S value in a short time; therefore, this method of dyeing after plasma treatment achieves energy conservation and efficiency in a brief period of time. Conversely, conventional dyeing is more effective at high temperatures but consumes more energy. The adaptive electro-discharge condition is achieved under the treatment conditions of 375 W for 2 min. The chromatic aberration of the dyed samples after plasma treatment is smaller than that of conventional dyeing at 50 degrees C for 75 min.