Dyeing kinetics of radiation-grafted polyester fabric using different dyes

Abstract

Dyeing kinetics of radiation-grafted and ungrafted polyester fabrics using basic, direct and disperse dyes have been studied in the temperature range 283-363 K and then compared. The effects of graft yield, pH of the dye solution, dyeing time, dye concentration and dyeing temperature on the colour difference of ploy (ethylene terephthalate) fabric have been studied for basic Rhodamine Red, direct Congo Red and Disperse Red dyes. The colour difference increases rapidly with the increase in graft yield and tends to level off at higher degrees of grafting. The best dyeing conditions are achieved at pH 9, 5.5 and 5.5 for direct, basic and disperse dyes respectively. The kinetic parameters (rate, rate constant, order, activation energy and pre-exponential rate constant) have also been evaluated for the different dyes. Analysis of the kinetic parameters and dyeing mechanisms reveals that the dyeing of polyester fabric is diffusion-controlled, and the dyeing rates follow the order: basic dye (1% grafted) >> direct (1% grafted) > disperse (1% grafted) > disperse (with a carrier) > disperse (without a carrier). Grafting improves significantly the dyeing affinity of polyester fabric towards basic, direct and disperse dyes.