Diffusion of dyes in polyester fibers. III. Time delay in establishment of the equilibrium concentration of dye at fiber surface
Abstract
In the dyeing process of the copolyester fiber Dilana with the disperse dye Synthene Scarlet P3GL, a deviation from the simple model of Fickian sorption occurs. It manifests itself as a time delay in establishment of the equilibrium dye concentration at the fiber surface. As has been stated, the variation of Cs (the surface dye concentration) with time of dyeing fits the equation; Cs = C∞ (1− e−βt). Regarding the relation of Cs to t, the diffusion coefficient of the dye in the studied fiber has been calculated by the theoretical equation reported in Crank's monograph. It has been proved that the experimental data on kinetics of dyeing the fiber Dilana with Synthene Scarlet P3GL fit considerably better the tested equation than the classical Hill's equation.