Study of the Phenomena of Diffusion and Adsorption of Direct Dyes in Viscose Fibers by the Method of Differential Dyeing

Abstract

An original method is described which allows to study the axial dyeing of viscose fiber populations (batches, yarns, fabrics). This method is characterized by the simultaneous dyeing of a few thousands fiber segments and by the statistical treat ment of the measured axial penetrations plotting frequency curves and determining their parameters). For an invariable dyeing time, the mean (or median) penetration varies considerably from one population or kind of viscose fibers to another. A thorough study of the mechanisms of differential dyeing showed that the Hermans coefficient of penetration is not a constant but varies with the dyeing time; also viscose fibers im mersed in an aqueous medium undergo a continuous modification, teaching the equi librium after a long time. The differential dyeing method can be used to study viscose fibers and to control their variation during all stages of their production and processing; this is illustrated by numerous examples of analyses of streaks in commercially dyed fabrics. The results constitute a basis for a more general study of the dyeing mecha nisms in viscose fibers and for a further extension of this method of investigation to other fibers..