Dyeing behavior of acid dyes for wool fibers from two histologically different breeds. Merino and Lincoln.

Abstract

The influence of the histological and morphogical differences betweens Merino and Lincoln wools on the dyeing behavior was investigated with reference to the equilibrium dye adsorption and the rate of dyeing using C. I. Acid Orange 7 and Red 73 at pH 4.3. Similar absorption isotherms for Orange 7 were obtained for both intact Merino and Lincoln wools, whereas when these fibers were structurally modified by extension and supercontraction, the equilibrium dye adsorption was much higher for Lincoln wool than for Merino wool. This difference was considered to be due to the morphological difference between the wools rather than to the slight dissimilarity in the constituent proteins. The apparent diffusion parameter for Red 73 in Lincoln wools was larger than that in Merino wools of equivalent average diameter in both the intact fiber type and the modified fiber type, and the activation energy for the dye diffusion in Merino wool was different from that in Lincoln wool. These differences in the diffusion parameter and the activation energy were considered to be predominantly due to the difference in the internal structure of the wools studied.