Relationship between cellulase treatment and the dyeability with a direct dye for various kinds of cellulosic fibers

The cellulosic fibers were dyed to equilibrium with Congo Red before and after cellulase treatment. The fibers examined were rayon, polynozic, cupra, flax, and cotton. It was found that the volume term for dyeing (V) was associated with weight loss (WL) caused by the cellulase treatment, for the original fibers. Apparent affinity for dyeing (AF) for the cellulase-treated fibers was calculated using a constant value of V obtained for each kind of the original fibers. The results led to the assumption that there would be two kinds of the regions that could be accessible to dye. One would be the region that was readily digested by the enzymatic hydrolysis. The other would be the region that was additionally developed by the attack of cellulase. The previously dyed fibers were hydrolyzed by cellulase. It was found that the physical bondings that formed between cellulose and Congo Red molecules would block the hydrolysis by cellulase for all the fibers examined. It was also assumed that there would be a region that could be accessible to cellulase but not entirely to Congo Red.