Influence of Fiber Internal Environment on Dyeing Behavior of Logwood Extract Dye for Cellulosic Fibers

<p>The dyeing and mordanting behavior of cellulosic fibers such as cotton, rayon, diacetate, and triacetate, whose structural backbone is cellulose, were investigated using logwood extract dye solutions, and the effects of the internal environment of the dyeing site of each fiber on their dyeing and mordanting behaviors were discussed. All the fibers used could be dyed with the unadjusted logwood extract dye. However, the optimum dyeing temperatures for each fiber were different, with hydrophilic cotton and rayon dyeing at lower temperatures, while hydrophobic diacetate and triacetate dyeing at higher temperatures. The difference in dyeing behavior with increasing temperature between cotton and rayon suggests that the amorphous aggregation structure of rayon is less focused than that of cotton. On the other hand, diacetate and triacetate hardly form dyeable sites at low temperatures, but as the temperature rises, some regions where segmental motion is activated serve as dense dyeable sites with high dye affinity due to hydrogelation of the molecular chains constituting them. Furthermore, in all fibers, the dyed logwood dyes form metal complexes by mordanting at 90°C with iron, copper, and aluminum, but none of the central metals are presumed to be coordinated with the molecular chains that constituent the dyeing sites.</p>