THE SAPONIFICATION OF CELLULOSE TRIACETATE FIBER

Abstract

Cellulose acetate fibers of various acetyl contents were obtained from the saponification of cellulose triacetate (CTA) fibers with 0.01_??_0.2 N NaOH and 1.0_??_1.8 N HCl solutions. X-ray diffraction and dynamic viscoelastic property of these cellulose acetate fibers were measured and the deacetylation mechanism of cellulose triacetate fibers is discussed in connection with their dyeing behavior.When CTA fibers were saponified in NaOH solutions, the CTA crystals and αa absorption due to micro Brownian motion of CTA amorphous molecules disappeared at the same concentration of NaOH solution. This result indicates that deacetylation proceeds annularly from the outside of the fiber as obserbed from the dyeing behavior.On the other hand, saponification behavior with HCl solutions was fairly different from that of NaOH solutions. In the lower concentration of HCl solutions, saponification reaction didn't take place, but there was a change in the structure of CTA fiber, such as relaxation of the CTA chain molecules. In the middle concentration, the saponified fibers could be dyed with a direct dyestuff, but the CTA crystals still remained. In the higher concentration, the saponification proceeded to the crystalline regions, but the cellulose fibers formed with HCl saponification had a low thermal stability and low crystallinity. The saponification process of CTA fibers with HCl solution, therefore, does not agree with that speculated from their dyeing behavior.