Absorption Spectra in the Detection of Chemical Changes in Cellulose and Cellulose Derivatives

The spectral absorption of thin films of cellulose acetate, regenerated cellulose, the acetate and regenerated cellulose after oxidation with nitrogen dioxide gas, and the regener ated cellulose after oxidation with periodic acid followed by chlorous acid are recorded for the infrared from 2 to 15 microns and the ultraviolet from 215 to 400 millimicrons. The regenerated cellulose absorbed ultraviolet radiant energy only at the short-wave-length end of the region studied, and there the transmittance of a film 2.8 microns thick was only slightly reduced. The acetate and oxidized celluloses ab sorbed in this region to a greater extent but gave no narrow absorption bands. Marked changes were observed in some of the absorption bands in the infrared region in going from cellulose acetate to regenerated cellulose and to their oxida tion products. These changes were correlated with changes in the OH, CO, and COOH groups. The results indicate the possibility of estimating the amount of these groups present by spectral absorption measurements.