The yellowing tendency of modified cottons is found to depend solely on the aldehyde groups content, the ketone and carboxyl groups having no appreciable influence. Linear plots of yellowing against aldehyde groups content and against 1/DP were found and enable us to differentiate between terminal C 1 and other aldehydes in oxidized cottons. Reducing sugars show a yellowing similar to modified celluloses; pentoses and alduronic acids yield lower values than hexoses, while non-reducing sugars produce no yellowing. The ultra-violet spectra of bicarbonate extracts of modified celluloses and glucose are similar to alkaline extracts of aged celluloses. These spectra and the infra-red spectrum of the color substance and its elementary analysis point to the possibility that the colored substances are furan derivatives. It is suggested that the new yellowing method be considered as a means for the characterization of bleached cottons.

A new method for the determination of the yellowing tendency of cotton cellulose is presented. It consists in extracting the sample in a 5% sodium bicarbonate solution under reflux for one hour and measuring the color intensity of the yellow solutions obtained. The solutions strictly obey Beer's Law. The color intensity is proportional to the solubility during extraction and is linearly related to the amount of cotton used in the extraction and to the extent of hydrolytic or oxidative modification of the cellulose. The influence of the extraction time and of the stortage time of the extracts on color intensity is studied.

No abstract

No abstract

No abstract