Part II: The Influence of Functional Groups and the Nature of the Yellowing

Abstract

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 C₁ 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 spec trum 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.