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 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.

Determination of the Cellulose Scission Route in the Hydrolytic and Oxidative Degradation of Paper

“…18 It should be noted, however, that the analytical approach used in this earlier work demonstrated about 2 carbonyls produced per scission in hydrolytically degraded cotton. 19 Thus Lewin's data, which suggest that acidic hypochlorite produces about four times the number of carbonyls per scission as hydrolytically degraded cellulose, may be in agreement with our observations.…”

Flame Retarding of Wood by Chemical Modification with Bromate-Bromide Solutions

“…Ample evidence for the very slow rate of oxidation and degradation of several kinds of cellulose and pulp at the concentration ranges and temperatures used in the bromination treatments, has been documented [8][9][10][11][12]. Since the cellulose microfibrils, which are the main components of the wood cells, are responsible for the mechanical properties of the wood, it is to be expected that these properties will not be impaired by the bromination treatments.…”

“…(2) The bromination increases the density of the middle lamella, and a steric hindrance to the penetration of the brominating solution is developed. (3) The small amounts of bromine which may penetrate into the cell wall are sorbed on the cellulose but do not oxidize it [8][9][10][11][12].…”

“…In all of these cases, the flame retardant does not react with the wooden substrate and remains an extraneous material that can be washed out by rain and dew, removed by blooming, or migrating out from localized spots of the product, due to changing moisture content and vapor pressure depending on relative hummidity of the environment. The present paper reviews an extensive study carried out at the Israel Fiber Institute in Jerusalem, which was hither to only partly published, on the direct bromination of wood in an aqueous environment [2][3][4][5][6][7][8][9]. BROMINATION pulps, groundwood, as well as wood powders, was carried out in aqueous bromine solutions at a consistency of 3% and 20 ° C. The reaction takes lace according to following equations:…”

Alter the sheet resistance of carbon nanotube-coated cellulose fabric with argon plasma pretreatment

“…The yellowing of celluloses may be attributed to the oxidization of celluloses incurred by the plasma modification, yielding the presence of aldehyde groups, most likely, in the form of furan derivatives [19]. It is also of interest to note that both the colour strength and b* increase with the prolonged plasma ablation; this is not surprising since the prolonged treatment may anchor more aldehyde groups to the fabrics.…”