How alkaline solvents in viscosity measurements affect data for oxidatively damaged celluloses. Cuoxam and Cadoxen

Abstract

The effect of the degradation induced by the solvents for cellulose cuoxam and cadoxen and its dependency on the nature of the carbonyls in oxidatively-damaged cellulosics was investigated by combining a novel approach of sample regeneration and gel permeation chromatography coupled with carbonyl-selective labelling for reliable molecular characterization. The type of cellulosic pulp, degree and mode of oxidation and dissolution time were considered. Results show that the main discriminating factors in determining the degradation of oxidatively-damaged celluloses in alkaline dissolving media are: (1) the type of pulp, i.e. hemicellulose-containing pulps are more severely compromised; (2) of particular relevance, the prior oxidation mechanism, meaning not only the amount of oxidized moieties (greater oxidation, greater solvent-induced damage) but also their position on the chains (i.e. peroxide-oxidized cellulose is more unstable than hypochlorite-oxidized cellulose).

Keywords: Cadmium ethylenediamine hydroxide; Cadoxen; Cellulose degradation; Cuoxam; Gel permeation chromatography; Oxidized pulps; Tetraamminediaquacopper dihydroxide; Viscometry.