Evaluation of size-exclusion chromatography and viscometry for the determination of molecular masses of oxidised cellulose

The molecular masses of oxidised cellulose samples from two different sources were determined by size-exclusion chromatography (SEC) and viscometry. SEC was performed at room temperature using a cross-linked polystyrene-divinylbenzene column and 1% LiCl (w/v) in N,N-dimethylacetamide (DMAc) as the eluent. Cellulose samples were oxidised using aqueous solutions of H2O2, NaClO or KlO(4), and dissolved in the LiCl-DMAc solvent system using activation with water and a solvent exchange procedure. Viscometry in the cupriethylenediamine (CED) solvent system was performed following the standard technique. Oxidised cellulose samples are prone to degradation by alkalis, While the dissolution in LiCl-DMAc was shown not to have a degrading effect, the oxidised cellulose samples are unstable in the highly alkaline CED solvent, thus introducing a systematic error to the viscometric measurements. A stabilising reduction procedure usually recommended for such samples was tested, and shown to be advantageous, although degradation cannot be completely avoided. (C) 1998 Elsevier Science B.V.