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

Abstract

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 H 2O 2, NaClO or KIO 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.