EVALUATION OF SIZE-EXCLUSION CHROMATOGRAPHY AND VISCOMETRY FOR THE DETERMINATION OF MOLECULAR MASSES OF OXIDIZED CELLULOSE

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