Evaluation of Pulps, Rayon Fibers, and Cellulose Acetate by GPC and Other Fractionation Methods

Chain length distribution of a broad spectrum of wood celluloses and cellulose derivatives was determined by gel permeation chromatography. Relative amounts of short and long chain-length species were characterized, and uniformity indices were calculated. Prefractionation was found to be a desirable approach to amplify low- and high-DP regions. This was accomplished using a 55/45 ethyl acetate/ethyl alcohol mixture to yield the low-DP fraction and with a van-ing composition acetone/water system to obtain high-DP material. Fractions of regenerated cellulose from rayon obtained by treatment with 6.5 and 10% sodium hydroxide and by acid hydrolysis were characterized. Wood celluloses and rayons were analyzed in their nitrate form, whereas cellulose acetates were studied directly. This work was aimed primarily at elucidating the gel fraction that appears in the form of a peak of apparently high-DP material, resulting in a bimodal distribution.