Characterization of the chain length distribution of wood celluloses by gel permeation chromatography

Abstract

Abstract Cellulosics are similar to synthetic polymers in that they are composed of molecules with a given size distribution. Analysis of the chain length distribution of wood celluloses by gel permeation chromatography (GPC) is a new approach to the characterization of cellulose purity and uniformity. Cellulosics are either nitrated or acetylated prior to analysis in a tetrahydrofuran solution under ambient conditions; a column combination consisting of one each of 10 7 , 10 6 , 10 5 , and 10 4 A. columns was found to be applicable for a wide range of degree of polymerization (DP). Narrow‐distribution cellulose standards were prepared for calibration studies. Cellulosics analyzed included a 650 and 2000 DP sulfite and a 1075 DP sulfate pulp, cotton linters representing several DP levels, cellulose sponge and fibrous casing, regular and high wet modulus rayon, and microcrystalline cellulose. The extraction of a 650 and 2000 DP pulp with 10 and 18% NaOH at 20°C. was monitored by GPC. Alpha, beta, and gamma portions of cellulose were clearly distinguished; the low‐DP carbohydrate fractions reflect a predictable pattern of chain length distribution. GPC offers advantages in speed, ease of operation, and potential versatility over precipitation or solution fractionation. The method is reproducible.