Determination of degree of polymerization of cellulose in ligneous papers

In the past, many attempts have been made to determine the degree of polymerization (DP) of cellulose in ligneous pulps or papers. Frequently, the methods employed caused severe depolymerization of the cellulose. The present paper provides a detailed procedure of DP determination of cellulose for both lignin-free and ligneous papers. The proposed method is based on viscosity measurements of cadoxen solutions of cellulose. Prior to dissolution in cadoxen, ligneous samples are partially delignified by a modified chlorite method, under conditions preventing any substantial depolymerization of cellulose. Results of preliminary experiments carried out on groundwood newsprint papers provide strong evidence of reliability of DP values so determined.