Significance of the intrinsic viscosity ratio of unsubstituted and nitrated cellulose in different solvents

It has been studied the intrinsic viscosity ratios of cellulose solutions in different solvents and of the corresponding nitrates dissolved in aceton using cellulose samples from different origins and with different degrees of polymerization. The results demonstrate that with FeTNa and CdEn as solvents, molecular dispersed solutions are only produced with cellulose having a DP≤3000. FeTNa is limited to cotton cellulose only. Contrary to this, the intrinsic viscosity ratio [η]/[η] shows independence from the range of degree of polymerization and the origin of cellulose, confirming thus once more the polymeranalogous course of nitration. Its value referred to a degree of substitution S = 2.90±0.02, to absolute dry and pure cellulose and to standardized viscosity measurements amounts [η]_Ac/[η]_CuEn = 1.95±0.05. Determination of the intrinsic viscosity ratio permits, therefore, to obtain information in respect of the polymeranalogous and homogeneous character of the cellulose nitrate, and, in connection with determinations of yield of nitration, in respect of the purity of the corresponding unsubstituted cellulose. Basing on the constant value of the intrinsic viscosity ratio [η]_Ac/[η]_CuEn, and using the quotients [η]_FeTNa/[η]_CuEn and [η]_CdEn/[η]_CuEn, there has been derived the [η]-DP-relationships for unsubstituted cellulose in the respective solvents.