Evaluation of the accessibility of celluloses by the intrinsic viscosity ratio [η] acetone cell.nitr. / [gh] CuEn unsubst.cell.

Summary Standarization of the nitration procedure as well as of the conditions of viscosimetric measurements on cellulose nitrates and unsubstituted celluloses leads to a constant Intrinsic Viscosity Ratio ] _Acetone ^Cell.nitr. / gh] _CuEn ^{Unsubst.cell.} = 1.95±0.05, independently from the range of DP. Since nitration under the standarized conditions occurs without degradation and delivers a reproducible constant degree of substitution of DS = 2.90±0.02, intrinsic viscosity ratios lower than 1.90 indicate a diminished accessibility of the respective cellulose. Determination of the intrinsic viscosity ratio reveals, therefore, the possibility to evaluate the accessibility of a cellulose sample.