Cellulose Viscosity—Molecular-Weight Relationships by Gel Permeation Chromatography—Low-Angle Laser Light Scattering

For years the determination of cellulose molecular weights has served as an important process and quality control parameter in the pulp and paper industry since many final end use properties of cellulose are closely related to its molecular weight and/or molecular weight distribution (MWD). A particularly convenient technique which has met with considerable success and which is often considered an industry standard is the cupriethylenediamine or CED viscosity method. In order to place CED viscosity data on an absolute molecular weight basis, we have combined the techniques of gel permeation chromatography with low angle laser light scattering (GPC/LALLS) for MWD measurements on cellulose tricarbanilate (CTC) derivatives in THF. We have found CTC preparations to be ideally suited for such applications as the reaction yields a trisubstituted cellulose with little, if any, degradation. When applied to various CTC samples having a wide range of molecular weights, the GPC/LALLS technique predicts Mark-Houwink coefficients virtually identical to published values determined for CTC in THF by conventional methods. More importantly, the procedure predicts a useful relationship between the CTC degree of polymerization and the viscosity of the underivatized cellulose in CED, and the results are compared with CED viscosity-molecular weight data originally derived from cellulose nitrates.