ON THE CHARACTERIZATION PRINCIPLES OF SOME TECHNICALLY IMPORTANT WATER-SOLUBLE NONIONIC CELLULOSE DERIVATIVES

Principles are developed and discussed for a detailed characterization of water soluble polymers (cellulose ethers) as to hydrodynamic and t hermodynamic behaviour, molecular size in solution in solvents of vary ing hydrophilicity and aggregation. In particular, the application of dynamic light scattering (DLS) and size exclusion chromatography is di scussed and compared with static light scattering and viscometry. Resu lts are given for eight non-ionic cellulose ether samples concerning p hase separation properties, intrinsic viscosity, Huggins' constant, we ight and number average molecular weight, second virial coefficient, r adius of gyration, molecular weight distribution, and hydrodynamic par ticle size parameters from DLS. The results are also discussed in term s of chemical properties such as degree and type of substitution and c loud point. Values of refractive index increments have been measured f or all samples in the two solvents used.