MOLECULAR INHOMOGENEITY OF CARBOXYMETHYL CELLULOSE AS MEASURED BY HIGH-SPEED SEDIMENTATION AND FRACTIONATION

The inhomogeneity of monosubstituted carboxymethyl cellulose with resp ect to substitution degree and molecular mass was determined using fra ctionation and high-speed centrifugation. The inhomogeneity of the deg ree of substitution was low, whereas the inhomogeneity of molecular ma sses was considerable: parameter M(z)/M(w) ranged from 1.8 to 3.5. The experimental data supports a linear relationship between the standard deviation of the displacement distribution and the mean displacement of the sedimentation boundary in high-speed sedimentation experiments. Thus, the polydispersity of carboxymethyl cellulose specimens can be adequately described using the method of moments with linear approxima tions. The method of high-speed sedimentation was used for obtaining c haracteristics of carboxymethyl cellulose in different solvents; the r esults were compared.