DETERMINATION OF THE DEGREE OF SUBSTITUTION IN BENZYLCELLULOSE BY SPECTROSCOPIC METHODS

Several possibilities for the DS determination in benzylcelluloses wit h low DS values (DS < 0.1)have been studied. Different spectroscopical techniques have been under investigation. UV-VIS transmission measure ments of the benzylcelluloses dissolved in cadoxen gave very precise r esults but required a time-consuming dissolution of benzylcellulose. I n addition, these measurements are restricted to DS < 0.12, due to lac king solubility of benzylcelluloses with higher DS in cadoxen. FTIR-an d NMR spectroscopical measurements proved to be not applicable or too inaccurate. NIR reflection measurements on benzylcellulose discs in co njunction with a multivariate calibration technique (PLS 1) gave preci se results in a reasonable time and, addition ally, the moisture conte nt of the cellulose derivative could be determined simultaneously. Inf ormation time could also be reduced by Raman reflection measurements, allowing for DS determinations in the entire DS range (0 < DS < 3).