SPECTROSCOPICAL CHARACTERIZATION OF CELLU LOSE DERIVATIVES

Numerous cellulose derivatives experience increasing economic relevanc e und reach large scale production. Their physical, chemical and also biological properties are mainly determined by the degree of substitut ion (DS). Conventional analytical techniques for the monitoring of pro cesses and the characterization of products with respect to DS are som etimes timeconsuming and very labourintensive. With growing importance of work efficiency also in the field of analytical chemistry analytic al techniques are requested with maximum efficieny and still acceptabl e precision. The consequent introduction of new spectroscopic instrume ntation allows to increase time- and labourefficieny of the characteri zation of cellulose derivatives. DS-determinations are rapidly perform ed by Raman- as well as by NIR-spectroscopic techniques with adequate precision also in the DS range below 0.1. Therefore a selection of ana lytical procedures will be discussed in comparison to conventional app roaches. It will be demonstrated that common restraints towards the qu antitative application of Raman- and NIR-spectroscopy with respect to solid materials are unfounded. Confocal Raman spectroscopy is well sui ted for the purpose of the characterization of dialysis membranes prod uced from cellulose derivatives. By this technique the lateral distrib ution of the DS on the membrane surface is readily obtainable, as will be demonstrated for benzylcellulose dialysis membranes. Additionally, remote Raman sensing is a valuable tool for the determination of kine tic and chemical engineering data, which are obtained in a direct and noninvasive in-line manner by using remote Raman sensors. This straigh tforward approach has distinct advantages over the conventional off-li ne one. Examples of application are given for the field of cellulose c hemistry by the homogeneous synthesis of cellulosephthalate and cellul oseacetate.