Polarized and depolarized light scattering on solutions of cellulose in N,N-dimethylacetamide lithium chloride

In the present work, the common solvent system N,N-dimethylacetamide (DMAc) /LiCl was studied which is used, e.g., for the determination of the molecul ar weight distribution of cellulosic substrates by size exclusion chromatog raphy (SEC). Results of dynamic light scattering (DLS) experiments in the concentration range employed in SEC are presented, and discussed in terms of the solution state. A molecular dispersion of cellulose was found. The influence of the salt concentration on the solution state was shown. In solutions of higher concentrations (> 2% pulp, 6% LiCl) anisotropic part icles were found which were further investigated by depolarized dynamic lig ht scattering (DDLS). The particle size was determined by estimating the tr anslational and rotational part of diffusion. These particles can be descri bed as oblate rotational ellipsoids. The axial ratio rho was found to be 5/ 4. The half axis a was found to be 425 nm and the half axis b 530 nm.