Molar-mass distribution of celluloses

The investigation of polymers by gel permeation chromatography has become a standard method for the determination of the molecular weight distribution. In case of cellulose and pulps the samples are mostly carbanilated or nitrated in order to get them soluble in organic solvents. In this context it is important that the derivatives obtained represent the composition of the starting material. High molecular wood pulps were carbanilated and further prepared for chromatographic separation using different methods. For bleached and unbleached pulps, the influence of the refining conditions on the molecular weight distribution and on the percentage of the soluble portion of the derivatives was investigated. It could be shown that low-molecular portions of the cellulose samples were lost applying those refining methods which included precipitation steps. For unbleached pulps, the risk existed that part of the derivatives remained insoluble and formed gel-like particles. For some pulp samples better results could be obtained by elongation of the derivatization time. Some selected pulps were carbanilated and nitrated, and the corresponding results were compared.