Abstract: The invention relates to a method for improving the colour index of cellulose esters especially consisting of cellulose acetate. According to the inventive method, a delignified eucalyptus pulp is subjected to a preliminary treatment in order to remove pigments or chromophoric substances, and the process-modified eucalyptus pulp obtained is converted into cellulose esters in a conventional manner. The inventive method is characterized in that a delignified eucalyptus pulp having a cellulose content of more than approximately 80 wt. % and a pentosan content of more than approximately 1 wt. % is extracted by means of a solvent which dissolves oligomer pentosans but not the pulp of the delignified eucalyptus pulp, especially at a temperature of up to approximately 200 ° C. and a pressure of up to approximately 30 bar. The inventive method leads to an improvement in the colour index of cellulose esters or the fibres and filaments produced therefrom, in an economical and technically simple manner.

Abstract: The invention concerns reactive cellulose, i.e. cellulose having in particular a very low degree of crystallinity obtainable with a high degree of purity. Said novel reactive cellulose is particularly used as raw material for making cellulose ethers. The invention is characterized in that the reactive cellulose is substituted by organic groups according to a degree of substitution, DS, of less than 0.2, preferably between 0.04 and 0.2.

Abstract: The process for activating polysaccharides consists of contacting the polysaccharide with liquid ammonia at an initial pressure which is higher than atmospheric pressure and at a temperature of at least approximately 25.degree. C., the amount of liquid ammonia being sufficient at least for wetting the surface of the polysaccharide starting material which is then expanded. The volume available for the polysaccharide/liquid ammonia system is enlarged in the manner of an explosion by lowering the pressure by at least 5 bar. The process is particularly suitable for activating cellulose, guar gum, starch and chitin. The process enables cellulose to be modified in a novel manner. The activated polysaccharides display higher reactivity and improved elimination of reagents during acylation, alkylation, silylation, xanthogenation and carbomoylation with largely homogeneous reaction processes.

Abstract: The process for the treatment of cellulose for activation for subsequent chemical reactions by bringing the cellulose in contact with liquid ammonia at a pressure higher than atmospheric pressure in a pressure vessel and subsequent expansion by rapid reduction of the pressure to atmospheric pressure, is carried out by using a cellulose pulp of an alpha-cellulose content of at least 92 mass %, letting the ammonia act on the pulp at room temperature or at a temperature higher than room temperature, after the expansion, removing the ammonia then still remaining in the pressure vessel except for a minimum content at which the state of activation reached by the action of the ammonia is still maintained and finally replacing the residual ammonia still needed to maintain the state of activation by another swelling or inclusion agent.