PROCESS FOR ACTIVATING POLYSACCHARIDES, POLYSACCHARIDES MADE BY THIS PROCESS AND THEIR USE

摘要

The invention concerns a process for activating polysaccharides, wherein the polysaccharide starting material is brought into contact with liquid ammonia at an initial pressure which is higher than atmospheric pressure and at a temperature of at least approximately 25 ~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 explosi on 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 reagen ts during acylation, alkylation, silylation, xanthogenation and carbomoylation with largely homogeneous reaction processes.