| abstract |
The invention relates to a method in which the starting polysaccharide comes into contact with liquid ammonia at an initial pressure higher than atmospheric and at a temperature above about 250C, the amount of liquid ammonia being sufficient to at least wet the surface of the starting polysaccharide, which is then subjected to blasting. The volume given to the polysaccharide / liquid ammonia system is explosively increased by reducing the pressure to over 5 bar. The method is particularly suitable for activating cellulose, guar gum, starch and chitin and allows the cellulose to be modified in a new way. Activated polysaccharides show higher reactivity at lower reagent consumption in acylation, alkylation, silylation, xanthogenation and carbamoylation, and the reaction processes are much more homogeneous. |