Process for activating polysaccharides, polysaccharides produced by this process, and use thereof
First Claim
1. A process of activating a polysaccharide, which comprises the steps of:
- a) contacting said polysaccharide with liquid ammonia at a pressure higher than atmospheric pressure and at a temperature of at least about 25°
C., wherein the quantity of liquid ammonia suffices to at least wet the surface of said polysaccharide to obtain a mixture of liquid ammonia and said polysaccharide; and
b) subjecting said mixture to a pressure release, the volume available for the polysaccharide and liquid ammonia system is increased in an explosion-like manner while reducing the pressure by at least 5 bars.
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Accused Products
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° 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.
88 Citations
30 Claims
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1. A process of activating a polysaccharide, which comprises the steps of:
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a) contacting said polysaccharide with liquid ammonia at a pressure higher than atmospheric pressure and at a temperature of at least about 25°
C., wherein the quantity of liquid ammonia suffices to at least wet the surface of said polysaccharide to obtain a mixture of liquid ammonia and said polysaccharide; andb) subjecting said mixture to a pressure release, the volume available for the polysaccharide and liquid ammonia system is increased in an explosion-like manner while reducing the pressure by at least 5 bars. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. An exploded crystalline cellulose which exhibits an X-ray diffraction spectrum with peaks at the following diffraction angles 2θ
- and with the relative intensities;
Peak 11.25±
1 with the relative intensity of about 15 to 25;Peak 17±
1 with the relative intensity of about 25 to 40;Peak 20.5±
1 with the relative intensity of 100 (reference value). - View Dependent Claims (24, 25, 26, 27, 28, 29, 30)
- and with the relative intensities;
Specification