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Ammonia isoelectric properties

Properties A. a. are amphoteric, since they possess both NH2 and COOH groups, and their solutions are ampholytes. In the solid state and in aqueous solution between pH 4 and 9, they are zwitterions Hj N-CHR-COO" (Fig. .). With a few exceptions, they are highly soluble in water, ammonia and other polar solvents, but barely so in nonpolar and less polar solvents such as ethanol, methanol and aeetone. A. a. with hydrophilic side chains are more soluble in water. The water solublility of an A. a. is lowest at its isoelectric point, because the predominant zwitterionic form decreases the hydrophilicity of the amino and carboxyl groups. [Pg.30]

Soybean protein is a very important binder type, especially in North America. It has properties very similar to those of casein. Isolated soybean proteins are hydrolyzed, isoelectric proteins. They are used in the form of alpha and delta proteins with four different viscosities (extra low, low, medium, and high). The viscosity refers to the dissolved soybean protein, the solvent of choice being aqueous ammonia (26 Be). Proteins dissolved in this way exhibit very low sensitivity to water after drying. like casein, soybean protein is mostly used as a mixture with polymer dispersions. This combination permits the preparation of coating colors with high sohds content and a relatively low viscosity. Solids contents ofca. 60%, suitable for blade coaters, can be achieved. [Pg.109]


See other pages where Ammonia isoelectric properties is mentioned: [Pg.231]    [Pg.362]    [Pg.278]    [Pg.471]    [Pg.37]   
See also in sourсe #XX -- [ Pg.47 , Pg.231 ]




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