Dextrinization degree

Lead azide is not readily dead-pressed, ie, pressed to a point where it can no longer be initiated. However, this condition is somewhat dependent on the output of the mixture used to ignite the lead azide and the degree of confinement of the system. Because lead azide is a nonconductor, it may be mixed with flaked graphite to form a conductive mix for use in low energy electric detonators. A number of different types of lead azide have been prepared to improve its handling characteristics and performance and to decrease sensitivity. In addition to the dextrinated lead azide commonly used in the United States, service lead azide, which contains a minimum of 97% lead azide and no protective colloid, is used in the United Kingdom. Other varieties include colloidal lead azide (3—4 pm), poly(vinyl alcohol)-coated lead azide, and British RE) 1333 and RE) 1343 lead azide which is precipitated in the presence of carboxymethyl cellulose (88—92). 

Glucose or maltose by selective fermentation with washed baker s yeast dextrine by difference. b Average degrees of polymerization of dextrine were calculated from their reducing values as follows ... 

The degree of polymerization of the reducing dextrine dropped rapidly to 10 and then slowly to 4. These findings are in accord with the observations of many investigators that the amylase of Aspergillus oryzae causes a very rapid decrease in the viscosities of its substrates and a very rapid disappearance of products which give color with iodine. 

Upon extensive hydrolysis of starch by either of these enzymes, only small differences were observed in the concentrations of the products or in the average degrees of polymerization of the dextrins. These comparisons were made for equivalent stages of hydrolyses and are not necessarily related to the rates of the hydrolysis of starch by these two amylases. 

Average degrees of polymerization calculated from results of acid hydrolysis of dried precipitated dextrins that remained after removal of fermentable sugars. 

According to Flory (10), the concept that proteins and carbohydrates are polymeric goes back to at least the work of Hlasiwetz and Habermann (11). In 1871 they proposed that these substances were made up of a number of species differing from one another with respect to the degree of molecular condensation. Flory also noted that Hlasiwetz and Habermann differentiate "soluble and unorganized" members of these substances, for example dextrin and albumin, from "insoluble organized" members, such as cellulose or keratin. This distinction is the precursor of the present day differentiation between non-crystalline and crystalline polymers. 

Musculus and Meyer (12) measured the diffusion rates of some starches and dextrins in 1881. The work was designed to determine the relationship of these "isomeric or polymeric" forms to the simple sugars from which they were formed. They concluded that dextrin molecules must be much larger than those of the sugars. This work, however, preceeded Raoult s (13) development of the cryoscopic technique for the determination of the molecular weights of dissolved substances, and van t Hoff s (14) formulation of the solution laws. Further, since the vapor density method was obviously inapplicable, it was not possible for them to actually determine the degree of polymerization. 

Scanning electron microscopic examination of pure, dextrinated and RD 1333 LA) 10) L. Avrami N. Palmer, Impact Sensitivity of Lead Azide in Various Liquids with Different Degrees of Confinement , PATR 3965 (1969) 11) M.F. Zimmer L.D. Lyston, Dynamic Pressure Measurements on Small Amounts of Detonating Lead Azide , Explosivst 18, No 1, 12-15 (Jan 1970) 12) R.W. Hutchinson,... 

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