Nitrocellulose density

Black Powder. Black powder is mainly used as an igniter for nitrocellulose gun propellant, and to some extent in safety blasting fuse, delay fuses, and in firecrackers. Potassium nitrate black powder (74 wt %, 15.6 wt % carbon, 10.4 wt % sulfur) is used for military appHcations. The slower-burning, less cosdy, and more hygroscopic sodium nitrate black powder (71.0 wt %, 16.5 wt % carbon, 12.5 wt % sulfur) is used industrially. The reaction products of black powder are complex (Table 12) and change with the conditions of initia tion, confinement, and density. The reported thermochemical and performance characteristics vary greatly and depend on the source of material, its physical form, and the method of determination. Typical values are Hsted in Table 13. 

The beater additive process starts with a very dilute aqueous slurry of fibrous nitrocellulose, kraft process woodpulp, and a stabilizer such as diphenylamine in a felting tank. A solution of resin such as poly(vinyl acetate) is added to the slurry of these components. The next step, felting, involves use of a fine metal screen in the shape of the inner dimensions of the final molded part. The screen is lowered into the slurry. A vacuum is appHed which causes the fibrous materials to be deposited on the form. The form is pulled out after a required thickness of felt is deposited, and the wet, low density felt removed from the form. The felt is then molded in a matched metal mold by the appHcation of heat and pressure which serves to remove moisture, set the resin, and press the fibers into near final shape (180—182). 

CHEMICAL PRODUCTS Ammonium Nitrate special purified product for industrial chemical use, available in solution, prill, and grained form. Also high-density grained material for formulation of military explosive compositions Composition D-2 Wax a densensitizing compound containing wax, nitrocellulose, and a wetting agent used in military explosive formulations... 

Explosive Compositions, Brisont (of High Density). The following expl compns con eg solid TNT and liquid nitric esters are described. Nitroglycerin 15—20, soluble Nitrocellulose 0—7.5, Kieselguhr 0—5, stabilizer 0-2.5, TNT 85-70%. The TNT is in the form of crushed flakes Ref J. Taylor and S.H. Davidson, BritP 578371 (1946) CA 41, 1842 (1947)... 

Solvent amount. The amount is largely determined by the amount of nitrocellulose in the composition. Figure 3 provides an example of the effect of solvent composition and amount on density. 

Earlier observations that nitrocellulose burns very quickly in a confined space-much more quickly than blackpowder— were confirmed. Since it is difficult to reduce the burning rate by physical methods only, e.g. by compressing the nitrocellulose to increase its density, attempts were made to slow down the rate of burning by the addition of phlegmatizing substances, such as glues, waxes, fats etc. 

Diagrams (Fig. 184) show the effect of the density of loading of nitroglycerine and nitrocellulose powder upon the amount of C02, CO, H2 and CH4 evolved (according to Andrew Noble [19]) in the explosion products. 

Fig. 184. Proportion of C02, CO, H2 and CH4 in products of explosion of cordite and nitrocellulose powder as a function of density, according to Brunswig [17].

After a series of accidents in the US, mainly in loading plants and depots, a more insensitive Torpex containing a greater quantity of wax was developed. The British formulation (Ref 30) for the wax desensitizer for Torpex consisted of 84/14/2 paraffm/low density nitrocellulose (12.2% nitrogen)/lecithin. The US version of this material (Ref 32), known as Compn D-l, has the following formulation (see Vol 3, C488) ... 

PETN differs from other nitric esters in failing to produce a colloid solution with nitrocellulose. This is the result of the symmetrical structure of PETN, which has a zero dipole moment. PETN is completely non-hygroscopic. Its specific gravity in crystalline form is 1.77. On compression the following density values are obtained ... 

Wet nitrocellulose can be pressed down manually in the kier by workers dressed in protective clothing, rubber shoes and woollen clothing for entering the boiler. In this way, as used in France, the loading density can be increased to 100 kg/m3. 

Stettbacher also detd densities of some smokeless proplnts but he did not give any values. He recommended to use benzene as the medium and at least a lOg sample Ref A. Stettbacher, Nitrocellulose 13, 23 26 (1942) CA 37, 4900 (1943)... 

Hexamethylenetriperoxidediamine is almost insoluble in water and in the common organic solvents at room temperature. It detonates when struck a sharp blow, but, when ignited, bums with a flash like nitrocellulose. Taylor and Rinkenbach 63 found its true density (20°/20°) to be 1.57, its apparent density after being placed in a tube and tapped 0.66, and its density after being compressed in a detonator capsule under a pressure of 2500 pounds per square inch only 0.91. They found that it required a 3-cm. drop of a 2-kilogram weight to make it explode, but that fulminate required a drop of only 0.25 cm. In the sand test it pulverized 21/ to 3 times as much sand as mercury fulminate, and slightly more sand than lead azide. It is not dead-pressed by a pressure of 11,000 pounds per square inch. It is considerably... 

Fig. 10.8. Calculation of the solubility of gases in 24 different polymers, ranging from polyethylene to nitrocellulose [120], One polymer-specific constant has to be adjusted in order to achieve good results. Experimental data are taken from Pauli [121] (HDPE = high density polyethylene, POP = polyfoxyethylene glycol), PDMS = poly(dimethylsiloxane), PTFE = poly(tetrafluoroethylene)).

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