Nitrocellulose gun propellants

Table 4. Thermochemical, Thermodynamic, and Performance Characteristics of Nitrocellulose Gun Propellants ...

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. 

Designation for double base (nitroglycerine-nitrocellulose) gun propellants in the United Kingdom. 

Black powder is mainly used as an igniter for nitrocellulose gun propellants and to some extent in safety blasting fiises, delay fuses, and firecrackers. Potassium nitrate black powder (74 wt percent plus 15.6 wt percent carbon, 10.4 wt percent sulfur) is used for military applications. The slower-burning, less costly, and more hygroscopic sodium nitrate... 

All five processes requite plasticization of the nitrocellulose to eliminate its fibrous stmcture and cause it to bum predictably in parallel layers. Mechanical working of the ingredients contributes to plasticization and uniformity of composition. The compositions of representative nitroceUulose-based gun propellants are shown in Table 7. 

Gun propellants have traditionally been fabricated from nitrocellulose-based materials. These fibrous materials can be manufactured in granular or stick forms (grains)... 

Gun propellants are manufactured by three different methods (i) solvent method (ii) semi-solvent method and (iii) solventless method. The solvent method is that most commonly used for the manufacture of gun propellants. Selection of the method for manufacture basically depends on the properties of the raw materials and the propellant formulation. While there are limitations for the manufacture of gun propellants by solventless and semi-solvent methods, the solvent method may be applied for almost every gun propellant formulation. The solid-liquid ratio of the ingredients and the type of nitrocellulose used usually decide the feasibility of manufacture by the solventless method. Some characteristics of solid gun propellants are given in Table 4.1. 

Nitrocellulose can be quite hazardous if left to dry out completely therefore, it is usually stored and transported in 30% water or ethanol. Nitrocellulose is often dissolved in solvents to form a gel. For example, commercial explosives used for blasting purposes contain nitrocellulose dissolved in nitroglycerine, and some gun propellant compositions contain nitrocellulose dissolved in a mixture of acetone and water. 

In order to raise the Q value of single-base propellants and to increase the pressure of the gas inside the gun barrel, nitrocellulose is mixed with nitroglycerine to form double-base propellants. Double-base propellants have a Q value of about 4500 J g 1 and are used in pistols and mortars. The disadvantage of double-base gun propellants is the excess-... 

Propellants include both rocket and gun propellants. Most rocket propellants are either Hazard Class 1.3 composites, which are based on a rubber binder, and ammonium perchlorate (AP) oxidizer, and a powdered aluminum (Al) fuel or Hazard Class 1.1 composites, which are based on a nitrate ester, usually nitroglycerine (NG), nitrocellulose (NC), HMX, AP, or polymer-bound NC. If a binder is used, it usually is an isocyanate-cured polyester or polyether. Some propellants contain combustion modifiers, such as lead oxide. 

Nitrocellulose high performance gun propellant [military grade gunpowder double based)... 

DNAN forms colorless crystals with a melting point of 120 Celsius. It is fairly soluble in hot water, hot ethanol, methanol, and acetone. It is less soluble in cold water, cold ethanol, and insoluble in chloroform, benzene, ether, and petroleum ether. DNAN is somewhat hygroscopic, and moisture slowly decomposes it—should be stored in a desiccator. A small sample bums leaving a residue of carbon when ignited—a small sample can be detonated by the blow of a hammer. DNAN can be used in explosive compositions when alloyed with TNT, or other low melting secondary explosives, gun propellants with nitrocellulose, nitro starch, or nitroglycerine, and rocket propellants when mixed with ammonium perchlorate. DNAN also demonstrates usefulness for priming mixtures with lead azide, lead styphnate, or diazodinitrophenol, and for use in fireworks. ... 

Nitrocellulose compositions used in explosive applications vary from 10 to 13.5 percent of nitrogen. The thermal stability of nitrocellulose decreases with increasing nitrogen content. It dissolves in organic solvents to form a gel. The gel is used as gun propellant, double-rocket propellant, and gelatine and semi-gelatine commercial blasting explosives. 

Nitroglycerine is one of the most important and most frequently used components of explosive materials together with nitroglycol, it is the major component of gelatinous industrial explosives. In combination with nitrocellulose and stabilizers, it is the principal component of powders, gun propellants and smokeless solid rocket propellants (- double base propellants). 

Because of the low temperature of explosion, about 2,098°C, nitroguanidine is used in triple-base propellants that are practically flashless and less erosive than nitrocellulose-nitroglycerin propellant of comparable force. When used by the Germans in World War II in antiaircraft guns, a nitroguanidine propellant increased the barrel life from 1,700 firings to about 15,000 firings. 

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