A: nitrocellulose powder

The alcohol (usually refined to 95-96%) must not be acid. To make a 100 cm3 sample of alcohol neutral towards phenolphthalein no more than 1.6 cm3 of 0.1 N NaOH is required. A larger quantity of acid is detrimental since it may adversely influence its stability and gives a dark powder. The alcohol should not contain nitrites. A nitrocellulose powder plant should be equipped with a plant for the distillation of alcohol. 

Ether, in its common commercial form, is sufficiently pure to be used in admixture with alcohol. Its acid content should not exceed 40 mg (calculated as H2S04) per litre, nor should it contain nitrites. A nitrocellulose powder plant must include a plant for the manufacture of ether. 

Trinitronaphthalene appears to be a genuine stabilizer for nitrocellulose, a true inhibitor of its spontaneous decomposition. Marqueyrol found that a nitrocellulose powder containing 10 per cent of trinitronaphthalene is as stable as one which contains 2 per cent of diphenylamine. The trinitronaphthalene has the further effect of reducing both the hygroscopicity and the temperature of combustion of the powder. 

A-E = single base powder A nitrocellulose powder D DNT added F-M = double base powders F = nitrocellulose nitroglycerine G = nitrocellulose-diglycol dinitrate K = ball powder N-P = triple base powders V-W = porous powders (german) TMEMT = trimethylenetrinitrosamine 71... 

Franklin patented a nitrocellulose powder containing nitroguanidine and an oxidizing agent such as barium nitrate, and superficially impregnated with a deterrent material such as dinitrotoluene. 

Many methods have been proposed and are used to study the thermal stability of propellants and to ensure the absence of possible autocatalysed decompositions during storage. None are sufficiently reliable to merit individual description. In practice, stabilisers are added, the usual being diphenylamine for nitrocellulose powders and symmetrical diethyl diphenyl urea (carbamate or centralite) for double base propellants. Provided a reasonable proportion of stabiliser remains, the propellant can be assumed to be free from the possibility of autocatalytic decomposition. The best test of stability is therefore a chemical determination of the stabiliser present. 

FIG. 2.5 Ballistite, a "smokeless powder" consisting of 60% nitrocellulose and 40% nitroglycerine, produces a thermogram with no transitions detectable prior to exothermic decomposition above 150 "C. 

Double base A smokeless powder that contains both nitroglycerin and nitrocellulose. 

HG 34/4, contained 34g of a special powder made of a mixture of Nitrocellulose, DEGDN Nitrognanidine. The igniter was 4g of strongly pressed Black Powder Ref 1) E.R. von Herz, Explosivst, 1954,... 

Proteins are blotted onto a nitrocellulose membrane by diffusion for 1 h at 60°C. Non-specific sites on the nitrocellulose membrane are blocked with 50 g/1 powdered milk dissolved in PBS/0.1% Tween-20. The membrane is washed in PBS/0.1%... 

The same author [27] gives some data on a propellant which is intermediate between composite and double base propellants. It is composed of ammonium perchlorate and a nitroglycerine-nitrocellulose powder (double base powder). 

In Russia, Mendeleyev [12] worked out a method for the manufacture of smokeless powder from pyrocellulose, i.e. relatively high-nitrated (12.5% N) nitrocellulose soluble in a mixture of ether and alcohol. In 1892 the manufacture of this powder was started for naval guns. Nitrocellulose powder of this type was soon adopted for military purposes in the U.S.A., where nitrocellulose powder became known as single base powder . 

The specific gravity of semicoiloidal nitrocellulose powder with a mixture of ether and alcohol as a solvent usually ranges from 1.54-1.63, although the specific gravity of nitrocellulose itself is 1.66. This indicates a certain porosity of the powder. The pores are filled either with air or with traces of residual solvent. According to Brunswig [17] 100 g of nitrocellulose rifle flake powder contains 4-8 cm3 of the air. 

Nitroglycerine powder—completely or almost completely wholly colloidal—is less porous, therefore more difficult to ignite than nitrocellulose powder and requires a stronger priming. 

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].

Generally speaking, nitroglycerine powders give a higher heat of explosion, so that the temperature of their products is higher than that in nitrocellulose powders. 

Rideal and A. J. B. Robertson [23] suggest that initiation of the thermal explosion of nitrocellulose is preceded by liquefaction. Very likely the same would apply to nitrocellulose powder. 

Nitrocellulose powders (U.S.A.) Heat of explosive decomposition (water liquid) kcal/kg Gas volume (water vapour) l./kg Linear coefficient for rate of burning from one surface in./sec/in2... 

Smokeless powders have low sensitiveness to impact and friction. They do not ignite when hit by rifle bullets and are thus fairly safe to handle in war-time. Nevertheless there have been accidents caused by the sudden ignition of nitrocellulose powder brought about by the violent friction between the sharp edge of a heavy bin and powder scattered on the floor. 

According to Kast [28] nitrocellulose powder does not detonate even when very strongly initiated (e.g. 50 g of picric acid or 100 g of tetryl), but may explode with a rate from 1000 to 1800 m/sec. 

Burlot found similar figures. He also examined the effect of the impact of a falling weight or of a rifle bullet. Only deflagration occurred — there was no detonation. However in his later experiments Burlot [31] has found that nitrocellulose powder (poudre BM9—in strips) can detonate under the shock produced by a rifle bullet D (caliber 8 mm, 7.5 g) having a velocity above 1200 m/sec (e.g. 1266 m/sec). 

The ignition temperature of nitroglycerine smokeless powder is approximately 180°C and that of nitrocellulose powder about 200°C. Ignition with a direct flame,... 

Fig. 189. Electric (static) charge of nitrocellulose powder as a function of moisture content, according to Nash [32],...

Langevin and Biquard [33] showed that the evaportion of a liquid (alcohol, ether, benzene) does not electrify the residual solvent. Hence evaporation of the solvent in driers cannot lead to electrification of the powder. In the opinion of these authors nitrocellulose powder may be ignited by the discharge of the condenser at a voltage of 3000 V, if the condenser charge is greater than 0.3 fiF. 

The lower stability of smokeless powder in comparison with that of nitrocellulose is accounted for by its content of residual solvent and of the oxidation products of this solvent. Since in a finer powder the ratio of the surface to weight is high, the oxidation processes are more intense. A larger amount of decomposition products of residual solvent is formed by oxidation, and their destructive effect... 

The following findings point to the harmful effect of air on the stability of green nitrocellulose powder, i.e. freshly pressed and containing a considerable quantity of solvent (alcohol and ether) (Table 171). 

Atmospheric humidity has a deleterious effect on the stability of powder. Storm [54] reports that a good nitrocellulose powder, which withstood heating at a temperature of 65.5°C for 400 days without marked decomposition, showed evident decomposition in 175 days when stored at the same temperature in an atmosphere saturated with water vapour. Powder which passed the first test subsequently withstood heating for 5 hr at a temperature of 135°C without explosion, whereas powder from the second test exploded at the same temperature after 10 min. 

Fig. 194. Stability of nitrocellulose powder at 110°C (measured as a reduction of weight)...

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