Nitrocellulose nitrogen content

Treatment of nitrocellulose Nitrogen content o/ /o Viscosity of ether-alcohol solution sec Solubility in 95% alcohol 0/ /o Copper number after denitration... 

Type of nitrocellulose Nitrogen content % Time of boiling at 134°C min Intrinsic viscosity V... 

No. Type of nitrocellulose Nitrogen content % H2SC>4 as free acid 0/ /o H2SO4 as nitrocellulose hydrogen sulphate %... 

Dry nitrocellulose, which bums rapidly and furiously, may detonate if present in large quantities or if confined. Nitrocellulose is a dangerous material to handle in the dry state because of sensitivity to friction, static electricity, impact, and heat. Nitrocellulose is always shipped wet with water or alcohol. The higher the nitrogen content the more sensitive it tends to be. Even nitrocellulose having 40% water detonates if confined and sufftcientiy activated. AH large-scale processes use nitric—sulfuric acid mixtures for nitration (127—132). 

Fig 12 Change of nitrogen content in nitrocellulose as a function of water concentration in nitrating mixtures according to Miles (Ref 44)... 

Composition of the nitrating mixture, % Composition of the spent acid, % Cellulose to acid ratio 1 j Nitrogen content of nitrocellulose. %... 

Cellulose Chemistry , London (1947), 245—47 22) B.T. Fedoroff, Rapid Method for the Determination of Nitrogen Content of Nitrocellulose by the Ferrous Ammonium Sulphate Method , PACLR 122871 (1948) 23) J. Pearson... 

The nature of the nitrocellulose used is of particular importance in explosives if freedom from exudation of free nitroglycerine during storage is to be avoided. Nitroglycerine is only a poor solvent for nitrocellulose and stability of the gel depends on continuous formation and breakdown of gelled structures. The distribution of nitrogen content and viscosity, even in the individual fibres of the nitrocellulose, is therefore of paramount importance. 

Nitrocellulose is usually handled wet and containing approximately 30% of water. Under these conditions it can be considered as a nonexplosive material when the nitrogen content does not exceed 12-6%. More highly nitrated cellulose is known as guncotton and is explosive even when moderately wet. When dry, nitrocellulose of all types is an extremely sensitive and dangerous explosive. Dry nitrocellulose is required for use in certain types of explosives and is then prepared by slow drying of the wet material in a current of warm air. 

Guncotton. Nitrocellulose of high nitrogen content (13-35 to 13.45%). It is described in Vol 2 of Encyd, under CELLULOSE NITRATE, p C106-R to C108-R... 

A propellant which consists of nitrocellulose (NC) as the only explosive ingredient is called a single-base (SB) propellant. The formulation consists of 90% or more of NC with a nitrogen content of 12.50-13.25%. NC is gelled with the help of a... 

More recently Demougin and Landon [67] examined the stability of nitrocellulose powder containing 1.02-7.8% diphenylamine at a temperature of 110°C. After 160 hr of heating they determined the nitrogen content in nitrocellulose isolated from powder (Table 174.). The initial content of diphenylamine in the sample was 7.8% on heating for 180 hr at a temperature of 110°C it was reduced to 1%. 

Marqueyrol [74] reported experiments carried out in France over a period of 15 years to compare the efficiency of various stabilizers. The results are shown in Table 175. In addition to amyl alcohol and diphenylamine, the action of N-nitrosodiphenyl-amine (diphenylnitrosamine), carbazole, diphenylbenzamide, nitronaphthalene and naphthalene was also tested. The powder was stored at temperatures of 40, 60 or 75°C. The experiments were stopped when the powder showed signs of intense decomposition, giving off nitric oxides. This was also manifested by a sudden fall pf the nitrogen content in nitrocellulose isolated from the samples. 

In the manufacture of nitrocellulose powders the water is displaced with alcohol. This method was proposed by Lundholm and Sayers [3] and widely used in many countries [4, 5]. Despite the simplicity of the idea the dehydration process is rather complicated. It is influenced by such factors as the solubility of nitrocellulose in alcohol and the ability of nitrocellulose to swell under the influence of alcohol the lower the solubility of nitrocellulose in alcohol, the more easy dehydrated with alcohol. Since, however, the solubility of nitrocellulose depends primarily on its nitrogen content dehydration is easier with the higher nitrated types of nitrocellulose. 

Nitrocellulose for the manufacture of powder must meet requirements of chemical stability, nitrogen content and solubility in a mixture of alcohol and ether according to the regulations discussed in the chapter on nitrocellulose. 

The more modem approach to the problem of mixing nitrocellulose consists of mixing defined types of nitrocellulose in the nitrocellulose factory itself. In this case the two forms of nitrocellulose are mixed under water in mixers as described in Vol. II, p. 374. The water is then centrifuged and the mixture dehydrated with alcohol. This method, however, creates certain inconvenience to the powder factory which loses the possibility of changing (within certain limits) the composition of the mixtures, i.e. nitrogen content and total solubility of nitrocellulose. The powder factory is therefore compelled to limit the number of factors which can be varied to obtain the powder of required ballistic properties. 

The batching of nitrocellulose consists of weighing the guncotton and collodion cotton in a ratio which gives a mixture of suitable nitrogen content with the required total solubility. 

The nitrogen content and solubility of the nitrocellulose mixture must be maintained within the following limits according to its intended use (Table 177). 

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