Single-based propellants stabilizer

A II single base propellant stabilized with 0.9 % acardite II DPA single base propellant stabilized with 1.1 % diphenylamine C I single base propellant stabilized with 0.6 % centralite I... 

The review suggests that diphenylamine (DPA) is the most common stabilizer in single-based propellants, whereas ethylcentralite (EC) is the most common in double based. In fact, Table 21.1 and Table 21.2 show that DPA... 

At high temperature, nitrocellulose slowly decomposes, producing nitric oxide (NO) and nitrogen dioxide (NO2). The secondary reaction, such as the addition of NO2 to the other parts of the chain, can be prevented by adding stabilizers such as diphenylamine, nitrodipheny-lamine, ethylaniline, carbazole, and others [5, 6]. These stabilizers are generally present in quantities of less than 2 percent. Some examples of single-base propellants are given in Table 12.4. 

A method developed in 1927 by the Dutchman Thomas for the determination of the chemical stability of propellants. The parameter which is determined in the method is the weight loss which takes place after 72-hours heating at 105 °C (221 °F) (multibase propellants) or at 110 °C (230°F) (single-base propellants). This loss, after subtracting the loss occurring after the first 8 hours of heating, must not exceed 2%. 

Single base propellant consists mainly of cellulose nitrate and a stabilizer, and some single base propellants also contain small quantities of glycerol trinitrate. In addition, single base propellants may be surface treated with centralite I (diethyl diphenyl urea, ) dibutylph-thalate, camphor, dinitrotoluene and other phlegmatisers. 

Heat Tests. Heat tests are performed at 1 34.5°C for single-base propellants and 1 20°C for double-and triple-base propellants. These tests measure the stability of the propellant Specimens of the propellant are placed into the bottom five centimeters (two inches) of a glass test tube. A piece of methyl violet indicator paper is placed vertically in the tube so that the lower end of the paper is 25 millimeters from the specimen. The tube is corked and set into a constant temperature block or a constant temperature reflux bath. The temperature must be maintained to within 0.5°C. The result of the test is reported as the time required for the test paper to change color to salmon pink. For the propellant to pass the test, the color change cannot occur in less than 40 minutes or 60 minutes, depending on the propellant formulation, and the sample may not explode in less than five hours. 

This criterion is the so-called T combustion instability. The stability criterion expressed by < 1 is not sufficient to obtain stable combustion when the flame temperature is dependent on pressure.lO In general, m is approximately zero in the high-pressure region for most propellants. However, l/of nitropolymer propellants such as single-base and double-base propellants decreases with decreasing pressure below about 5 MPa. Since direct determination of m is difficult, the heat of explosion, is evaluated as a function of... 

Since the development of this terpolymer in 1957, more solid composite rocket propellant has been produced from PBAN than from any other single prepolymer. Propellants based on this material have been used successfully in applications ranging from small tactical motors to the 260-in. diameter motor containing greater than 2,000,000 lb. of propellant. PBAN propellants, therefore, have been and are expected to be a major factor in making solid rocket motors during the next several years. The thermal stability which has been achieved, low temperature cycling characteristics, and low cost of propellants based on this prepolymer make this system attractive. 

Table 4.8 Some stabilizers for single-base, double-base and triple-base propellants.

One of the older US mortar proplnts contained vaseline(petroleum jelly) which presumably acted as a stabilizer and flash-reducer. The compn of this proplnt was NC(13.15%N) 54, NG 43 vaseline 3%, with 0.5% DPhA added(US Spec 50-12-4A). Another older US cannon, proplnt contained TNT and hydrocellulose. Its compn was NC(12.6%N) 49, NG 20, TNT 20 hydrocellulose 10%. Here TNT was added for the same purpose as DNT(See under Single-Base Cannon Propellants). Hydrocellulose was used as flash-reducer. Its "cooling effect is due to development of large amts of gaseous products,... 

Heat Test minimum 30 mins Vapor Pressure at 60° O.OmmHg Volatility at 60° 0.0% and Water Produced on Explosion 140g/kg of NC Uses. Pyrocellulose has been used since the Spanish-American War(1898) in cannon and small arms proplnts. Historical development of "PyrpP proplnts is described under Cannon Propellants(qv). The original US single-base proplnts consisted of Pyrocellulose colloided with ether-ale, but beginning ca 1909, there was added 0.5% DPhA to act as a stabilizer and this amt was later incteased to 1%. This period also saw the introduction of the water-dry process which permitted manuf of proplnts in a fraction of the time reqd for the "air-dry process (Ref 44)... 

Diphenylamine is the most common stabilizer especially in single-based powders. It has been suggested that diphenylamine is not a good stabilizer for double-based propellants as it may hydrolyze NG.59 2-Nitrodi-phenylamine is used for double- and triple-based propellants. 

French gunpowder. A single base nitrocellulose propellant stabilized by 1.5-2% diphenylamine. The sufix (e.g., Poudre B Ba) denotes ... 

Use af Ethanol and Ether in the Manufacture af Single-Base Smokeless Propellant s. Operation s in manuf of single-base smokeless proplnts from Pyrocellulose, which is NC of N content 12.60-0.10% (described in Vol 2 of Encycl, p 003) are discussed in Vol 3 of Encycl, under "Colloiding Agents and Colloidal Propellants on pp C398 C399. Manuf of NC is described in Vol 2, p 002, while its stabilization for use in smokeless propellants is described in Vol 2, p 007... 

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