Burning rate nitroglycerine

Steinberger and Carderl24.25] measured the burning rates of liquid strands composed of 63 % nitroglycerin and 37 % diethylene glycol. When 5 % lead aspirate was added to the basic liquid strand, they observed an increased burning rate between 4.0 MPa and 13.5 MPa. This effect is qualitatively the same as in the case of a double-base propellant. The burning rate of the liquid strand was increased by 70 % at 6.8 MPa by the addition of the lead aspirate. 

Since the energy contained within double-base propellants is limited because of the limited energies of nitrocellulose (NC) and nitroglycerin (NG), the addition of ammonium perchlorate or energetic nitramine particles such as HMX and RDX increases the combustion temperature and specific impulse. Extensive experimental studies have been carried out on the combustion characteristics of composite-modified double-base (CMDB) propellants containing AP, RDX or HMX parhclesli- l and several models have been proposed to describe the burning rates of these pro-... 

These propellants are also called colloidal or double-base (DB) propellants and have nitrocellulose (NC) and nitroglycerine (NG) as their principal ingredients. Some ingredients may also be added in small proportions to serve as stabilizer, non-explosive plasticizer, coolant, lubricant, opacifier and burning-rate modifier or other additives to impart desirable properties to the propellants. These propellants are processed into desired shapes by two methods, that is, extrusion and casting. They find wide applications in anti-tank missiles. 

Fig. 14. Rate of burning of nitroglycerine as a function of pressure (Andreyev [60, 61]).

Nitroglycerine burns readily in open vessels under atmospheric pressure. When confined it burns more readily under reduced pressure, for e.Kample 0.5 attn. When confined in a tube nitroglycerine burns under atmospheric pressure it the diameter is larger than 0.5 mm. The rate of burning at the critical diameter of 0.5 cm is 0.14 cm/sec. [60]. Andreev and Bezpalov (84) indicated that the critical diameter of burning of nitroglycerine under pressure within the range 20 100 atm is still reduced. They pointed out that three diameters exist ... 

Gunpowder (nitrocellulose + nitroglycerine) with stabilizers such as diphenylamine and diethyldiphenylurea, burning rate modifiers and coolants such as potassium nitrate, potassium sulfate, barium nitrate, or dinitrotoluene. 

According to a, pj, and <5 values from experiments, the calculated mass burning rates of methyl nitrite, diethyleneglycol dinitrate, and nitroglycerine in one standard atmosphere press are 0.25, 0.26, and 0.25 g/cm s, separately. It is concluded that the right side of Eq. 2.19 is approximated as a constant. If the pressure is 1 atm, it is 0.25 g/cm s. When the burning rate is over 0.25 g/cm s, detonation of liquid explosives is possible. 

J. Taylor [27] drew up the following table of the heat of explosive decomposition, the gas volume and rate of burning of British nitroglycerine (double base) and American nitrocellulose (single base) powders (Table 166). 

To obtain ballistite with a more progressive rate of burning, attempts were made to produce laminated flakes, with the two outer layers made of attenuated ballistite and an inner one, sandwiched between, made of ordinary ballistite. In the attenuated ballistite DNT was substituted for part of the nitroglycerine. However a powder of this type retained its ballistic characteristics for only a few months, since, due to diffusion, the composition of all three layers gradually became equal. 

Generalizing, Andreyev reported that nitroglycerine bums steadily at pressures below 400 mm Hg the rate of burning depends on the pressure (Fig. 14) according to the equation ... 

Solid propellants may be classified as monopropellants or composite propellants. Monopropellants are substances in which the fuel and oxidizer are both contained within the same molecule or at least in a single phase. These materials may either burn slowly at subsonic rates or may decompose rapidly in detonation. Depending on the use to which this type of material is put, it may be classified either as propellant or high explosive. In general, useful monopropellants are difficult to detonate. The typical example of a monopropellant is the so-called double-base propellant. This substance consists of nitrocellulose which has been colloidized by nitroglycerine along with various minor constituents which have been added to... 

Explosive material with low rate of combustion. May be either solid or liquid. Will burn smoothly at uniform rate after ignition without depending on interaction with atmosphere. Single base propellant consists primarily of matrix of nitrocellulose. Double base propellant contains nitrocellulose and nitroglycerine. Composite propellant contains oxidizing agent in matrix of binder. 

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