Stoichiometrically balanced materials

When nitramine particles such as HMX or RDX particles are mixed with a doublebase propellant, nitramine composite-modified double-base propellants are formulated. Since HMX and RDX are stoichiometrically balanced materials, the use of these nitramine particles leads to a somewhat different mode of combustion as compared to AP-CMDB propellants. Since each nitramine particle can burn independently of the base matrix at the burning surface, a monopropellant flamelet is formed in the gas phase from each particle. The monopropellant flamelet diffuses into the reactive gas of the base matrix above the burning surface and a homogeneously mixed gas is formed. 

Table 9.3 shows the measured detonation velocities and densities of various types of energetic explosive materials based on the data in Refs. [9-11]. The detonation velocity at the CJ point is computed by means of Eq. (9.7). The detonation velocity increases with increasing density, as does the heat of explosion. Ammonium ni-trate(AN) is an oxidizer-rich material and its adiabatic flame temperature is low compared with that of other materials. Thus, the detonation velocity is low and hence the detonation pressure at the CJ point is low compared with that of other energetic materials. However, when AN particles are mixed with a fuel component, the detonation velocity increases. On the other hand, when HMX or RDX is mixed with a fuel component, the detonation velocity decreases because HMX and RDX are stoichiometrically balanced materials and the incorporation of fuel components decreases their adiabatic flame temperatures. 

Crystalline particles that produce gaseous oxidizer fragments are used as oxidizer components and hydrocarbon polymers that produce gaseous fuel fragments are used as fuel components. Mixtures of these crystalline particles and hydrocarbon polymers form energetic materials that are termed composite propellants . The oxidizer and fuel components produced at the burning surface of each component mix together to form a stoichiometrically balanced reactive gas in the gas phase. 

Nitramine composite propellants composed of HMX or RDX particles and polymeric materials offer the advantages of low flame temperature and low molecular mass combustion products, as well as reduced infrared emissions. The reduced infrared emissions result from the elimination of COj and H2O from the combustion products. To formulate these composite propellants, crystalline nitramine monopropellants such as HMX or RDX are mixed with a polymeric binder. Since both HMX and RDX are stoichiometrically balanced, the polymeric binder acts as a coolant, producing low-temperature, fuel-rich combustion products. This is in contrast to AP composite propellants, in which the binder surrounding the AP particles acts as a fuel to produce high-temperature combustion products. 

I(HMX). The base matrix of the double-base propellant is composed of NC and NG in the ratio of 0.2/0.8. Since HMX is a stoichiometrically balanced energetic material, it serves as an energetic material rather than as an oxidizer. Accordingly, the flame temperature increases monotonously as (HMX) is increased. 

Material Balance. Material balances for a low and high sulfur content gas to the RC/Bahco CTB-100 module are illustrated in Table IV. Operating data from actual installations indicate 93-99% SO2 removal and particulate emissions as low as 0.01 grain/SCFW. Scrubbing reagent consumption is about 1.1 times the stoichiometric amount. 

In the initiation part of free-radical chain reactions, a small amount of one of the stoichiometric starting materials (i.e., a starting material that is required to balance the equation) is converted into a free radical in one or more steps. An initiator is sometimes added to the reaction mixture to promote radical formation. In the example, though, no initiator is necessary light suffices to convert Br2, one of the stoichiometric starting materials, into a free radical by cr-bond homolysis. 

The yield of a reaction is the amount of product obtained. This value is nearly always less than what would be predicted from a stoichiometric balance because side-reactions may produce different products, the reverse reaction may occur, and some material may be lost during the procedure. The yield from a stoichiometric balance on the limiting reagent is called the theoretical yield. Percent yield is the actual yield divided by the theoretical yield ... 

This device is configured so that upon exposure to an acidic environment, an amount of the second biodegradable material degrades and releases the encapsulated buffering agent in an amount that provides a stoichiometric balance between the amount of buffering agent released and the total amount of acid released from the device, such that the pH level is raised to a neutral pH level (60). 

Stoichiometric balance n. Mass balance of materials (non-energy) involving reactions and conversions. 

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