Scavenged propellant

Thus, the number of HCI molecules is reduced when sodium nitrate particles are incorporated into AP propellants. This class of propellants is termed scavenged propellants . Fig. 12.18 shows the results of thermal equibbrium computations of scavenged AP propellants as a function of the mass fraction of sodium nitrate. 

Sodium nitrate has recently become of interest as a co-oxidizer for scavenger propellants. These propellants contain sufficient alkali metal (sodium) in the formulation to react with the chloride generated during combustion of the major oxidizer, ammonium perchlorate. Sodium chloride, rather than hydrochloric acid, is produced in the exhaust stream as the final chlorine-containing reaction product. The benefit of scavenging the chloride ion is lowered exhaust toxicity however, a substantial loss of propellant impulse results. 

Main uses. Caesium metal is used in the production of vacuum tubes as a scavenger to reduce residual gaseous impurities after the tubes have been sealed. Cs may be generated in situ by heating a pellet of caesium chromate mixed with a metal powder (Zr, Ca, Ba). Cs metal is used as the propellant in ion thrusters (employed in satellites for orientation control) it is ionized in a vacuum chamber, the Cs+ are then accelerated through a nozzle (high specific impulse because of high atomic mass). 

Fig. 12.18 Mole fractions of HCI and NaCI produced by scavenged AP propellants as a function of (NaNOj).

Fig. 12.20 Specific impulses of scavenged and neutralized AP composite propellants as a function of KNaNO,) or (Mg)...

Stabilizers are necessary because nitrocellulose decomposes with age. The decomposition reaction yields dinitrogen tetraoxide which acts as an autocatalyst and accelerates the decomposition.58 Stabilizers act as dinitrogen tetraoxide scavengers consequently shelf life is increased. Stabilizers are normally added in the region of 0.5 to 2.0%. To neutralize the decomposition products, which could cause corrosion of the firearm, calcium carbonate is added to some propellants. A common stabilizer is diphenylamine or its nitro derivatives (Figure 10.2). 

Potlife and Cure. In addition to achieving a castable viscosity, it is necessary that the liquid (uncured) propellant remain fluid for a sufficient amount of time to be transported, cast, and cleaned up, with allowance for possible delays, before it solidifies appreciably. Following cast, the composition must be cured to a solid, preferably at temperatures close to the intended storage temperature. The balancing of potlife and cure rate frequently requires careful adjustment of cure catalyst levels, catalyst scavengers, mix temperature, and cure temperature. 

Use Special-purpose alloys, cementation of iron, neutron absorber in reactor controls, oxygen scavenger for copper and other metals, fibers and filaments in composites with metals or ceramics, semiconductors, boron-coated tungsten wires, rocket propellant... 

The mapping shown in Fig. 1 includes references to SBR and styrene block copolymers in the PB search. Removing these citations from the database reduced the number to 4297, which can be seen mapped in Fig. 3. the area of high activity is centered on hydroxy terminated PB (HTPB). Low-Mn HTPB can be prepared by a variety of polymerization processes such as radical, anionic, or even using acyclic diene metathesis (ADMET).f The HTPB has a variety of uses as a propellant. " Other uses include reaction with epoxy resins, nylon, urethane, or even in the formulation of adhesives.t" The use of HTPB as an oxygen scavenger in polyamide, polyvinyl alcohol, and multilayer... 

Boron Boron, metallic EINECS 231-151-2 HSDB 4482. Nonmetallic element. Used in special-purpose alloys cementation of iron neutron absorber in reactor controls oxygen scavenger for copper and other metals fibers and filaments in composites semiconductors rocket propellant mixtures, mp = 2200" insoluble in H2O. Atomergic Chemetals Noah Chem. 

EINECS 231-102-5 HSDB 647 Lithium Lithium, elemental Lithium, metallic UNI 415, Metallic element. Used as a scavenger and degasifier for stainless and mild steels in molten state deoxidizer in copper and alloys rocket propellants pharmaceuticals. Brittle metal mp = 180.54° bp = 1347° reacts violently with inorganic acids soluble in liquid ammonia does not react with oxygen at room temperature. Atomergic Chemetals Cerac FMC... 

Uses Reducing agent corrosion inhibitor wastewater treatment electrolytic plating redox reactions polymerization catalyst organic hydrazine derivs. rocket propellant corrosion inhibitor, oxygen scavenger in boiler... 

The uses of inorganic derivatives of hydrazine as explosives and propellants (energetic materials), oxygen scavenger (boiler water treatment) and analytical reagents, and so on, although known, are not well documented. Some of these applications are discussed in this chapter. 

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