Ammonium perchlorate properties

Oxidizers. The characteristics of the oxidizer affect the baUistic and mechanical properties of a composite propellant as well as the processibihty. Oxidizers are selected to provide the best combination of available oxygen, high density, low heat of formation, and maximum gas volume in reaction with binders. Increases in oxidizer content increase the density, the adiabatic flame temperature, and the specific impulse of a propellant up to a maximum. The most commonly used inorganic oxidizer in both composite and nitroceUulose-based rocket propellant is ammonium perchlorate. The primary combustion products of an ammonium perchlorate propellant and a polymeric binder containing C, H, and O are CO2, H2, O2, and HCl. Ammonium nitrate has been used in slow burning propellants, and where a smokeless exhaust is requited. Nitramines such as RDX and HMX have also been used where maximum energy is essential. 

The most outstanding property of the perchlorates is their oxidising abiUty. On heating, these compounds decompose into chlorine, chlorides, and oxygen gas. Aqueous perchlorate solutions exhibit Httle or no oxidising power when dilute or cold. However, hot concentrated perchloric acid is a powerful oxidizer and whenever it contacts oxidizable matter extreme caution is required. The acidified concentrated solutions of perchlorate salts must also be handled with caution. Ammonium perchlorate [7790-98-9] (AP) is one of the most important perchlorates owing to its high (54.5%) O2 content and the... 

Varying the semiconducting properties of the catalyst crystal affects the rate of ammonium perchlorate decomposition. 

Ammonium perchlorate has, in addition to the properties mentioned for the previous compounds, a specific instability due to its unfavourable oxygen balance. Friction is enough to make it detonate. Combined with aluminium it has been used as a propellant for rockets. In the presence of carbon and metal salts, it reacts exothermically below 240°C and detonates above this temperature. 

It is possible in both the above processes to add oxidisers such as ammonium perchlorate so as to give propellants which combine the properties of the composite propellants and the more conventional double base type. It is claimed that the product can have an ultimate tensile strength of 800 kPa with an elongation of roughly 30%. These properties must, however, be sacrificed to some extent if the highest propellent performance is required. 

Under severe initiation conditions, ammonium perchlorate can be made to explode by itself [10]. Mixtures of ammonium perchlorate with sulfur and antimony sulfide are reported to be considerably more shock sensitive than comparable KCIO 3 compositions [2]. Ammonium perchlorate can be used to produce excellent colors, with little solid residue, but care must be exercised at all times with this oxidizer. The explosive properties of this material suggest that minimum amounts of bulk composition should be prepared at one time, and large quantities should not be stored at manufacturing sites. 

The composite explosives are usually those consisting of powdered mixtures of an oxidizer and an organic fuel. Dynamites are composite expls contg some NG. The composite expls examined by Gordon consisted of AN-fuel or Ammonium Perchlorate-fuel and their properties were compared with those of TNT, RRX and pure Amm Perchlorate... 

Curing Agents for Carboxyl-Terminated Polybutadiene Prepolymers. The types of curing agents used to prepare binders for CTPB propellants are the same as those for PBAN or PBAA. The bifunctionality of CTPB, however, requires that part of the curing agents be polyfunctional to provide for the formation of the tridimensional network. Almost without exception, the polyfunctional aziridines and epoxides used with CTPB undergo side reactions in the presence of ammonium perchlorate, which affects the binder network formation. Kinetic studies conducted with model compounds have established the nature and extent of the cure interference by these side reactions. The types and properties of some of the crosslinkers and chain extenders used to prepare solid propellants are summarized in Table IV. 

Effects of Curing Agent Type. Epoxide-Cured Propellant. Carboxyl-terminated polybutadiene is a linear, difunctional molecule that requires the use of a polyfunctional crosslinker to achieve a gel. The crosslinkers used in most epoxide-cured propellants are summarized in Table IV and consist of Epon X-801, ERLA-0510, or Epotuf. DER-332, a high-purity diepoxide that exhibits a minimum of side reactions in the presence of the ammonium perchlorate oxidizer, can be used to provide chain extension for further modification of the mechanical properties. A typical study to adjust and optimize the crosslinker level and compensate for side reactions and achieve the best balance of uniaxial tensile properties for a CTPB propellant is shown in Table V. These results are characteristic of epoxide-cured propellants at this solids level and show the effects of curing agent type and plasticizer level on the mechanical properties of propellants. 

Some of the unusual properties of a solid propellant results from its basic composition. The two general categories of double-base and composite rubber binder propellants have many subcategories, but no exhaustive compilation will be attempted here. Most modem propellants consist of a deformable binder phase and a crystalline salt filler, such as ammonium perchlorate and usually a powdered metallic fuel such as aluminum. Table I gives some typical compositions for both composite rubber-based and composite double-base systems. 

The most important attributes of this invention are high impulse performance coupled with high exit temperature on primary combustion and favorable boron species in the primary motor exhaust. The system is also insensitive to impact and possesses excellent thermal stability at elevated temperatures. Additionally, the system is readily castable since the addition of solid oxidizers is not required. Further, high flexibility in the ballistic properties of the gas generator can be achieved by the addition of solid oxidizers such as ammonium nitrate, ammonium perchlorate, hydroxylammonium perchlorate, potassium perchlorate, lithium perchlorate, calcium nitrate, barium perchlorate, RDX, HMX etc. The oxidizers are preferably powdered to a particle size of about 10 to 350 microns [13]. 

Some technological information on the Aerojet General Corporation s composite propellants technology was published recently [20]. Ammonium perchlorate is ground to the particle sizes ranging from 1 to 200 fx and then mixed to form a blend of the various particle sizes which gives the best mechanical and ballistic properties. Ammonium perchlorate is mixed with liquid polybutadiene-acrylonitrile fuel, liquid plasticizer and aluminium powder (Fig. 118). The motor casing is coated internally... 

Composite rocket propellants are two-phase mixtures comprising a crystalline oxidizer in a polymeric fuel/binder matrix. The oxidizer is a finely-dispersed powder of ammonium perchlorate which is suspended in a fuel. The fuel is a plasticized polymeric material which may have rubbery properties (i.e. hydroxy-terminated polybutadiene crosslinked with a diisocyanate) or plastic properties (i.e. polycaprolactone). Composite rocket propellants can be either extruded or cast depending on the type of fuel employed. For composite propellants which are plastic in nature, the technique of extrusion is employed, whereas for composite propellants which are rubbery, cast or extruded techniques are used. 

The explosive salts of perchloric acid are considerably more interesting than the explosive chlorates, since these are more stable and safer to handle. A few of them, for instance ammonium perchlorate, rank as components of explosive mixtures and rocket propellants. Some salts of perchloric acid possess initiating properties (Vol. III). 

The explosive properties of ammonium perchlorate are more marked than those of ammonium nitrate. 

The compound was examined as a propellant explosive, it proved easily detonable and more sensitive than ammonium perchlorate. A formulation with hydroxyl terminated polybutadiene binder ignited spontaneously at room temperature [1]. Other workers have found it more tractable [2]. Detailed study of properties has been made. It is too friction sensitive for safe transport [3]. 

In a study of ballistic properties of a three-modal composite rocket propellant, the effect of coarse, medium and fine fractions of ammonium perchlorate on burning rate at 70 bar and 25 °C has been mathematically modeled. Limitations were imposed on the ratios of all three granulations of ammonium perchlorate xrfine fraction AP-7 pm=0.3-0.7 x2-coarse fraction AP-400 pm=0.0-0.40 x3-medium fraction AP-200 pm=0.30-0.70. 

Properties On ignition, reaction between zinc dust and hexachlorethane produces zinc chloride and free carbon, both of which pass off in the smoke. The ammonium perchlorate keeps the reaction going, ammonium chloride readily volatilizes and controls the rate of burning, and calcium carbonate stabilizes the mixture by taking up any hydrochloric acid which may be present. The smoke is harmless. 

ADNBF forms white to yellowish crystals, which decompose when heated to 270 Celsius. It may be used in explosives compositions, but its primary use is in solid rocket propellants, where it exhibits exceptional combustion properties equal to, or superior to ammonium perchlorate. ADNBF can be alloyed with TNT, RDX, or other high-energy secondary explosives for use in military or commercial blasting compositions. ADNBF also shows interests in pyrotechnic compositions, and in primary explosive compositions for use in blasting caps. ... 

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