Propellant vulnerability

Nitramine-nitrates of general structure (133) are known as NENAs and are conveniently prepared from the nitrative cleavage of A-alkylaziridines " with dinitrogen pentoxide or from the direct nitration of the corresponding aminoalcohols. These compounds find use as energetic plastisizers in explosive and propellant formulations Bu-NENA (R = n-Bu) is a component of some LOVA (low vulnerability ammunition) propellants. ... 

The reaction of aziridines and azetidine heterocycles with dinitrogen pentoxide in chlorinated solvents yields 1,2-nitramine nitrates and 1,3-nitramine nitrates respectively. In most cases yields are good to excellent, but, reactions are not as general as with the oxygen heterocycles the outcome of reactions is heavily dependent on the nature of the substituent on the exocyclic nitrogen. Some of the products from these reactions find use as melt-castable explosives i.e. Tris-X (46) and energetic plasticizers e.g. Bu-NENA (48) the latter is a component of some LOVA (low vulnerability ammunition) propellant formulations. 

Most composite propellants in wide use today use ammonium perchlorate as the oxidizer component. While such propellants benefit from high specific impulse and a lower vulnerability than double-base propellants based on nitroglycerine, they have a significant environmental impact, the exhaust fumes being rich in corrosive hydrogen chloride leading to acid rain after the launch of missiles/rockets. 

These properties of FOX-7 and FOX-12 suggest that they are very promising candidates for IM and are likely replacement of RDX as warhead fillings. These explosives are also potential candidates for low-vulnerability ammunition (LOVA) propellants. It has been reported that FOX-12-based propellants are highly resistant to shaped charge attack. 

In order to reduce this risk, low vulnerability ammunition (popularly known by the acronym LOVA) propellants are attractive alternatives for conventional gun propellants. The incorporation of materials possessing higher ignition temperatures into propellant formulations while maintaining superior energetics, is key to the development of LOVA/insensitive propellants [17, 18]. This is usually done by a judicious combination of energetic oxidizers and suitable binders which are described in the subsequent paragraphs. 

Wise and Rocchio [32] have discussed the processing techniques for LOVA formulations which invariably depend on the type of binder. The polybutadiene-based formulations referred to as cured systems, are processed through a solventless process whereas formulations based on cellulose derivatives and thermoplastic elastomers as binders are processed by a solvent process similar to standard NC propellants. In conclusion, LOVA formulations offer unique propulsion systems for tanks with the potential to offer high energy and low vulnerability. 

In summary, HAN-based propellants are markedly superior to other liquid propellants and also appear to possess physical properties and a number of other characteristics necessary for their use in a practical gun. Their performance may be further enhanced by the use of some additives. These propellants are also biodegradable so that disposal is not a problem [40, 41]. The data generated as a result of extensive characterization and hazard testing indicate that HAN-based propellants are suitable for military use. The HAN-based liquid propellants also appear to offer low vulnerability characteristics comparable to the LOVA propellants [42-44]. 

The data reported in the literature suggests that the replacement of DEP by Bu-NENA in the Dense NC/NG+ DEP/AP/AI/RDX-based composite modified double-base (CMDB) propellants results in increase in the burn rate by 18-20% at 70 kg cm pressure. The calorimetric value and percentage elongation also increase significantly. Further, thermal stability and sensitivity of such propellants are comparable with DEP-based CMDB propellants [184]. Bu-NENA is also a component of low vulnerability ammunition (LOVA) propellants [185, 186]. The introduction of butyl-NENA into SB, DB and gun propellants results in improvement of their mechanical properties and energetics and reduction in their sensitivity [187]. 

Wise, S., and Rocchio, J.J. (1982) A development process for low vulnerable propellants. Proc. 13th Inti Jahrestagung, 1982, Karlsruhe, Germany, June 30-July 02,1982, pp. 539-544. 

Liquid gun propellant Lawrence Livermore National Laboratory Low vulnerability ammunibon Liquid oxygen... 

Solid propellant compositions which have been previously discussed all sulfer from the possibility of accidental initiation from fire, impact, electric spark, etc. Therefore, attention has turned to the development of insensitive munitions with particular emphasis on low vulnerability ammunition (LOVA). LOVA propellants contain RDX or HMX, an inert polymeric binder and a plasticizer. These composite propellants are less vulnerable to initiation than nitrocellulose-based propellants. 

Gun propellants usually are single base (NC), double base (NC and NG), or triple base (NC, NG, and nitroguanidine (NQ)). Some of the newer, lower vulnerability gun propellants contain binders and crystalline explosives and thus are similar to PBX. 

Since 1970, in addition to the various well-known -> Gun Powders, LOVA gun propellants have been developed and used in the production of propellants. The acronym LOVA stands for (LOw Vulnerability Ammunition) which has come to represent a type of gun propellant. 

An abbreviation for low-vulnerability ammunition. This term is descriptive of the trend towards choosing substances for both explosive and propellant charges which are as intensive as possible even if losses in effectivity have to be accepted. The development of -> Shaped Charges has made it possible to hit stored ammunition with simple tactical weapons even behind armoured walls. 

For propellant charges the insensitivity is also playing an increasingly important role. Since approximately 1970 propellant charges have been developed and used under the title LOVA (low-vulnerability ammunition). Under bullet impact, shaped charge impact or fire they respond with fire in the worst case scenario, but not in deflagration and definitely not in detonation. As energetic fillers mainly RDX... 

The oldest of the composite propellants is black powder that is produced by mixing the ingredients wet and then wheel-milling them. The tremendous pressures in the mill cause the sulfur to plasticize and flow. The product is then treated, dried, and screened to produce the various grades as a function of the particle sizes. The composite propellants are less vulnerable to initiate than nitrocellulose-base propellants [5]. 

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