Nitramine-CMDB Propellants

AP-CMDB propellants bum with a different mode from that of nitramine-CMDB propellants, namely that of AP composite propellants, a diffusion-flame mode. On the other hand, nitramine-CMDB propellants bum with a mode of double-base pro-... 

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. 

Triple-base propellants are made by the addition of crystalUne nitroguanidine (NQ) to double-base propellants, similar to the way in which nitramine is added to CMDB propellants as described in the preceding section. Since NQ has a relatively high mole fraction of hydrogen within its molecular structure, the molecular mass of the combustion products becomes low even though the flame temperature is reduced. Table 4.13 shows the chemical composition, adiabatic flame temperature, and thermodynamic energy,/ as defined in Eq. (1.84), of a triple-base propellant at 10 MPa (NC 12.6% N). 

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-... 

A study was conducted to find out the effect of addition of these nitroplasticizers on ballistic properties of AP and RDX/HMX filled CMDB propellants. The data generated clearly indicated that the incorporation of nitroplasticizer, that is, 1 1 mixture of BDNPF and BDNPA in place of diethyl phthalate (DEP) for AP and nitramine based CMDB propellants improved the burn rates as well as /sp and thermal decomposition behavior of these propellant formulations [193]. 

Typical crystalline-energetic-particles are AP and nitramines such as HMX and RDX. The use of AP leads to an AP-CMDB propellant and the use of HMX leads to an HMX-CMDB propellant. These particles burn as a monopropellant at the burning surface of the CMDB propellant, and the combustion products react again with the combustion products of the base matrix. 

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