Double-base matrix

On addition of AP particles to a double-base matrix, very fine luminous flamelet-sare formed from each AP particle at the burning surface, which diffuse into the dark zone of the base matrix. As the number of AP particles added to the base matrix is increased, the number of flamelets also increases and the dark zone is replaced with a luminous flame. 

When large spherical AP particles dg = 3 mm) are added, large flamelets are formed in the dark zone.Pl Close inspection of the AP particles at the burning surface reveals that a transparent bluish flame of low luminosity is formed above each AP particle. These are ammonia/perchloric acid flames, the products of which are oxidizer-rich, as are also observed for AP composite propellants at low pressures, as shown in Fig. 7.5. The bluish flame is generated a short distance from the AP particle and has a temperature of up to 1300 K. Surrounding the bluish flame, a yellowish luminous flame stream is formed. This yellowish flame is produced by in-terdiffusion of the gaseous decomposition products of the AP and the double-base matrix. Since the decomposition gas of the base matrix is fuel-rich and the temperature in the dark zone is about 1500 K, the interdiffusion of the products of the AP and the matrix shifts the relative amounts towards the stoichiometric ratio, resulting in increased reaction rate and flame temperature. The flame structure of an AP-CMDB propellant is illustrated in Fig. 8.1. 

When the states P1 and P2 are described as linear combinations of CSFs as introduced earlier ( Fi = Zk CiKK), these matrix elements can be expressed in terms of CSF-based matrix elements < K I eri IOl >. The fact that the electric dipole operator is a one-electron operator, in combination with the SC rules, guarantees that only states for which the dominant determinants differ by at most a single spin-orbital (i.e., those which are "singly excited") can be connected via electric dipole transitions through first order (i.e., in a one-photon transition to which the < Fi Ii eri F2 > matrix elements pertain). It is for this reason that light with energy adequate to ionize or excite deep core electrons in atoms or molecules usually causes such ionization or excitation rather than double ionization or excitation of valence-level electrons the latter are two-electron events. 

There is also an as-yet small but growing class of formulations known as PBX Plastic Bonded Explosive. PBXs are similar to rubber-base, composite rocket proplnts in that they consist of 85% or so of powdered high-energy explosive incorporated into a plastic matrix (which can be a conventional plastic or a double-base) and cast into place. 

A third type of propellant, the composite modified-double-base propellant, represents a combination of the other two types. These propellants are made from mixtures of nitroglycerine and nitrocellulose or similar materials, but with crystalline oxidizers such as ammonium perchlorate also included in the matrix. 

Though the physical structures of CMDB propellants are heterogeneous, similar to those of composite propellants, the base matrix used as a binder burns by itself and the combushon mode of CMDB propellants appears to be different from that of composite propellants and double-base propellants. The burning rate ofa CMDB propellant is dependent on the type of crystalline parhcles incorporated. 

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. 

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. 

Experimental observation indicates that the AP particles within the matrix of a double-base (DB) propellant appear to burn and regress in size spherically on the burning surface. Thus, the regression rate of the particles appears to depend on their instantaneous diameter. The average burning rate of each AP particle is determined as a function of pressure, as shown in Fig. 8.3. The burning rate is represented by r p = where Kj is independent of pressure, r p is the burning rate... 

The temperature sensitivity, o, as defined in Eq. (3.73), of the HMX-CMDB propellants is shown as a function of hmx in Fig. 8.17. Though of the double-base propellant used as the base matrix decreases with increasing pressure, the values of the HMX-CMDB propellants remain relatively constant when hmx is kept con-... 

Since the burning surface becomes highly heterogeneous with increasing hmx the determination of values is no longer possible, which precludes the determination of the heat of reaction at the burning surface, Q. However, it is assumed that the decomposition of the HMX particles within the base matrix occurs relatively independently of the decomposition of the base matrix, i. e., the double-base propellant. The overall heat release at the burning surface of an HMX-CMDB propellant is thus represented by[i]... 

EJ (Propellants). American sol vent-extruded propellants developed during WWII at the Allegheny Ballistics Laboratory and at the Radford Development Department of the Hercules Powder Co. They oontd K oer-chlorate-carbon black filler in a double-base propint matrix... 

EJB was a modification of EJA in which filler (KC104 + C hlack) was reduced from 65% to 30%, making its compn KC10 4 26 C black 4% in a double-base propint matrix. 

Explosive material with low rate of combustion. May be either solid or liquid. Will burn smoothly at uniform rate after ignition without depending on interaction with atmosphere. Single base propellant consists primarily of matrix of nitrocellulose. Double base propellant contains nitrocellulose and nitroglycerine. Composite propellant contains oxidizing agent in matrix of binder. 

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