Composite burn-rate modifiers

Bfx, Fx, and related compoimds are the subject of a great munber of invention patents especially related to its uses in material sciences. For example, they were included in the formiflation as rubber additives [245,246], as inhibitors in the polymerization of aromatic vinyl monomers [247], as components in the igniting composition for inflation of airbags [248,249], as explosives [250-253], as soHd propellants [254], as burn-rate modifiers [255], and as liquid-crystalHne materials [256]. 

As in the case of double-base propellants, various types of materials, such as plasticizers, burning rate modifiers, and combustion instability suppressants, are added to mixtures of AP and a binder. Table 4.12 shows the materials used to formulate AP composite propellants. 

Pyrodex" is a patented pyrotechnic composition designed to fulfill many of the funetions of blaek powder. It eontains the three ingredients found in blaek powder plus binders and burning rate modifiers that make the material somewhat less sensitive and slower burning. A greater degree of confinement is required to obtain performance comparable to "normal" black powder [6]. 

Basically, PVC plastisol propellants are systems of binder,.oxidizer, and metallic fuel (if used). Minor ingredients, normally comprising less than 2% of the total, consist of wetting agent, stabilizer, opacifier, and burning rate modifier. The composition of three typical PVC plastisol propellants is shown in Table I. 

Table 4.14 Burn-rate modifiers for composite propellants. ...

NTO is being developed in many areas these include i) a substitute for ammonium perchlorate or ammonium nitrate in solid rocket propellants, since it does not liberate undesirable products such as HC1 and has quite a high burn rate compared to ammonium perchlorate and ammonium nitrate, ii) used as a burning rate modifier for composite propellants, iii) replacing RDX and HMX in composite solid propel-... 

The role of the heat of expln of gun propints on bore wear was discussed in Vol 8, P405-R. Exhaust gas compns of composite propints were tablulated in Vol 8, P41Q-L, the heats of expln for double base, NC based and composite propints was listed in Vol 8, P 408-L to P418-R The role of burning rate modifiers is described in Vol 8. P430-L to P439-L 8.3 Pyrotechnic Compositions... 

Long-burning formulations for infrared tracking flares typically comprise burn rate modifiers that extend the burning time. For this purpose, barium stearate has been proposed. Figure 10.20 shows the effect of stearate content on both normalized burn rate and spectral efficiency. Whereas the burn rate drops to levels of 20% of the unaffected composition shown below, the spectral efficiency climbs up to levels of 140% [28]. 

Composition C-4 (RDX + polyisobutylene + motor oil + di-(2-ethylhexyl) sebacate) Gunpowder (nitrocellulose + nitroglycerine) with stabilizers such as diphenylamine and diethyldiphenylurea, burning rate modifiers and coolants such as potassium nitrate, potassium sulfate, barium nitrate, or dinitrotoluene HMX (High Melting Explosive)... 

Since the energetics of nitropolymer propellants composed of NC-NG or NC-TMETN are limited due to the limited concentration of oxidizer fragments, some crystalline particles are mixed within these propellants in order to increase the thermodynamic energy or specific impulse. The resulting class of propellants is termed composite-modified double-base (CMDB) propellants . The physicochemical properhes of CMDB propellants are intermediate between those of composite and double-base propellants, and these systems are widely used because of their great potential to produce a high specific impulse and their flexibility of burning rate. 

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-... 

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]. 

Two-way analysis of variance (and higher classifications) leads to the presence of interactions. If, for example, an additive A is added to a lube oil stock to improve its resistance to oxidation and another additive, B, is added to inhibit corrosion by the stock under load or stress, it is entirely possible that the performance of the lube oil in a standard ball-and-socket wear test will be different from that expected if only one additive has present. In other words, the presence of one additive may adversely or helpfully affect the action of the other additive in modifying the properties of the lube oil. The same phenomenon is clearly evident in a composite rocket propellant where the catalyst effect on burning rate of the propellant drastically depends on the influence of fine oxidizer particles. These are termed antagonistic and synergistic effects, respectively. It is important to consider the presence of such interactions in any treatment of multiply classified data. To do this, the two-way analysis of variance table is set up as shown in Table 1.24. 

Charcoal is used for many purposes e,g. to obtain an explosive force as a fuel producing a large amount of heat and gas in combination with an oxidizer to adjust the burning rate of compositions to obtain sparks or fire dust to modify the ignition character of compositions to increase brightness of.flames or simply as a combustion agent which helps the burning of compositions. 

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