Booster explosives are those components of the explosive train that function to transmit and augment the force and flame from the initiating explosive. They ensure the reliable detonation or burning of the main burster charge or propellant charge. Propelling charges use a black powder booster, while high-explosive boosters use one of the following: Tetryl, CH-6, or Composition A-5.
Tetryl is a nitramine booster explosive, though the use has been largely superseded by RDX. Tetryl is sensitive secondary high explosive used as a booster, a small charge placed next to the detonator in order to propagate the detonation into the main charge. While it is commonly known as Tetryl it is in fact Trinitrophenylmethylnitramine (derivative of Benzene). This is a standard booster explosive. Tetryl is a fine yellow crystalline material. When tetryl is heated, it first melts, then decomposes and explodes. It burns readily and is more easily detonated than explosive D.
It is a yellow crystalline solid powder material, practically insoluble in water but soluble in Acetone, Benzene and other solvents. It burns readily and is more easily detonated than TNT or Ammonium Picrate (Explosive D), being about as sensitive as Picric Acid. It is detonated by friction, shock, or spark . It remains stable at all temperatures which may be encountered in storage. It is generally used in the form of pressed pellets, and has been approved as the standard bursting charge for small-caliber projectiles, since it gives much better fragmentation than TNT. It also has greater shattering ability than any other military high explosive, and must be properly protected from bullet fire . Its rate of detonation is 23,600-23,900 feet per second. Tetryl is the basis for the service Tetryl blasting caps necessary for positive detonation of TNT. A mixture of Fulminate of Mercury and Potassium Chlorate is included in the cap to insure detonation of Tetryl.
The most toxic ordnance compounds, tetryl and 1,3,5-TNB, are also the most degradable. Therefore these chemicals are expected to be short-lived in nature, and environmental impacts would not be expected in areas that are not currently subject to chronic inputs of these chemicals. Tetryl decomposes rapidly in methanol/water solutions, as well as with heat. All aqueous samples expected to contain tetryl should be diluted with acetonitrile prior to filtration and acidified to pH <3. All samples expected to contain tetryl should not be exposed to temperatures above room temperature. In addition, degradation products of tetryl appear as a shoulder on the 2,4,6-TNT peak. Peak heights rather than peak areas should be used when tetryl is present in concentrations that are significant relative to the concentration of 2,4,6-TNT.
CH-6 is a mixture of 97.5% RDX (described in the next section), 1.5% calcium stearate, 0.5% polyisobutylene, and 0.5% graphite. It is a finely divided gray powder that is less toxic and more available than tetryl.
Composition A-5 is a mixture of 98.5% RDX and 1.5% stearic acid.
NQ [Nitroguanidine / Picrate]
Ammonium Picrate (Yellow D / Explosive D), or Picric Acid or 2,4,6-trinitrophenol, C6H2(NO2)3OH, a toxic yellow crystalline solid that melts at 122°C and is soluble in most organic solvents. Picric acid is a derivative of phenol. It reacts with metals to form metal picrates, which like picric acid itself are highly sensitive explosives that can be detonated by heat, flame, shock, or friction.
The high explosives lyddite and melinite are composed mostly of compressed or fused picric acid. Picric acid is often used as a booster to detonate another, less sensitive explosive, such as TNT (trinitrotoluene ). Although picric acid, a nitramine explosive, can be synthesized by nitration of phenol, higher yields are obtained if chlorobenzene is used as a starting material; the latter method involves several steps and the formation of several intermediate products. In addition to its use in explosives, picric acid has been used as a yellow dye, as an antiseptic, and in the synthesis of chloropicrin, or nitrotrichloromethane, CCl 3 NO 2 , a powerful insecticide.
A UXO item without a fuze is relatively safe (crystallized bulk explosives, picrate salts, chemical, and white phosphorous rounds excepted).
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