Density of TNT

The enthalpy ol formation of trinitrotoluene (TNT) is —67 kj-mol", and the density of TNT is 1.65 g-cm-3. In principle, it could be used as a rocker fuel, with the gases resulting from its decomposition streaming out of the rocket to give the required thrust. In practice, of course, it would be extremely dangerous as a fuel because it is sensitive to shock. Explore its potential as a rocket fuel by calculating its enthalpy density (enthalpy released per liter) for the reaction... 

Density of TNT receptor Thickness of steel, mm Delay of deton, psecs... 

Most striking feature is the difference in behavior toward a change in the initial density pQ. Increase in density of TNT, RDX or Amm Perchlorate causes continuous increase in detonation velocity D, while for composite expls increase of D follows increase in density only to some limiting value and then D sharply decreases. This unusual behavior of composite expls is caused, accdg to Cook (Ref 2, pp 140-41), by slowing down of the diffusion reaction between fuel and oxidizer with increase in density... 

Miaud (Ref 4) devised a rapid method for detn of TNT in amatols by comparing density f of its benzolic soln with a table giving relation between densities of TNT in C4 H6 and % TNT in C4H ... 

As indicated in Vol 4, D394-L, the detonation velocity of TNT increases from 6025 to 6440 m/sec as the density increases from 1.30 to 1.50g/cm3. A straight-hne relationship has been demonstrated (Ref 150). The detonation temp also increases with density (Vol 4 D492-L). Both of these parameters are discussed in more recent papers (Refs 159 167). The critical impact energy and critical impact velocity have also been determined as functions of the density of TNT (Ref 150)... 

Specific gravity and density of loading. The specific gravity of solid a- trinitro toluene is 1.654-1.663 according to various authors, while that of the molten product is 1.467 at 82°C. The density of TNT, compressed under pressures vaiying from 1450 to 4350 kg/cm2, is 1.54-1.62 g/cm3 (Kast [57] 1907). 

The density of TNT varies directly with the pressure applied. The following table shows the density at various pressures (17) ... 

At ordinary temperatures TNT is essentiaiiy nonvoiatiie. TNT has a crystai density of 1.654 grams per cubic centimeter, a cast density of 1.5 to 1.6 grams per cubic centimeter and a maximum pressed density of 1.63 to 1.64 grams per cubic centimeter. Tabie 8-47 shows the density of TNT as a function of ioading pressure aithough densities as high as 1.64 grams per cubic centimeter have been reported. 

When used in blasting, ammonium nitrate is mixed with fuel oil and sometimes sensitizers such as powdered aluminum. Lower density ammonium nitrate is preferred for explosive formulation, because it absorbs the oil more effectively. When detonated,these mixtures have an explosive power of 40 to 50% that of TNT (see Explosives and propellants). 

For example, TNT shrinks from 11 to 12% on solidification, so that if the melt is too viscous during pouring, the entrapped air may not escape prior to solidification. These bubbles are further enlarged by the volume shrinkage of TNT, resulting in a porous cast of low density... 

A linear relationship between Chapman-Jouguet pressure and density was confirmed for Cyclotol and Octol (Ref 28). Despite the near-equal performance of RDX and HMX at equal densities there appears to be no economical way of making the density of RDX equal to the cast density of HMX. Dinitrobenzene (DNB) has been evaluated as an economical or emergency substitute for TNT but charges prepared with DNB gave somewhat poorer performance than... 

Fig 1 (presented by Cook in Ref 3 for TNT at a bulk density of about 1 g/cc) shows that at a given diameter the detonation velocity, D, decreases as Rg increases. Note, however, that... 

Fig 2. Critical diameter of TNT as a function of initial density. 1. Pressed or powder after Andreev and Belyaev (1960) (Ref 6). 

The cast density of Pentolites does not vary appreciably with blend compn. 50/50 Pentolite (hereafter to be referred to simply as Pentolite) has a cast density of 1.63—1,67g/cc (Ref 8a), while 10/90 Pentolite has a cast density of 1.60 g/cc (Ref 12). The density of pressed Pentolite lies between 1.60 and 1,65g/cc. Since Pentolites are blends (no compound formation) they are soluble in the same solvents as their constituents (PETN TNT). Pentolite has a compressive strength of 2000—2200psi at 1.68g/cc (Ref 12)... 

Explosive D is approx 80% as brisant as TNT, as indicated by sand tests, but fragmentation tests in shell have shown it to be about 95% as brisant. Both expls have about the same rate of detonation at a d of 1.56g/cc hence, approx equality of brisance would be expected. The rate of detonation of Explosive D has been found to be somewhat affected, particularly at lower loading densities, by the granulation of the material, but this effect is not pronounced. Its expl strength is 98% that of TNT, as evidenced by the ballistic pendulum test (see below)... 

Threshold shock pressures to initiate detonation in several SP are shown in Table 55. In general, unless the SP contains solid HE ingredients such as HMX or RDX, the threshold pressures are considerably greater than for solid HE at a comparable degree of compaction. Even so, the pseudo-composites of AP/wax must be considered to be rather shock-sensitive provided their degree of compaction does not exceed about 90% of their theoretical max density (TMD), Figure 21 shows that up to about 90% TMD the shock sensitivity of an 80/20 AP/wax composite is very similar to that of TNT... 

Tables 2.1 and 2.2 show that theory enables detonation velocities to be calculated in close agreement with those observed experimentally. This, unfortunately, is not a critical test of the theory as velocities when calculated are rather insensitive to the nature of the equation of state used. A better test would be to calculate the peak pressures, densities and temperatures encountered in detonation, and compare these with experimental results. The major difficulties here are experimental. Attempts to measure temperatures in the detonation zone have not been very successful, but better results have been obtained in the measurement of densities and pressures. Schall introduced density measurement by very short X-ray flash radiography and showed that TNT at an initial density of 1 -50 increased 22% in density in the detonation wave. More recently detonation pressures have been measured by Duff and Houston using a method (introduced by Goranson) in which the pressure is deduced from the velocity imparted to a metal plate placed at the end of the column of explosive. Using this method, for example, Deal obtains the detonation pressures for some military explosives recorded in Table 2.3. More...

Dense slurries which are not aerated and therefore have a density of about 1-4. The required sensitivity is achieved by the addition of substances such as TNT. 

Other factors that determine the catastrophic effects of an explosion are the initial density of the explosive (which is more than three orders of magnitude higher for TNT than for hydrogen-air mixture) and detonation velocity (which is three to five times higher in TNT). Therefore, the resulting pressure wave from a hydrogen explosion is considerably flatter (longer duration and lower maximum overpressure) than TNT, and destruction effects are mainly caused by impulse rather than overpressure. 

TLC is also one of the analytical techniques that is commonly used to support evidence in courts of law. The chemistry concept for visualization is not unique since this reaction scheme, converting explosive to pink dyes, is decades old. TLC provide rapid screening capability for the presence of a broad range of explosive residues. TLC also provides a means for obtaining specificity, i.e., identifying numerous types of explosives, their concentrations, and also provides the capability to ratio the amounts of the explosives present. For example, Comp B has a mixture of RDX and TNT in its formulation, and if present in the sample the ratio would be 60 40, respectively. This ratio becomes visually apparent by the density of the spots with TLC technology (See Figure 2). 

Mixtures of TNT, RDX, and/or AN are used as TNT-based explosives. Various additives such as aluminum powder, barium nitrate, and/or some other small amounts of materials are used. Densities are in the range 1450-1810 kg m"l Aluminum powder is added to obtain bubble energy when used in underwater conditions. 

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