PETN Explosion Temperatures

Investigated explosives included 2,4,6-trinitrotoluene (TNT), 2,4,6,N-tetranitro-N-methylaniline (tetryl), l,3,5-trinitro-l,3,5-triazacyclohexane (RDX), 1,3,5,7-tetranitro-l,3,5,7-tetrazacyclooctane (HMX) and pentaerythritol tetranitrate (PETN). The temperature of the injector, cooled with liquid CO2, was —5°C for 0.3 min, programmed from —5 to 250° C, at a rate of 200°C/min, with a final hold time of 8.4 min. The column temperature was 80° C for 2 min, programmed to 250° C at 25°C/min, with a final hold of 2 min. Electron ionization (El) in the positive-ion mode was used. Figure 4 shows the mass chromatograms of a mixture of explosives (lOppb each), extracted from water by Hquid—liquid extraction and X 100 concentration. Identification was based on typical fragment ions for each one of the explosives. 

Pentaerythritol Tetranitrate, abbrd as PETN), C(CH2 0N02)4- Its prepn, props, uses and analysis are described by Belgrano (Ref 31, p 176—183) Its props given on p 181 of Ref 31 are as follows Density (max) 1.62, Explosion Temperature 195°, Flame Temperature on Explosion (Temperature Developed on Explosion)... 

Shoeiyaku. Pentaerythritol Tetranitrate (PETN), C(CH2ON02)4 mw 316.14, N 17.72% wh crysts, d 1.77, mp 141° Brisance by Plate Dent Test 129% TNT Explosion Temperature 225° (decomp in 5 secs) Impact Sensitivity BurMines-App, 2-kg Wt 17cm (vs 100+ for TNT) Power by Ballistic Mortar Test 145% TNT Rate of Detonation 8300m/sec (Ref 8, p 276). Pressed PETN was used in Army 7.7 12.7-mm Fuzeless Projectiles and 20-mm MG Projs. Also in Boosters. Its mixt with TNT is called Pentoriru (qv). PETN with 8.5% wax was used for loading 20-mm Shells. Its mixtures with RDX were used in 7.7 12.7-mm Projectiles. PETN was also used in Incendiary Mixtures (Ref 1, p 27 Ref 5, p 372)... 

Explosion Temperature. 133°(vs 225° for PETN) Heat Test at 75°. exploded in 30 minutes Impact Sensitivity. 2kg wt, PicArsnApp, 2 inches (PETN 6 inches)... 

Explosion Temperature, dec inr5 mins at 200° Friction Pendulum Test — snaps by steel shoe Heat Test at 100°, % Loss — 2.0 after 1st 48 hrs, 0.2 after 2nd 48 hrs and no expln in 100 hrs Heat Test at 120°— salmon pink after 150 mins, red fumes at 300+ and then explodes Hygroscopicity — 6.2% gain at 30°C and 90% RH Impact Sensitivity, BurMinesApparatus, 2kg wt 19cm (comparable to PETN)... 

Its expl and other props, given in R.efs 2,3,4 5), are as follows Ballistic Mortar Value (Power) 127%TNT Explosion Temperature ignites ca 340°, but does not expl even at 360° (same as for TNT) Friction Sensitivity- si less sensitive than RDX Heat of Combustion, Qc 769.8 kcal/mole Heat of Explosion, Qe 272.6 kcal/mole Heat of Formation, 27.8 kcal/mol Hygroscopicity- increase in wt at 100% RH 0.09% vs 0.03% for TNT not hygroscopic at 90% RH Impact Sensitivity, detd by BurMinesApp No 5- si less sensitive than PETN 75° International Heat Test loss of wt in 48 hrs 0.1% vs 0.2% for TNT Power- see Ballistic Mortar Value and Trauzl Value Stability. Thermal at 100°- no expln in 300+ mins(same as for TNT) Stability, Thermal at 2 35°- methyl violet turned salmon pink in 30 mins vs 300+ mins for TNT Temperature of Explosion 3885°K Trauzl Test Value 135% TNT ... 

Only relatively few compounds can act as primary explosives and still meet the restrictive military and industrial requirements for reflabiUty, ease of manufacture, low cost, compatibiUty, and long-term storage stabiUty under adverse environmental conditions. Most initiator explosives are dense, metaHoorganic compounds. In the United States, the most commonly used explosives for detonators include lead azide, PETN, and HMX. 2,4,6-Triamino-l,3,5-triuitrobenzene (TATB) is also used in electric detonators specially designed for use where stabiUty at elevated temperatures is essential. 

Pentaerythritol may be nitrated by a batch process at 15.25°C using concentrated nitric acid in a stainless steel vessel equipped with an agitator and cooling coils to keep the reaction temperature at 15—25°C. The PETN is precipitated in a jacketed diluter by adding sufficient water to the solution to reduce the acid concentration to about 30%. The crystals are vacuum filtered and washed with water followed by washes with water containing a small amount of sodium carbonate and then cold water. The water-wet PETN is dissolved in acetone containing a small amount of sodium carbonate at 50°C and reprecipitated with water the yield is about 95%. Impurities include pentaerythritol trinitrate, dipentaerythritol hexanitrate, and tripentaerythritol acetonitrate. Pentaerythritol tetranitrate is shipped wet in water—alcohol in packing similar to that used for primary explosives. 

Four nitrosamines, seven nitramines, three nitroesters and the explosives Semtex 10 and Composition B have been investigated by TGA. Linear dependence was confirmed between the position of the TGA onsets, as defined in the sense of Perkin-Elmer s TGA-7 standard program, and the samples weights. The slope of this dependence is closely related to the thermal reactivity and molecular structure. The intercept values of the dependence correlate with the autoignition temperatures and with the critical temperatures of the studied compounds, without any clear influence from molecular structure. Results show that Semtex 10 exhibits approximately the same thermostability as its active component pentaerythrityl tetranitrate (PETN, 274). Results also show that TGA data for Composition B do not correlate with analogous data for pure nitramines564. 

Of the explosives listed in Table 4, only those such as NG with vapour pressures greater than 10 Pa at 25°C are good candidates for the direct detection of vapour by current instrumental techniques. However, vapour pressure rises markedly with temperature. In addition, consideration of the thermal stability data in Table 4 offers the possibility of heating samples containing traces of involatile explosives such as RDX or PETN to increase their vapour pressure and render them detectable. This is the basis of the common technique of combining a heated inlet system with a vapour-type detector, for example, the method of desorption from a swab on a heated stage often used with IMS or TEA systems. This approach has greatly broadened the scope of what were previously viewed as vapour-type detectors and is now standard practice such instruments are now known as particle detectors. 

Another approach to a source of vapors to calibration of instruments, and similar to that described above, was that of Davies et al. [67] who used a computer-controlled pulsed vapor generator with TNT, RDX, and PETN. The explosive solid was coated on quartz beads, which were then packed into a stainless steel tube. The tube was coiled and placed into a temperature-controlled chamber. Ultrapure air was passed through the coil at temperature and vapors of explosives were vented from the coil at rates or concentrations governed by coil temperature, airflow rate, and pulse width. Calibrations could reach the picogram to nanogram range when an IMS analyzer was used as the calibrating instrument. 

The spectra in Figure 11.4 were recorded from headspace vapor either at room temperature (TNT, PETN) or elevated temperature (about 50°C for RDX). For TNT this corresponds to a saturated headspace vapor pressure of less than 10 ppb. At these levels strong signal is observed with relatively weak signal from room air. Explosives compounds that have been detected by the MS detector with high sensitivity include TNT, ADNT, DNT, NT, TNB, DNB, DMNB, RDX, HMX, EGDN, NG, PETN, and TATP. (see Explosive Definitions, page 329). 

Measurements. Combustion temperatures of PETN, RDX Tetryl were measured at 20-100 atm in a constant-pressure bomb under a N2 atmosphere (Refs 2 3). The absorptivities of the PETN and Hexogen flames were 0.1-0.3 and that of the Tetryl flame 0.8-0.9. In all cases the flame absorptivity increased toward the surface of the charge. If secondary explosives are volatile, as noted by Belyaev... 

The isothermal method for such expls as PETN, RDX, NG and Tetryl is complicated by autocatalysis to such an extent that one cannot determine the intrinsic (pure explosive) decompn rate from the logw vs t curves and their change with temperature. Hence, the results obtd by the adiabatic(sensitivity) methods may be more reliable from this viewpoint (Ref 8, p 177)... 

This distinction is more in kind than in degree. Small quantities of primary or initiating explosives usually detonate when exposed to flames or high temperatures whiie secondary explosives usually burn or deflagrate under these conditions. However under slightly altered conditions primary explosives can be made to deflagrate and secondary explosives can be made to detonate. Examples of primary explosives are Lead Azide, Mercury Fulminate, DDNP, etc Examples of secondary explosives are PETN, RDX, HMX, Tetryl, TNT, as single HE compns and Comp B, Comp C, PBX 9404, Dynamite ANFO (Ammonium Nitrate/Fuel Oil) as HE mixtures... 

The vacuum stability test (VST) is considered the most acceptable test for measuring stability and compatibility of explosives, worldwide. This is an empirical test in which rate of gas evolution is measured under isothermal conditions and a limit of 01 cm3 of gas per gram of an explosive is set for explosives heated at 120°C (150°C for RDX) for 40h (25h for PETN). A similar test but at somewhat lower temperatures, is used to assess compatibility of an explosive with other explosives or with non-explosive materials such as binders (polymers), plasticizers etc. 

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