Evan Rogers

Ammonium nitrate: thermal stability and explosivity modifiers

Abstract Two basic approaches to diminish the explosivity of AN have been suggested: dilution of ammonium nitrate (AN) with a chemically inert material or incorporation of small amounts of material which increases the chemical reaction zone [Method of Desensitizing AN and the Product Obtained, United States Patent Office, No. 3,366,468 (1968); Fertilizer additives: can AN be defanged? C&E News (1995) 6]. While small-scale tests of these “deterred” AN formulations appeared promising, larger amounts (30 pounds under confinement) were found to be detonable, though with reduced performance [Institute of Makers of Explosives Report, 1995]. In this study thermal analysis was used to screen a large number of AN formulations in search of possible deterrents. The sodium, potassium, ammonium and calcium salts of sulfate, phosphate, or carbonate as well as certain high-nitrogen organics (urea, oxalate, formate, guanidinum salts) were chosen because they should enhance AN thermal stability and because they could be used with agricultural products. This study considers whether laboratory tests can be used as benchmarks in evaluating explosivity.

Improvised Explosive Devices: Pipe Bombs

The fragments from 56 pipe bombs were collected (average recovery 87%), counted, weighed, sorted, and photographed. The matrix examined included eight energetic fillers, two initiation systems, three types of pipe, and several degrees of fill. The matrix and results are summarized in Table 1. For identical devices, the overall fragmentation pattern was surprisingly reproducible. The fragmentation patterns are presented in photos, but they are also reduced to numerical evaluators. A particularly useful evaluator is the fragment weight distribution map (FWDM) which describes explosive power with a single variable—the slope. This value is independent of device size and percent recovery. We believe this database of 56 pipe bombs is the largest controlled study of these devices. This study demonstrates the possibility that, even in circumstances where chemical residue cannot be found, sufficient evidence is present in the pipe fragments to identify the nature of the energetic filler.

NTO decomposition studies

To examine the thermal decomposition of 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO) in detail, isotopic labeling studies were undertaken. NTO samples labeled with {sup 15}N in three different locations [N(1) and N(2), N(4), and N(6)] were prepared. Upon thermolysis, the majority of the NTO condensed-phase product was a brown, insoluble residue, but small quantities of 2,4-dihydro-3H-1,2,4-triazol-3-one (TO) and triazole were detected. Gases comprised the remainder of the NTO decomposition products. The analysis of these gases is reported along with mechanistic implications of these observations.

Small-scale explosivity testing

Abstract In the area of energetic materials testing, correlation of small- and large-scale test results is a frequently sought and seldom achieved goal. We have experimented using the cartridge test to obtain a relative ranking of the explosivity of energetic materials. The cartridge test attempts to detonate a 2 gram sample of energetic material confined in a .303″ brass cartridge case with a number 8 blasting cap. Violence of an event was judged by the weight of the main body of the casing remaining attached to the base after detonation.

Synthesis and spectra of some 2H-, 13C-, and 15N-labeled isomers of 1,3,3-trinitroazetidine and 3,3-dinitroazetidinium nitrate

Abstract The title compounds were synthesized by utilizing appropriately labeled starting materials and reagents according to literature procedures.1,2 The products were characterized by NMR and mass spectral analysis. Unequivocal assignments of all NMR chemical shifts of the unlabeled title compounds and their intermediate precursors were facilitated by the NMR spectra of the labeled compounds along with carbon-hydrogen correlation experiments.

Mass Spectral Fragmentation Pathways in 1,3,3-Trinitroazetidine

The electron impact (EI) fragmentation pathways of 1,3,3-trinitroazetidine (TNAZ) along with some 15N and 2H analogs were studied. Collision-induced dissociation was also used to investigate important peaks in the EI spectra. Isotopically labeled compounds allowed the determination of most of the major fragmentation peaks. It was found that the major pathway involves the loss of NO2 or HNO2 from the dinitroalkyl group followed by a loss of NO2 or NO from the nitramine group. The peak at m/z 46, [NO2]+, the base peak, resulted primarily from N—N bond scission while the peak at m/z 30, [NO]+, was equally likely to come from any NO2 bond. The fragmentation pathway of TNAZ showed similarities with other nitramine and nitrocarbon explosives.

Gas production from thermal decomposition of explosives: Assessing the thermal stabilities of energetic materials from gas production data

Abstract The gas formation associated with the thermal decompositions of nineteen energetic materials was determined at three temperatures (120°C, 220°C and 320°C). Although there was considerable variability within classes, among the largest producers of gas were the nitrate esters. PETN (pentaerythritol nitrate) generated about 6.3mole gas per mole, while nitrocellulose, produced almost no gas. Second in gas production were the nitramines, followed by nitroarenes and lastly, energetic salts. NTO (5-nitro-2, 4-dihydro-3H-1, 2, 4-triazol-3-one), which does not fit into the four main classes of energetic materials, exhibited gas production (2.13 mole gas per mole NTO) comparable with some nitroarenes and the energetic salt, ammonium dinitramide (ADN). For selected compounds gas evolution data was used to construct first-order plots, from which Arrhenius parameters were determined and compared with previously reported values.