Showing papers in "Journal of Energetic Materials in 1987"
TL;DR: A less sensitive explosive, 3-nitro-1,2,4-triazol-5-one (NTO) has a crystal density of 1.93 g/cm 3 and calculated detonation velocity and pressure equivalent to those of RDX as discussed by the authors.
Abstract: A less sensitive explosive, 3-nitro-1,2,4-triazol-5-one. The compound 3-nitro-1,2,4-triazol-5-one (NTO) has a crystal density of 1.93 g/cm 3 and calculated detonation velocity and pressure equivalent to those of RDX. It can be prepared in high yield from inexpensive starting materials in a safe synthesis. Results from initial small-scale sensitivity tests indicate that NTO is less sensitive than RDX and HMX in all respects. A 4.13 cm diameter, unconfined plate-dent test at 92% of crystal density gave the detonation pressure predicted for NTO by the BKW calculation.
226 citations
TL;DR: In this paper, the authors compared MINDO/3, MNDO and AM1 calculations to each other and to available experimental data for 105 nitro-compounds, both aliphatic and aromatic.
Abstract: Although the MINDO/3, MNDO and AM1 molecular orbital programs accurately predict physical properties for a wide variety of classes of chemical compounds, their ability to estimate the physcial properties of nitro-compounds has not been rigorously tested. This paper compares MINDO/3, MNDO and AM1 calculations to each other and to available experimental data for 105 nitro-compounds – both aliphatic and aromatic. Properties evaluated include heats of formation, dipole moments, ionization potentials and molecular geometries. In general MINDO/3 predicts heats of formation, dipole moments and ionization potentials more accurately than MNDO and AM1. All three semi-empirical methods accurately predict molecular geometries.
17 citations
TL;DR: In this paper, a critical assessment of the likely modes of thermal decomposition of RDX is given, and it is suggested that these radicals are not primary decomposition products, but are formed by the reaction of the radical products of thermal decompposition with molecular oxygen.
Abstract: A critical assessment is given of the likely modes of thermal decomposition of RDX. Previous publications by other authors report that thermally decomposed RDX produces nitroxide and nitronylnitroxide radicals as intermediates. These results are discussed, and it is suggested that these radicals are not primary decomposition products, but are formed by the reaction of the radical products of thermal decomposition with molecular oxygen.
16 citations
TL;DR: In this article, the experimental detonation pressure of explosives has been found to correlate reasonably well with the theoretical specific impulse and density of these compositions; however, the equation containing Isp × Density2, a Kamlet-Jacobs like term, was found to show the best relationship for predicting, today's plastic bonded explosives.
Abstract: The experimental detonation pressure of explosives has been found to correlate reasonably well with the theoretical specific impulse and density of these compositions. Two data sets were subjected to linear regression analysis, giving a number of possible correlations; however, the equation containing Isp × Density2, a Kamlet-Jacobs like term, was found to show the best relationship for predicting, today's plastic bonded explosives. The complete equation is:
13 citations
TL;DR: In this article, a 40-MeV electron beam has been used to uniformly heat confined samples of high explosives until explosion, and values were obtained for the thermal initiation thresholds (deposited energy per gram until explosion) and explosion temperatures.
Abstract: A 40-MeV electron beam has been used to uniformly heat confined samples of high explosives until explosion occurs. From observations of temperature vs time, values were obtained for the thermal initiation thresholds (deposited energy per gram until explosion) and explosion temperatures. These are good indicators of thermal explosion sensitivity. In many cases, the specific heat or the latent heat of fusion were obtained. Data were obtained on the following materials: HMX, PBX-9404, RDX, HBX-1, Comp. A-3, PBXW-109, TATB, TNT, ONP, DIPAM, NDAC, TNB and TNBA. Thermal threshold values vary from 57 cal/gm to 168 cal/gm for these materials. There is some indication that these results are correlated with data from impact sensitivity tests. Radiationinduced decmposition is shown to be very small.
7 citations
TL;DR: In this paper, the authors synthesize and characterize selected organodi-and polyammonium nitrate salts for use in a qualitative study of thermal and impact stability characteristics, including densities (calculated and measured), heats of fusion, melting points, the temperature of the major peak associated with expthermic decomposition as measured by a differential scanning calorimeter and Fourier transform infrared spectra.
Abstract: The objective of this investigation was to synthesize and characterize selected organodi- and polyammonium nitrate salts for use in a qualitative study of thermal and impact stability characteristics. A total of twenty-two salts were prepared and characterized. A literature search confirmed that fifteen of these materials had never been reported and, therefore, were assumed to be original. The general synthesis process is described with specific details for each compound included. Elemental analyses are provided for the new compounds as well as their nuclear magnetic resonance spectra. Other data included are densities (calculated and measured), heats of fusion, melting points, the temperature of the major peak associated with expthermic decomposition as measured by a differential scanning calorimeter and Fourier transform infrared spectra.
7 citations
TL;DR: In this article, short-pulse initiation experiments were conducted on PBX 9502 using explosively driven magnesium flyer plates of thicknesses from 0.5 to 2.0 mm.
Abstract: Short-pulse initiation experiments were done on PBX 9502 using explosively driven magnesium flyer plates of thicknesses from 0.5 to 2.0 mm. Input pressure was 13.1 GPa. Magnesium is a good impedance match to PBX 9502 so the input pulses were clean and sharp. In-material particle velocity histories were obtained using the axisymmetric magnetic probe, and shock trajectories were measured using the wedge technique. For 0.5 and 1.0-mm-thick flyers no initiation of detonation was observed. For 2-mm-thick flyers giving a pulse duration of about twice the steady reaction zone time a run to detonation of 11.8 ± 1.1 mm was measured; this is 50% longer than the run for a sustained shock for the same input pressure.
6 citations
TL;DR: The subject compound (I) containing eight geminal azide groups was prepared and briefly evaluated as discussed by the authors, and the subject compound was used for the first time in the application of the test set.
Abstract: The subject compound (I), containing eight geminal azide groups, was prepared and briefly evaluated.
5 citations
TL;DR: In this paper, the authors measured the velocities of the particles of a jet after breakup and found that the distribution contained an approximately constant velocity section of several particles immediately behind the tip.
Abstract: We have measured the velocities of the particles of a jet after breakup and found that the distribution contained an approximately constant velocity section of several particles immediately behind the tip. The jet was produced from a centrally initiated, 38 mm diameter conical shaped charge. Since the measurements were carried out after jet formation, the observation is not considered to be directly related to the inverse-velocity gradient effect that produces the tip particle. Comparison between calculated and measured jet penetration velocities show that the calculations assuming a uniformly stretching jet require modification to take account of the observation. A possible explanation for the origin of the non-ideal behaviour is that the short height of explosive between the detonator and liner (the explosive head height) produces a building detonation which strikes the liner with a varying impulse and curvature. Some support for the observation is found in earlier experimental work by DiPersio...
3 citations
TL;DR: In this paper, the mass spectrum and the time evolution of the freely expanding products of HNS detonation were determined and compared with those obtained under conditions closer to equilibrium and to earlier measurements of the same kind with PETN.
Abstract: We have determined the mass spectrum and the time evolution of the freely expanding products of HNS detonation. The products arriving at the detector earliest have velocities of 8 km s−1; except for hydrogen, this is characteristic of all of the products irrespective of mass. The spectrum is dominated in intensity by products at mass 28, which we ascribe as composed of 80% CO and 20% N2. These account for nearly half the total products. The remaining products are spread over many mass peaks from mass 12 to mass 60, the most important being H2, N2O, CO2 and carbon clusters. We observe carbon in clusters, Cn, with 1 ≤ n ≤ 5 in a distribution that decreases monotonically with n. Carbon cluster distributions are also obtained under conditions of partial confinement by solid Xe at 30 K and the distributions are found to be relatively unchanged. We compare our mass spectrum with those obtained under conditions closer to equilibrium and to earlier measurements of the same kind with PETN.
3 citations
TL;DR: In this article, needle-like crystalline PETN explosive powders to make them pourable were introduced by the application of about 80 A thick polymeric coatings to the individual crystals, followed by a controlled agglomeration into a spherical prill.
Abstract: Manufacture of precision detonators requires the pelletizing of very fine, organic, crystalline explosive powders. Production of pellets in automatic machines within critical dimensional and weight tolerances requires that the powders pour uniformly into die cavities. The pellets must be able to be initiated with low energy and have a predictable energy output. Modifications to needle-like crystalline PETN explosive powders to make them pourable were introduced by the application of about 80 A thick polymeric coatings to the individual crystals, followed by a controlled agglomeration into a spherical prill. Microencapsulation techniques provided the key to achieving the result using less than 0.5 wt. % coating (an order of magnitude less coating than in usual PBX systems). These coatings did not appreciably alter the energy required to initiate and significantly increased the strength of the pellets. A key point demonstrated, which may be translated to other applications, was that powders that exhibit performance based on physical characteristics could have their handling and strength properties tailored with little change in their primary function.
TL;DR: In this paper, the axisymmetric steady mach stem formation and structure in high-explosive detonation mach stems is studied. But the results are presented, along with experimental evidence that confirms the validity of the calculations.
Abstract: High explosive detonation mach stem phenomena is a relatively new research area which has been studied only since the early 1960's. Although non-steady mach stems in gases have been studied extensively, steady state mach stems have been largely ignored, particularly in high explosives. None the less, steady state detonation mach stems are of great interest due to the observability of continuous highly overdriven detonations. In order to gain a better understanding of axisymmetric steady mach stem formation and structure in high explosives, two dimensional dynamic Lagrangian numerical simulation was done. The results are presented, along with experimental evidence that confirms the validity of the calculations.
TL;DR: In this article, the effect of two volume percent air holes on the reaction zone was modeled using the three-dimensional Eulerian reactive hydrodynamic code, 3DE, for PBX-9404.
Abstract: The calculated reaction zone of PBX-9404 using solid HMX Arrhenius kinetics is stable to perturbations. The calculated reaction zone Von Neumann spike pressure agrees with the experimental observations within experimental uncertainty associated with different experimental techniques. The calculated homogeneous explosive reaction zone thickness is larger than observed for the heterogeneous explosive. The effect of two volume percent air holes on the reaction zone was modeled using the three-dimensional Eulerian reactive hydrodynamic code, 3DE. The air holes perturb the reaction zone. A complicated, time-dependent, multi-dimensional reaction region proceeds through the heterogeneous explosive. The experimentally observed reaction zone characteristic of heterogeneous explosives are mean values of an irregular, three-dimensional reaction region.
TL;DR: The previously reported compound N-nitro-N'-(2, 2,2,2-trinitroethyl) guanidine (3) is shown by 1H NMR spectroscopy to be actually the corresponding nitrimine tautomer N''-nitron-N-(2, two, 2-trinitriethyl) as discussed by the authors.
Abstract: The previously reported compound N-nitro-N'-(2,2,2-trinitroethyl) guanidine (3) is shown by 1H NMR spectroscopy to be actually the corresponding nitrimine tautomer N''-nitro-N-(2,2,2-trinitroethyl)...
TL;DR: In this article, a cell for high pressure sound velocity measurements of liquids was designed and used in a Birch-Bridgman high pressure system with a liquid propellant specimen, and the dependence of the sound velocity on pressure to 4.2 kbar (4200 atmospheres) was measured at room temperature and on temperature between 220 and 293 K at room pressure.
Abstract: A cell for high pressure sound velocity measurements of liquids was designed and used in a Birch-Bridgman high pressure system with a liquid propellant specimen. The dependence of the sound velocity on pressure to 4.2 kbar (4200 atmospheres) was measured at room temperature and on temperature between 220 and 293 K at room pressure. These data, together with the temperature dependence of the specific heat which was also measured, and some thermodynamic arguments were used to obtain the full equation of state with temperature and the pressure dependence of the specific heat and of the volume expansivity at room temperature. We compare our results with data obtained by volumetric and other ultrasonic measurements.
TL;DR: In this paper, the AM1 and MNDO methods were used to calculate the geometries and bond strengths of a number of nitro-aromatic compounds, and they gave an absolute error of about 35 kcal/mole in bond strengths relative effects within the group of compounds are predicted somewhat better.
Abstract: The size of most actual energetic materials will limit calculation of their properties to the semi-empirical methods To calibrate the abilities of the semi-empirical methods, the geometries and bond strengths of a number of nitroaromatic compounds have been calculated by the AM1 and MNDO methods The AM1 method does well in predicting geometries, predicting a planar NO2 group in most cases Both methods give an absolute error of about 35 kcal/mole in bond strengths Relative effects within the group of compounds are predicted somewhat better