Nitroglycerin (NG) is a high explosive that is difficult to handle in its liquid form, where the entrapment of gaseous NG bubbles results in its high sensitivity to impact (<0.25 J). NG-based materials are traditionally prepared by complex mixing processes where desensitisation is of major concern. Instead of using a mixing procedure here we demonstrate the successful synthesis of dynamite-like materials by using a single step bottom-up approach to form a polymeric host matrix (PM) for NG from a solution which contains the explosive and the matrix precursors. For this purpose, an epoxidized vegetable oil mixed with nitroglycerin (oil to NG mass ratio of 60/40) is polymerized at 100 & DEG;C for 30 h by using glutaric acid as crosslinking agent. No degradation of NG under these conditions is observed. The activation energy of NG desorption from the PM (51.9 kJ/mol) is of the same order of magnitude as the one reported in literature for a double-base powder (81.9 kJ/mol). An accelerated NG desorption is observed as temperature increases. This can be attributed to a slow diffusion mechanism of the explosive from the volume to the surface of the material, where it evaporates. The ignition of NG/PM in air by an open flame leads to a self-sustained combustion, in which a part of nitroglycerin decomposes in the polymer matrix. Conversely, NG/PM monolithic and granular loads are not ignited by the explosion of the primer in a 9 mm calibre casing. The shockwave released by a detonator on a small NG/PM cylindrical charge (& AP;1.5 g) does not detonate it, but only makes it deflagrate. Our results show that this novel single-step synthesis of NG trapped in a polymeric matrix is a very effective approach for desensitizing it to any form of stress.

Melamine (Mel) was used as host matrix for liquid nitroglycerin (NG), to prepare Mel/NG solid powdered compounds containing up to 45 wt% of this explosive. The two preparation processes used for this purpose consisted in evaporating a solution of both components, either in ambient conditions or under reduced pressure by the Spray Flash-Evaporation (SFE) process. In Mel/NG materials, amorphous nitroglycerin is distributed in the crystallized melamine matrix as inclusions, which were found to be smaller in size in the material prepared by the SFE process. Mel/NG materials are not stable over time: they gradually lose the nitroglycerin they contain by evaporation.

A new kind of THKP was prepared by combining submicron potassium perchlorate made by the Spray Flash Evaporation (SFE) process with titanium hydride. Spray Flash Evaporation is based on flash evaporation to manufacture nanoparticles. The solvated product is nebulized in a chamber, which is maintained under vacuum, thanks to an atomization nozzle. The sudden fall of pressure induces a flash evaporation of the solvent and then crystallization of the product in the form of nanosized particles. This process was used on potassium perchlorate in order to produce nanosized particles of this product. This new type of potassium perchlorate prepared by SFE shows a particle size ranging from 50 to 400 nm. With this submicron sized potassium perchlorate, a better oxidation of titanium hydride was observed and also a transition to detonation in the THKP. This detonation transition was noted when the THKP is placed in a small diameter tube (3 mm) in loose powder. In the same time, the detonation velocity of this type of THKP increased to a value of approximatively 1250 m/s with a porosity of 86%. In comparison, micron sized potassium perchlorate in THKP tested in the same condition, no transition to detonation was observed and sometimes combustion stops. The sensitivities of THKP prepared with submicron sized potassium perchlorate are relatively high with an impact sensitivity of 44.7 J, a friction sensitivity of 192 N and an electrostatic discharge sensitivity of 34.7 mJ. THKP mixtures prepared from submicron potassium perchlorate can be classified as low-sensitivity primary explosives.

The pyrotechnic compositions made up of potassium perchlorate (KClO4) and titanium hydride (TiH2), known as THKP, have a fast deflagration velocity (similar to 500 m/s), along with low sensitivity and high stability. In this research, a new kind of THKP was formulated from a submicron powder of KClO4 (50-400 nm) prepared by the Spray Flash-Evaporation (SFE) process. The use of fine KClO4 not only ensures better oxidation of TiH2, but also leads to a transition to detonation in the THKP. This transition is observed in loose powders placed in small diameter tubes (3 mm). The distance of transition is relatively short (17-22 mm) and increases with the KClO4 content of the THKP mixture. The detonation front propagates steadily, at a velocity of similar to 1250 m/s in THKP powders with 86 % of porosity. The shockwave velocity varies little with the perchlorate content in the domain of composition studied (55-74 wt.% of KClO4). Conversely, in the classical THKP mixtures prepared from micron-sized KClO4 and tested in the same conditions, no transition to detonation is observed; the combustion slows down and eventually stops. Finally, owing to their high sensitivity thresholds to impact (S-Imp.>= 44.7 J), friction (S-Fr.>= 192 N), and electrostatic discharge (S-ESD >= 34.7 mJ), THKP mixtures prepared from submicron KClO4 can be classified as low-sensitivity primary explosives.

This article reports on a new family of detonating compositions in which ammonium dinitramide (ADN) is used as an explosive oxidizer, and red phosphorus (P-r) or titanium hydride (TiH2) as fuels. At optimized ADN/fuel ratios, these compositions have typical explosion heats higher than 7 kJ/g, detonation velocities in 3 mm diameter tubes ranging from 1.2 to 2.0 km/s at similar to 40 % of their theoretical maximum density, with a run to detonation distance between 20 and 40 mm. Both compositions are insensitive to electrostatic discharge, but are very sensitive to impact and friction, ADN/P-r mixtures being the most sensitive to these stress. The shockwave released by the reaction of these materials, efficiently initiates the detonation of high explosives such as pentaerythritol tetranitrate (PETN) or hexogen (RDX). In view of these characteristics, ADN-based detonating compositions must be considered as "green" substitutes for primary explosives containing heavy metals.

The purpose of this article is to alert our peers on the danger faced by those who carry out experiments involving molten ammonium dinitramide (ADN). In recent experiments aiming at preparing submicron particles of this compound, a preliminary study of the sensitivity to impact of molten ADN was performed. These first tests have shown that the sensitivity threshold of molten ADN to impact is more than one order of magnitude lower that the one on solid ADN (<0.25 J vs. 4 J) and similar to the one of nitroglycerin (<0.25 J), making liquid ADN extremely hazardous to handle. Detonation tests, which were performed in strong steel sheaths open to one end, have shown that the initiation of the detonation and its subsequent propagation occur both in solid and liquid ADN charges, having a diameter of only 4 mm. The critical diameter of solid ADN which is between 25 and 40 mm according to literature, is therefore decreased by at least an order of magnitude when ADN is placed in strong metallic confinement. On the other hand, the detonation of liquid ADN produces stronger destructive effects than the detonation of solid ADN, meaning that the detonation mechanisms of this explosive are different in its two physical states. In conclusion, liquid ADN must be considered in practice as a more hazardous and powerful explosive than solid ADN. This raises the issue of all experiments in which ADN is likely to be formed in molten state.