The kinetic behaviour and thermal stability of commercially available explosives

Manufactures of commercially available explosives guarantee a certain lifetime of their products. In the commercial field this lifetime is usually large enough. The explosive is normally used long before the end of its lifetime. It may happen that these explosives are stored for a long time in a bunker where they sometimes exceed their lifetime. A large set of commercial explosives is characterized with a TG by heating small samples in aluminium sample cups from room temperature to 550°C, under a nitrogen atmosphere, with three different heating rates (2, 5 and 10 K min-1). The activation energy of the decomposition step is determined in several different ways. After this characterization, a selection of the samples (based on economical value) is artificially aged for periods of 2, 4 and 6 weeks. After these ageing profiles the samples are re-investigated with the TG under the same conditions (heating rates and atmosphere) followed by the calculation of the kinetic parameters of the artificially aged materials. According to the TG measurements almost all tested explosives appear to have a much longer lifetime than the values given by the manufacturer. From kinetic point of view, the different methods for calculating the activation energy result in approximately the same parameters. It may conclude that TG seems to be a reliable and quick method for the determination of the lifetime of commercial explosives.