RESUMO
The use of increasingly advanced energetic materials (EMs) in various branches of industry and military sectors increases the appropriate requirements for EMs, including: their durability, safety of use, chemical and high-energetic properties. Additionally, the impact of the products of the explosion of EMs on the natural environment is also crucial. Therefore, on-site mixture (OSM) energetic materials containing concentrated hydrogen peroxide (OSM-type energetic materials) are becoming increasingly popular. This is an extremely interesting group of materials that contains in excess of 50 wt.% hydrogen peroxide (HP) and not containing toxic compounds, and therefore is environmentally friendly. The main objective of the study was to investigate the various compositions of OSM-type energetic materials in terms of the evolution over time of their energetic properties (including the "raw" energetic material strength and the ability to sustain the propagation of a detonation wave) and the volume of the post-detonation gases. The obtained results show that the decomposition of hydrogen peroxide strongly affects the detonation parameters of OSM-type energetic material and the decomposition time of HP. In addition, it has been proven that rate of decomposition of HP significantly affects the detonation parameters of OSM-type energetic materials. It was also found that the concentration of NO x is low and decreases dramatically with the decomposition of hydrogen peroxide, but at the same time the concentration of carbon oxides increases.
RESUMO
The aims of this study were to investigate the potential of utilising molecularly imprinted polycarbazole layers to detect highly toxic picric acid (PA) and to provide information about their performance. Quantum chemical calculations showed that strong interactions occur between PA and carbazole (bond energy of approximately 31 kJ/mol), consistent with the theoretical requirements for effective molecular imprinting. The performance of the sensors, however, was found to be highly limited, with the observed imprinting factor values for polycarbazole (PCz) layers being 1.77 and 0.95 for layers deposited on Pt and glassy carbon (GC) electrodes, respectively. Moreover, the molecularly imprinted polymer (MIP) layers showed worse performance than unmodified Pt or GC electrodes, for which the lowest limit of detection (LOD) values were determined (LOD values of 0.09 mM and 0.26 mM, respectively, for bare Pt and MIP PCz/Pt, as well as values of 0.11 mM and 0.57 mM for bare GC and MIP PCz/GC). The MIP layers also showed limited selectivity and susceptibility to interfering agents. An initial hypothesis on the reasons for such performance was postulated based on the common properties of conjugated polymers.
RESUMO
Ammonium nitrate-fuel oil (ANFO) explosives are inexpensive and readily produced, but are highly prone to misfires, with the remaining explosive being a significant risk and environmental contaminant. In this work, studies on various additives, such as selected perchlorates and inorganic peroxides, which are intended to lower the susceptibility of ANFO to misfires by increasing its sensitivity to shock, have been conducted. These studies showed the viability of using these additives in ANFO, allowing for conducting shock wave sensitivity tests for bulk charges in the future. We investigated the effects of introducing these additives into ANFO (on its sensitivity), as well as thermal and energetic properties. We observed minor increases in friction and impact sensitivity, as well as a moderate reduction in the decomposition temperature of the additive-supplemented ANFO in comparison to unmodified ANFO.
RESUMO
The issues of safety and its impact on both human health and the environment are on-going challenges in the field of explosives (EXs). Consequently, environmentally-friendly EXs have attracted significant interest. Our previous work, dedicated to on-site mixed (OSM) EXs utilising concentrated hydrogen peroxide (HTP) as an oxidising agent, revealed that the gradual decomposition of HTP may be harnessed as an additional safety measure, e.g., protection from theft. The rate of HTP decomposition is dependent on the OSM components, but this dependence is not straightforward. Relevant information about the decomposition of HTP in such complex mixtures is unavailable in literature. Consequently, in this work, we present a more detailed picture of the factors influencing the dynamics of HTP decomposition in EXformulations. The relevant measurement and validation methodology is laid out and the most relevant factors for determining the rate of HTP decomposition are highlighted. Among these, the choice of auxiliary oxidising agent is of particular relevance and it can be seen that the choice to use ammonium nitrate (AN), made in previous works dealing with HTP-based EXs, is sub-optimal in terms of maintaining the stability of HTP. Another important finding is that glass microspheres are not as inert to HTP as would be expected, as replacing them with polymer microspheres significantly slowed the decomposition of HTP in the investigated OSM samples.
RESUMO
Ammonium nitrate-fuel oil (ANFO) is one of the most widely used explosives for civilian purposes. Its main advantages are its low price and simple method of production. The main disadvantages of this material are low water resistance and problems related to non-ideal detonation, which can be a potential hazard when using ANFO. Due to this, research has been conducted for many years to find suitable additives for ANFO that would have the effect of offsetting its drawbacks. The aim of this review was to describe factors affecting the energetic properties of ANFO, including the highlighting of substances that could potentially be additives to ANFO formulations that would reduce the negative effects of non-ideal detonation, while avoiding adversely impacting the effectiveness of the explosive in blasting operations, as well as its sensitivity parameters.