The performance of explosives is intricately linked to environmental conditions, with temperature and moisture playing critical roles in their stability, sensitivity, and overall effectiveness [1]. These factors can significantly alter the chemical and physical properties of explosive materials, leading to variations in detonation velocity, brisance, and storage life.
Temperature effects: a double-edged sword
Temperature fluctuations, both high and low, can have profound effects on the performance of explosives.
High temperatures
At elevated temperatures, the chemical stability of many explosive compounds begins to degrade. The molecules within the explosive gain kinetic energy, increasing the likelihood of spontaneous decomposition. This can lead to a number of undesirable outcomes:
- Increased sensitivity: explosives can become more sensitive to initiation by shock, friction, or impact, increasing the risk of accidental detonation.
- Reduced performance: the decomposition of the primary explosive material can result in a decrease in the overall energy output and detonation velocity.
- Pressure buildup: in confined munitions, the evolution of gases from decomposition can lead to a dangerous buildup of pressure.
- Autoignition: in extreme cases, the temperature may reach the autoignition point of the explosive, causing it to detonate without any external stimulus.
For example, the widely used explosive Composition B, a mixture of RDX and TNT, exhibits changes in its detonation properties at elevated temperatures as the TNT matrix begins to melt. This can affect the distribution of RDX crystals and influence the propagation of the detonation wave.
Low temperatures
Conversely, low temperatures can also negatively impact explosive performance. As the temperature drops, the explosive material can become more brittle and less sensitive to initiation. This can result in:
- Decreased sensitivity: the energy required to initiate a detonation may increase, potentially leading to a failure to detonate under normal conditions.
- Incomplete detonation: the detonation wave may not propagate uniformly throughout the explosive charge, resulting in a partial or low-order detonation with significantly reduced effectiveness.
- Changes in detonation velocity: while the relationship can be complex and vary between different explosives, some, like XTX-8004, have shown a decrease in detonation velocity at lower temperatures.
Moisture: a detrimental influence
Moisture is generally considered detrimental to the performance and storage of most explosives. The absorption of water can lead to both physical and chemical degradation.
Effects of moisture absorption
- Reduced sensitivity and performance: water can act as a desensitizer, making the explosive more difficult to initiate. It can also absorb energy during the detonation process, leading to a lower detonation velocity and reduced brisance (the shattering effect of the explosive). For hygroscopic explosives like those based on ammonium nitrate, moisture absorption is a significant concern.
- Chemical decomposition: moisture can facilitate chemical reactions that degrade the explosive compounds. For instance, it can promote the hydrolysis of some explosives, breaking down the energetic molecules into less powerful or non-explosive substances.
- Physical changes: the absorption of water can cause swelling, caking, or dissolution of the explosive grains, altering the physical characteristics of the charge and negatively impacting its performance.
- Corrosion: in munitions, moisture can lead to the corrosion of metal casings and components, which can compromise the integrity and safety of the device.
For some specialized explosives, such as emulsion explosives, water is an integral part of the formulation [2]. However, the stability and performance of these explosives are still highly dependent on maintaining the correct water balance and preventing its separation from the oil phase.
To sum up, the optimal temperature and humidity conditions are required to ensure the safe storage and reliable working of explosives. Any alteration in these conditions can lead to a sequence of unwanted effects ranging from loss of efficacy to increased risk to safety.
Reference
[1] S. Wu, M. Fang, X. Wu, G. Guo, J. Wang, and S. Xu, “Effects of temperature, particle size, and air humidity on sensibility of typical high-energetic explosives,” Journal of Measurement Science and Instrumentation, vol. 15, no. 3, pp. 408–416, Sept. 2024, doi: 10.62756/jmsi.1674-8042.2024042.
[2] A. Maranda, D. Markowska, B. Kukfisz, and W. Jakubczak, “A Comprehensive Review of the Influence of Sensitizers on the Detonation Properties of Emulsion Explosives,” Applied Sciences, vol. 15, no. 5, p. 2417, Jan. 2025, doi: 10.3390/app15052417.
