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Ammonium nitrate (AN) is a strong oxidizer that undergoes phase transitions and thermal decomposition at relatively low temperatures. This—as verified by historical facts—constitutes a challenge for the fire department during rescue operations. AN is also a highly reactive material widely used for the production of, i.a., fertilizers and explosives. The latter are popular not only in military applications but also in industrial ones, such as mining. They include ammonites and amatols utilized in coal mining, as well as Ammonium Nitrate Fuel Oil (ANFO) utilized in, i.a., rock mining. As a simple and cheap material, ANFO also tends to be used by terrorists. The spontaneous formation of an AN and polymers mixture—similar to ANFO in terms of composition and explosion force—was observed in fire conditions during previous research. At individual stages (from creation to exploitation), AN often comes into direct contact with various polymers. Polyolefins, in particular polyethylene (PE) and polypropylene (PP), are among the most popular groups of such materials. They are used for the production of, i.a., foil packaging and flexible intermediate bulk containers for the storage and transport of fertilizers. Despite the frequent mutual contact of these materials, there is little information in the literature on the interaction of AN and its polymer-made packaging in fire conditions. For this reason, it was decided to conduct a series of thermal analyses using Differential Scanning Calorimetry (DSC) to study the material behavior under the influence of high temperature. As it turns out in practice, the spontaneous formation of a mixture similar to ANFO—in terms of composition and explosion force—can be observed in fire conditions. Due to the results indicating a potentially explosive course of the reaction, laboratory tests on the macro scale were also carried out. The performed observations show that it may be necessary to create a procedure containing several different test methods in order to predict a mixture's behavior during a fire and to define the appropriate guidelines for firefighting teams. Such guidelines would enable firefighters to prepare the right equipment during a firefighting operation and to develop a strategy based on the observed course of events. [ABSTRACT FROM AUTHOR]

Polyurethanes (PURs) are a group of polymers with the most versatile properties and the broadest spectrum of application. Their name comes from the urethane group. PURs were introduced to the market on a large-scale basis by Bayer in 1942, in the form of Perlon U and Igamid U fibers produced by gradual polyaddition of diisocyanates and polyols. The development of PURs-production technology and the multitude of applications resulted in their widespread use. This group is so extensive that polyurethanes alone accounted for about 6% of the global production of polymers (2019)—most of them in the form of foam. Therefore, polyurethane can be found in a huge number of products—some of them stored in the vicinity of ammonium nitrate (AN). In the previous two articles, we showed that polymers and AN—stored within the same building—in fire conditions may, under certain circumstances, spontaneously transform into a material of explosive properties. The aim of this article is to check whether PUR, when in contact with AN, creates additional hazards, similarly to the previously tested polymers. [ABSTRACT FROM AUTHOR]

This article is a continuation of a case study in which we presented the results of research on processes generated under fire conditions by mixing molten ammonium nitrate (AN) with selected polymers. Here, we present an analysis of how certain materials, which may frequently appear in farm buildings and are commonly used in the immediate vicinity of humans, can potentially form explosives. The chosen materials include polyamides (PA) from which the wear-resistant machine elements are made (e.g., high-performance gears, wheels of transport trolleys); polyvinyl chloride (PVC) used, i.e., in construction carpentry, electrical insulation, and hydraulic pipes; polystyrene (PS) used, i.e., in insulation and containers; and poly(methyl methacrylate) (PMMA), i.e., so-called organic glass and plexiglass. The research results showed that these seemingly harmless and safe materials, mixed with AN and heated under fire conditions, may turn into explosives and stimulate stored AN. This creates significant risks of an uncontrolled fire progress. [ABSTRACT FROM AUTHOR]

On 2 October 2003 in Saint-Romain-en-Jarez (France) a fire in a farm building triggered an explosion in which 26 people were injured. Police investigation, based solely on an analysis of the effects and on general engineering knowledge, showed that the explosion was caused by an uncontrollably generated mixture of ammonium nitrate (AN) and molten plastic crates which formed an explosive mixture similar to ammonium nitrate fuel oil (ANFO). This is the only commonly known example of an ammonium nitrate blast taking place at its end user destination. Is such an explanation of the incident plausible and could a similar blast possibly happen anywhere else? The experimental results support this thesis of French investigators but raise further doubts. Laboratory reconstruction of the self-acting process of generating the explosive material confirmed the investigators' report. However, other materials at the incident site could have influenced the final outcome too. The lab-recreated explosion of a mixture of AN and molten plastic partially confirmed the report's thesis. [ABSTRACT FROM AUTHOR]