The influence of the thermo-oxidative aging semi-crystalline polyethylene terephthalate process on the thermal and mechanical properties was analysed in the article. For this purpose, PET was aged at 140 °C for 21, 35 and 56 days. The research showed that as a result of aging, the amount of the crystalline phase increases by about 8%, which translates into the properties of the aged material. The glass transition and melt temperature of lamellar crystals formed during first and second crystallisation increase with aging. The mechanical properties of the material were analysed in the temperature range of 25 to 75 °C. The tests were showing an increase in Young’s modulus and a decrease in elongation at the break as a result of aging. This phenomenon was particularly visible during tests at 75 °C and during the morphological observation of the fracture surface, where the fracture character of the material changes from ductile to brittle. In the case of the material aged for the longest time, the temperature has a negligible influence on the elongation at break.

The main aim of the work was the experimental and numerical analysis of the energy absorption/dissipation capabilities and failure mechanisms of novel hyper-elastic target material intended for ballistic applications including layers of composite armors, projectile catching systems and anti-ricochet layers covering walls of shooting ranges, ballistic tunnels, etc. Static and dynamic mechanical properties of the material were analyzed at both room and elevated temperatures ( $$40\div 80\,^{\circ }\hbox {C}$$40 ÷ 80 ∘ C ). Numerical models of the material and $$7.62\times 25$$7.62 × 25 mm FMJ projectile were defined. Simulations of the hyper-elastic target penetration with the projectile were carried out. The differences between the results obtained numerically and experimentally were determined (measured as a relative error) and were lower than 15% what testified about proper definition of the numerical models of the analyzed phenomenon components.

Formulations based on explosives with reduced vulnerability to mechanical stimuli and high thermal stability, e.g. nitrotriazolone, are used to produce insensitive munition. NTO has similar performance characteristics to commonly used explosives such as RDX and HMX, but is much less sensitive to accidental initiation due to heat, impact or spark. In order to forecast the thermal stability of explosives, as well as to determine for what period they can be safely operated, the accelerated ageing process is carried out, making it possible to predict changes in the initial properties of explosives during storage and to assess the impact of ageing on safety. This work aimed to obtain low-sensitive explosive compositions based on 3-Nitro-1,2,4-triazol-5-one and investigate the impact of accelerated ageing on their selected thermal and physicochemical properties. Two melt-cast compositions based on TNT and containing NTO were prepared and subjected to accelerated ageing. Samples were subjected to tests such as thermal analysis (including the kinetics of thermal decomposition), friction and impact sensitivity tests, as well as density measurements to determine the effect of ageing on, among others thermal properties, sensitivity to mechanical stimuli and density. As a result of accelerated ageing, all compositions changed colour. Sample submission to an ageing process did not adversely affect their sensitivity to friction and impact or thermal decomposition activation energy. Thermal decomposition of compositions is a complex process with an autocatalytic phase.

Pyrotechnic materials are one of the types of explosives which are used to manufacture products for military and civil purposes. These materials, in the event of improper storage or use contrary to their intended purpose, may work in an uncontrolled manner. In extreme cases, the phenomenon of a mass explosion involving the entire load, warehouse or transport vehicle may occur, which in turn may lead to significant losses in people or property. History cites many cases in which the explosion of spectacular pyrotechnic products, generally considered harmless, had catastrophic consequences for the life and health of many people. The risks associated with the use of pyrotechnic materials may result, among others, from: negligence on the part of producers, or organizational local authorities, lack or failure to maintain an appropriate level of security by sellers, organizers of mass events and users themselves. Due to the amount of storage in one place, pyrotechnic materials pose a particularly high risk in the places of production and storage. Over the years, there have been many disasters related to the accidental initiation of energetic semi-finished or finished products. This article describes accidents related to the activation of pyrotechnic materials in Poland and abroad. Methods for determining the degree of hazard posed by dangerous goods and examples of the Test Series 6 carried out for pyrotechnic articles are also presented.