THE EFFECTS OF HIGH RELATIVE HUMIDITY AND TEMPERATURE ON THE BORON POTASSIUM NITRATE (BPN) PYROTECHNIC COMPOSITION

The behavior of a pyrotechnic mixture (PM) changes during its service life, and the changes may affect its performance and characteristics. Boron potassium nitrate (BPN) is one of the most widely used PMs so its aging behavior is critical and important. In general, PMs are sensitive to high temperatures as well as to humidity. The effects of accelerated aging under extreme temperature and relative humidity conditions on the physical and combustion properties of pellet form-BPN were investigated. BPN pellets were prepared in unpackaged and packaged configurations to assess the effects of packaging. Subsequently, they were subjected to accelerated aging under constant conditions and various levels of relative humidity (RH) at 60°C. The samples were kept in these RH conditions until the weight gain of any of the pellets reached an increase of 20%-30%, when the aging tests were stopped and the physical and performance properties of the samples were measured. The results show that 80% RH at 60°C was the extreme condition for both packaging configurations. These samples absorbed a high level of moisture compared to the other samples and as a result, the physical properties and performance of the samples were negatively affected. Also, the results indicate that the unpackaged configuration at 80% RH was affected more significantly than the packaged configuration at the same relative humidity. Hence, conductive bags protect the sample from moisture. The impact sensitivity of the BPN pellets was not affected at different RH conditions and packaging configurations.