Fireworks play a key role in major festivals and conventional celebrations worldwide. Gunpowder, an inherently hazardous material, is a key component of fireworks. Few studies have investigated the impact of storage duration on the chemical composition of fireworks. This study investigated the effects of storage duration and aging on the hazardous characteristics of gunpowder extracted from explosive sound-producing fireworks stored under normal conditions at ambient temperatures. Two conventional firework samples were analyzed: One sample manufactured in 2005 and the other in 2022. Both samples had been stored in a secure location since manufacture until analysis. Field emission- scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS) were used to examine aging-related microstructural and elemental changes. Minimum ignition temperature and minimum ignition energy (MIE) measurements were conducted. Simultaneous thermogravimetric analysis (STA) and advanced thermal analysis were performed to evaluate thermal hazard parameters and calculate apparent activation energy. FE-SEM and XPS revealed microstructural cracks and oxidation on the surface of the 2005 sample. The 2005 and 2022 samples had MIE values of 79 and 5 mJ, respectively, and ignition delay times of 180 and 60 ms, respectively. These results indicate that the older sample had a longer ignition delay time. Longer ignition delay times represent lower stability, a greater risk of harm, worse performance, and diminished safety. STA revealed a mass loss difference of 9.876% between the 2005 and 2022 samples. Thermokinetic analysis indicates that, compared with the 2022 sample, the 2005 sample had a lower apparent activation energy, which is inversely correlated with reactivity and positively correlated with thermal stability. These results confirm an association between storage duration and firework safety. Manufacturers and retailers should ensure proper firework storage conditions and storage duration. Humidity is the environmental factor most likely to affect the chemical composition of fireworks.
Yang et al. (Fri,) studied this question.