## 3 Results
Figure 2: DSC analysis of pure ammonium nitrate (AN), pure hard PVC (uPVC), and their mixture (20%), heat rate 10 \({}^{\circ}\)C/min. Enthalpy of the mixture decomposition process \(\Delta\)H\({}_{\rm A}\) = \(-1384\) J/g, \(\Delta\)H\({}_{\rm B}\) = \(-66\) J/g (values of **A** and **B** reactions are given in Table 1). from 20% to 8% resulted in a behavior change of a similar nature. The heat effect was much lower: \(-396\) J/g compared to \(-1384\) J/g for the higher polymer content. Moreover, the splitting of the decomposition reaction was clearly observed. The decomposition process was a multistep one. On the other hand, increasing the amount of PVC to 50% of the mixture mass caused a change in the course of the process observed with the DSC analysis. The decomposition process became explosive and single-step. A more-than-three-times-higher heat release rate was observed compared to the 20% AN/PVC mixture. The measured enthalpy of the reaction was lower than that of the 20% mixture and amounted to \(-880\) J/g. The difference between the temperature of the reaction's termination and its beginning was \(5.7\)\({}^{\circ}\)C, while in the case of the 8% and 20% mixtures the difference was over 30 \({}^{\circ}\)C. Due to the explosive nature of the decomposition of the mixture containing 50% polymer, it was decided to also analyze the mixture containing 75% polymer. The nature of the decomposition process was not changed in relation to the 50% mixture (Table 1). The initiation temperature of the reaction rose slightly to 250.3 \({}^{\circ}\)C. The enthalpy of the reaction decreased to \(-537\) J/g, and the rate of heat released increased more than four times (to 46.3 W/g). The course of the reaction itself was very similar and also indicated the explosive nature of the decomposition reaction (Figure 4). In the case of products made of PVC-P, the observations were similar to those of uPVC-made products. Their AN mixture containing 20% polymer also decomposed in several steps. Some differences were due to the different chemical composition compared to uPVC. In contrast to uPVC, the pure polymer content of PVC-P in the AN mixture can be up to about 50% lower due to the increased plasticizer content. For this reason, it was decided to choose a colorless material, since the addition of dyes, for example, ZnO or TiO\({}_{2}\), in colored uPVC and PVC-P products is typically 20-30%. In the case of a 20% PVC-P mixture with AN, the process was much gentler than in the case of uPVC. At temperatures above 190 \({}^{\circ}\)C, we observed the decomposition of the mixture, which accelerated significantly only at above 250 \({}^{\circ}\)C. However, in this case, in the measurement conditions we did not register the explosive nature of either the first or the second process. Stagnation enthalpy of the decomposition reaction was \(-1560\) J/g (Figure 5). Figure 4: DSC analysis of pure AN, pure soft PVC (PVC-P), and their mixture (20%), heat rate 10 \({}^{\circ}\)C/min. As in the case of uPVC, reducing the amount of material to 8% by mass reduced both the reaction initiation temperature (248.1 \({}^{\circ}\)C) and the reduction of its heat effect (\(-1265\) J/g). Moreover, similarly to the previous case, a splitting of the decomposition reaction was observed. In contrast to uPVC, increasing the amount of polymer in the mixture to 50% also resulted in a reduction of the heat effect to an even greater extent than in the case of the 8% mixture (\(-813.2\) J/g). In addition, a significant reduction in the reaction initiation temperature was observed, which, in this case, was 244 \({}^{\circ}\)C (Table 2). Summing up, for neither of the analyzed cases (range of tested mass concentrations) were typical explosive reactions observed. However, attention should be paid to the test conditions, as the tests were carried out in a way that minimized the pressure increase.