Theoretical and experimental investigation into a eutectic system of 3,4-dinitropyrazole and 1-methyl-3,4,5-trinitropyrazole.

Eutectic mixtures of 3,4-dinitropyrazole (DNP) and 1-methyl-3,4,5-trinitropyrazole (MTNP) were investigated by theoretical and experimental methods. The mass ratio of DNP and MTNP ranged from 0:100 to 100:0. Melting points of the mixtures were predicted through observing the inflection point of a specific volume vs. temperature in molecular dynamics (MD) simulation. The results are in good agreement with experimental results obtained from the differential scanning calorimeter (DSC) study. The binding energy of a 50/50 DNP/MTNP eutectic mixture is lower than those of other mixtures, in accordance with the common sense that the melting point of materials is linked to the strength of intermolecular interactions. There are definitely hydrogen bonds and dispersion interactions between DNP and MTNP based on the analyses of interaction energy, atom in molecules (AIM), and reduced density gradient (RDG). The eutectic mixture would be encouraged to be used in melt-cast explosives because of the favorable sensitivity to heat and impact, great detonation performances, acceptable vacuum stability and excellent compatibility with high explosives. Graphical abstract The eutectic mixture of DNP and MTNP were investigated through molecular dynamics (MD) simulation and quantum chemistry calculations. The predicted melting points of mixtures are in good agreement with the experimental data. The eutectic mixture shows good stability.