Density functional theory studies of effects of boron replacement on the structure and property of RDX and HMX

Abstract

In this study, based on two model nitramine compounds hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5, 7-tetrazocine (HMX), two series of new energetic molecules were designed by replacing carbon atoms in the ring with different amounts of boron atoms, their structures and performances were investigated theoretically by the density functional theory method. The results showed that the boron replacement could affect the molecular shape and electronic structure of RDX and HMX greatly, and then would do harm to the main performance like the heat of formation, density, and sensitivity. However, the compound RDX-B2 is an exception; it was formed by replacing two boron atoms into the system of RDX and has the symmetric boat-like structure. Its oxygen balance (4.9%), density (1.91 g/cm 3), detonation velocity (8.85 km/s), and detonation pressure (36.9 GPa) are all higher than RDX. Furthermore, RDX-B2 has shorter and stronger N NO 2 bonds than RDX, making it possesses lower sensitivity (45 cm) and better thermal stability (the bond dissociation energy for the N NO 2 bond is 204.7 kJ/mol) than RDX. Besides, RDX-B1 and HMX-B4 also have good overall performance; these three new molecules may be regarded as a new potential candidate for high energy density compounds.

The Effects of BTTN, TMETN and DEGDN Molecules on the Explosion Properties of PETN Molecule

“…The presence of PETN in the new designed molecules increased the heat of detonation tremendously as seen from Table 3. Similar to the studies in the literature [30,[36][37][38], it is seen that the explosion heat values increase by changing the substitution groups of energetic materials or adding new groups. This means that the new energetic materials obtained will generate more heat compared to the original explosives.…”

“…Consequently, relations in the second column of Table1 have been employed in the calculations. Wu et al [30] developed two series of novel energetic molecules by substituting carbon atoms in the rings of RDX and HMX compounds with varying quantities of boron atoms, and their performance was studied theoretically using the density functional theory approach (DFT-B3LYP 6-31G (d, p) level). The findings revealed that features including electrical structure, formation heat, density, and sensitivity may all be altered.…”