Increasing the burning rate through energetic compound tuning: Hybrids of the furazan and [1,2,4]triazolo[4,3-b][1,2,4,5]tetrazine ring systems

Abstract

Combustion behavior, flame structure, and thermal decomposition of hybrid compounds based on tetrazine, triazole and furazan rings have been described. It has been found that the introduction of [1,2,4]triazolo[4,3-b][1,2,4,5] tetrazine core into the molecules of energetic materials allows obtaining energetic hybrid compounds with combustion rates greater than those of common explosive HMX and RDX. These hybrids have good thermal stability, which depends on the substituent at the furazan ring, and not on the triazolotetrazine core. Combustion with thermocouple-aided studies has shown that all triazolotetrazine hybrids are nonvolatile and have high burning surface temperatures which cause their condensed-phase combustion mechanism. Based on the condensed-phase combustion model, the constants of the leading combustion reactions were determined. It turned out that the burning rates of nitrogen-rich compounds of this study are controlled by the decomposition kinetics at surface temperature. It is shown that the two-stage decomposition of substances leads to the appearance of two regions in the burning rate-pressure dependences that related to each other by the instability region. The incorporation of the triazolotetrazine moiety into an energetic compound is a promising way to design new propellant components with high burning rates and attractive performance.