Thermo-analytical study of cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5-d]imidazole (BCHMX) and 1,1-diamino-2,2-dinitroethene (FOX-7) in comparison with a plastic bonded explosive based on their mixture

Abstract

The thermal behavior and decompn. kinetics of a new plastic bonded explosive (PBX) based on mixt. of bicyclic nitramine, cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5-d]imidazole (BCHMX) with insensitive explosive, 1,1-diamino-2,2- dinitroethene (DADNE or FOX-7) bonded by polydimethylsiloxane (PDMS) binder (44/44/12 wt%) have been investigated. For comparison, the individual materials, FOX-7 and BCHMX in addn. to their mech. mixt. have been studied. Nonisothermal TG and DSC techniques were used and the decompn. kinetics were obtained by the isoconversional methods (Kissinger and modified Kissinger-Akahira-Sunose (KAS) methods). Scanning electron microscope (SEM) was used to study the morphol. changes of BCHMX and FOX-7 crystals after heating isothermally at 210 °C for 5 min. Regarding to the studied PBX, It was found that the mechanism of thermal degrdn. of both the individual explosives is changed; the decompn. of pure BCHMX was shifted in the mixt. and the second peak of the FOX- 7 was merged with the peak of decompn. of their PBX. The thermo-anal. study shows also certain instability of PDMS binder over 190 °C in presence of FOX-7 and decompn. of FOX-7 as a soln. in the degrdn. products of this binder in temp. region typical for thermal decompn. of BCHMX. Nevertheless, the PDMS matrix seems to be a good binder for this mixt., filled by BCHMX and FOX-7, due to its good thermal stability in temp. regions enterable for practical military applications.