At low temperatures, gun propellant grains may become brittle and this can lead to fracture or shatter of the grains during gun firing. Should this event occur then it will result in an increase in the burning surface of the propellant and will give rise to a change in ballistic performance. Also, if the resultant over pressure is sufficient, a breech failure may result. Understanding the propensity of a grain to fracture or shatter is therefore important in determining its safety in use. This document describes a test that may be used to derive knowledge and to quantify the physical behaviour of a gun propellant grain at the low temperatures at which fracture or shatter is most likely to occur.
The composites of certain nitramine type explosives, TETRYL, RDX and EDNA, with proton in vacuum have been considered within the constraints of density functional theory at the level of B3LYP/6-31++G(d,p) (restricted and unrestricted). The results indicate that unexpectedly hydrogen molecule production occurs by the interaction of proton and a hydrogen of CH3 (TETRYL) and CH2 (RDX and EDNA) groups. As a result, a carbocation is generated on the explosive molecules. Thereafter, TETRYL which potentially has many protonation sites were investigated in more detail in vacuum and aqueous conditions. The data reveals that the composite system (TETRYL+proton) is less stable than TETRYL protonated on nitramine NH or oxygen of the nitro groups.