Acceleration of δ- to β-HMX-D8 Phase Retransformation with D₂O and Intergranular Strain Evolution in a HMX-Based Polymer-Bonded Explosive

Abstract

3,5,3,5, is one of the most widely used explosives. Problems about phase state and unrecoverable damage are significant in the application of HMX and HMX-based polymer-bonded explosive (PBX). Recently, the acceleration of δto β-HMX retransformation in humid atmosphere was reported. However, the function of water was not well understood. In this paper, we studied the mixed phase during δto β-HMX-d8 retransformation with neutron diffraction. Evidence of γ-HMX-d8 is specially focused to estimate whether the hydrated phase is part of the δto βphase retransformation. Besides, in situ high-pressure neutron diffraction of HMX-based PBX was performed to study the evolution of intergranular strains in special structures such as twin plane, cleavage planes, and slip systems. We observed an abnormal release of strain on certain planes under applied pressure which had not been reported. This abnormal phenomenon was considered to explain the formation of microcracks in HMX.

Phase Confirmation and Equation of State of β-HMX under 40 GPa

“…Apart from chemical components, crystal properties, including phase structures, grain sizes, and surface and internal defects, are known to have a significant influence on the mechanical strength, sensitivity, and stability of high explosives. − HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) is an eight-membered heterocyclic high-energy explosive that has been widely used for military weapons, aerospace applications, and modern industrial applications − because of its characteristics of high energy density, good thermal stability, high detonation performance, and product cleanliness. By controlling the crystallization rate in the solution, we can observe four crystal structures, including three pure crystallization phases of α, β, and γ and a hydrate γ structure, at ambient conditions. − The β phase is the most thermodynamically stable polymorph that has the highest density and is the only one used in weapons.…”

Synthesis and Effects of Two Novel Rare-Earth Energetic Complexes on Thermal Decomposition of Cyclotetramethylene Tetranitramine (HMX)

“…Furthermore, the formed fresh metal oxides can also adsorb more pyrolysis products of HMX and lead to the release of the adsorption heat [41]. (2) The main gaseous products of HMX are CH 2 O, NO 2 , CO 2 , NO, CO, and N 2 O [42][43][44]. It is noted that the thermal decomposition products of HMX are similar to those of automobile exhaust.…”

“…Nitrate ester plasticized polyether (NEPE) propellant is a new type of crosslinked, high-energy, solid propellant which uses polyether polyurethane as a binder, nitrate esters as plasticizers, and is filled with a large amount of the high-energy oxidant, cyclotetramethylene tetranitramine (HMX) [1][2][3]. It also contains a combustion agent, stabilizer, and combustion promoter [4].…”

“…H: the heat release of HMX or a mixed system 2. ∆H: actual added heat value of the system with complexes 1 to 5 3.…”