Formulation and Characterizations of Nanoenergetic Compositions with Improved Safety

Abstract

In order to improve the safety of energetic compositions, whether it has to be worked with less sensitive materials that are often less powerful or with high energetic materials crystals with improved purity and microstructure quality. A way to modify the crystal quality of an energetic material is to structure the matter on the nanoscale: the crystals size reduction should induce impurity modifications in the particles. That is one of the reasons why interest in nanoenergetic compositions that contain high energetic material (≥ 90 wt‐%) and an organic matrix (≤ 10 wt‐%) that takes part in constraining the explosive to organize itself on the nanoscale arose. The key point is to find or synthesize the matrix. In the course of this study, first ammonium perchlorate compositions structured on the nanoscale were synthesized (150 nm AP particles (80 wt‐%) dispersed in an organogel matrix (20 wt‐%)). The formulation process was based on the impregnation of porous organogels with a saturated aqueous solution of ammonium perchlorate followed by freeze drying. The overall composition had an oxygen balance equilibrated towards CO2. These AP nanocompositions show better safety behavior during combustion than there equivalent macrocompositions, while they burn more rapidly, with no degradation of their impact and thermal sensitivity properties. The formulation process of RDX nanocompositions is more complex as the solvent used is γ‐butyrolactone which can not be directly frozen dried. However, first RDX nanocompositions were formulated and characterized using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X‐ray powder diffraction, and drop weight impact. Lately compressions of these RDX compositions were performed, prior to gap‐test experiments.

Study on Thermal Behaviour of AP/LiBH4 Energetic System

“…Thermal explosion response was an incompatibility issue between LiBH 4 and AP and mainly due to the thermal reaction of AP. (3) There is a complex chemical reaction between LiBH 4 and AP. LiBH 4 is easily oxidized by H 2 O in the energetic system and AP will act as the oxidizer for the reducing gases released from LiBH 4 .…”

“…However, the direct preparation of single explosive is confronted with more and more technical difficulty. On the contrary, mixed explosive has proved a key approach to improve explosion energy by designing and exploring oxidant-fuel energetic systems, and represents an important research direction of weapon systems [1][2][3][4][5]. Owing to the strong reactivity and high combustion heat, metal hydrides attract great attention as candidates of fuel additives in energetic system for several decades.…”

Developments and challenges in the manufacturing, characterization and scale-up of energetic nanomaterials – A review

“…Using the sol-gel method, the following nanocomposite energetic materials have been reported in literature: AP in a resorcinol-formaldehyde (RF) matrix [47], CL-20/NC [33,34], AP/RF [35], AP/RDX/SiO2 [36], AP/SiO2 [48], RDX/AP in a matrix of phloroglucinol (P) and nitrophloroglucinol (NP) as precursors and formaldehyde as reagent [37], RDX/GAP [49] and NC/RDX/AP [50]. Instead of using liquid nitrogen in the cryogel method, Nie et al [38] used supercritical CO2 to prepare a nanocomposite of HMX/AP in an RF matrix.…”

The longstanding challenge of the nanocrystallization of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX)

“…An RDX/resorcinol formaldehyde (RF) nanocomposite has been synthesized [ 27 ] where 38 nm RDX crystallized in an RF aerogel matrix with a surface area of 551.5 m 2 /g (measurement taken without RDX). Wuillaume et al [ 28 ] trapped ammonium perchlorate (AP) and RDX in a mesoporous low-density energetic organogel. During the impact test, a negligible decrease of sensitivity was measured: 75 wt % RDX nanogels and macrogels had the same sensitivity and the 90 wt % nanogels are even more sensitive than their macroscopic counterparts.…”