Thermochemical properties of nanometer CL-20 and PETN fabricated using a mechanical milling method

Abstract

2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and pentaerythritol tetranitrate (PETN), with mean sizes of 73.8 nm and 267.7 nm, respectively, were fabricated on a high-energy ball-mill. Scanning electron microscope (SEM) analysis was used to image the micron-scale morphology of nano-explosives, and the particle size distribution was calculated using the statistics of individual particle sizes obtained from the SEM images. Analyses, such as X-ray diffractometer (XRD), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS), were also used to confirm whether the crystal phase, molecular structure, and surface elements changed after a long-term milling process. The results were as expected. Thermal analysis was performed at different heating rates. Parameters, such as the activation energy (ES), activation enthalpy (ΔH≠), activation free energy (ΔG≠), activation entropy (ΔS≠), and critical temperature of thermal explosion (Tb), were calculated to determine the decomposition courses of the explosives. Moreover, the thermal decomposition mechanisms of nano CL-20 and nano PETN were investigated using thermal-infrared spectrometry online (DSC-IR) analysis, by which their gas products were also detected. The results indicated that nano CL-20 decomposed to CO2 and N2O and that nano PETN decayed to NO2, which implied a remarkable difference between the decomposition mechanisms of the two explosives. In addition, the mechanical sensitivities of CL-20 and PETN were tested, and the results revealed that nano-explosives were more insensitive than raw ones, and the possible mechanism for this was discussed. Thermal sensitivity was also investigated with a 5 s bursting point test, from which the 5 s bursting point (T5s) and the activation of the deflagration were obtained.

Laser‐Ignited Relay‐Domino‐Like Reactions in Graphene Oxide/CL‐20 Films for High‐Temperature Pulse Preparation of Bi‐Layered Photothermal Membranes

“…Solution processing is one of the powerful techniques for handling energetic materials due to its uniform mixing ability and devoid of hazard . In the process, nonenergetic surfactants and/or binders are usually required to form stable suspensions, which may bring negative effects to the performance of the energetic materials.…”

Characteristics and properties of nitrocellulose/glycidyl azide polymer/2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane nanocomposites synthesized using a sol–gel supercritical method

“…Despite this, NC/GAP/CL-20 nanocomposite is remarkably more insensitive than raw CL-20. The mechanical sensitivities of raw CL-20 are shown in the study by Song et al 31 In the nanocomposites, CL-20 nanoparticles are embedded in the NC/GAP matrix. The matrix plays the roles of protection and buffer when the external impact or friction stimulus acts on nanocomposites.…”

Preparation and Characterization of Spherical Submicron CL-20 by Siphon Spray Refinement

“…The mechanical sensitivity of CL-20 explosives is reduced by means of refinement. The main methods commonly used include mechanical milling [2][3][4], chemical recrystallization [5,6], spray drying [7,8], and supercritical fluid recrystallization [9][10][11]. Wang et al [12] used a gas-phase antisolvent method (GAS) prepared nano-HNIW.…”