Crystal structure and morphology of β-HMX in acetone: A molecular dynamics simulation and experimental study

Size, Morphology and Crystallinity Control Strategy of Ultrafine HMX by Microfluidic Platform

The crystal structure has a great influence on mechanical sensitivity and detonation performance of energetic materials. An efficient microfluidic platform was applied for size, morphology, and crystallinity controllable preparation of ultrafine HMX. The microfluidic platform has good mixing performance, quick response, and less reagent consumption. The ultrafine γ-HMX was first prepared at room temperature by microfluidic strategy, and the crystal type can be controlled accurately by adjusting the process parameters. With the increase in flow ratio, the particle size decreases gradually, and the crystal type changed from β-HMX to γ-HMX. Thermal behavior of ultrafine HMX shows that γ→δ is easier than β→δ, and the phase stability of HMX is β > γ > δ. Furthermore, the ultrafine β-HMX has higher thermal stability and energy release efficiency than that of raw HMX. The ultrafine HMX prepared by microfluidic not only has uniform morphology and narrow particle size distribution, but also exhibits high density and low sensitivity. This study provides a safe, facile, and efficient way of controlling particle size, morphology, and crystallinity of ultrafine HMX.

An experimental and theoretical study on the growth of plate-like β-HMX crystals in the hydroxylated interlayer space

Plate-like β-HMX crystals are grown in the hydroxylated interlayer space using a crystallization technique combining the cooling crystallization and solvent-antisolvent methods. The obtained crystals have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The experimental results indicate that the most morphologically important face of the plate-like β-HMX crystals is the (011) face adopting a layer-by-layer growth mode. Meanwhile, molecular dynamics (MD) simulations were performed to study the crystal morphology in HMX crystal growth in the hydroxylated interlayer space based on a modified attachment energy (MAE) model. The calculated results show that the major face is the (011) face and the interaction energies between the crystal face and the hydroxylated interlayer are in the order of (011) > (110) > (020), which agree well with the experimental results above.

Crystal morphology prediction of energetic materials grown from solution: insights into the accurate calculation of attachment energies

Reasonable modifications to the attachment energy model were made for accurately predicting the crystal growth morphology of energetic materials in solution.

Significance of crystal habit sphericity in the determination of the impact sensitivity of bistetrazole-based energetic salts

The effect of crystal habit sphericity (Ψ) on impact sensitivity is described quantitatively. The developed empirical function (Ω), which includes five quantities obtained from first-principles calculations, correlates well with the experimentally measured impact sensitivities of 20 crystalline energetic salts based on 5,5′-bistetrazole derivatives.