The mechanical response of micron-sized molecular crystals

Abstract

Microstructures and corresponding properties of compacted powders ultimately depend on the mechanical response of individual particles. In principle, computational simulations can predict the results of powder compaction processes, but the selection of appropriate models for both particle–particle interactions and particle deformations across all relevant length scales remain nontrivial tasks, especially in material systems lacking detailed mechanical property information. The work presented here addresses these issues by conducting uniaxial compressions in situ inside of a scanning electron microscope to characterize the mechanical response of individual micron-sized particles of a molecular crystal, hexanitrohexaazaisowurtzitane (CL-20). This experimental approach enabled the collection of quantitative force and displacement data alongside simultaneous imaging to capture morphology changes. The results reveal information about elastic deformation, yield, plastic deformation, creep, and fracture phenomena. Accordingly, this work demonstrates a generalizable approach for assessing the mechanical response of individual micron-sized molecular crystal particles and utilizing those responses in particle-level models. Graphic abstract

Recent Advances in Nanomechanical Measurements and Their Application for Pharmaceutical Crystals

“…; therefore it is desirable to develop a genuine mechanical property of composites involved in formulation. To understand how individual particles compress or fracture, the indentation based microcompression tests can be utilized. − A flat punch or a large conospherical indenter has been used for such measurements. Along with indentation, having a complementary imaging technique such as optical or electron microscope facilitates proper sample–particle alignments and one can also visualize how the particles deform or fracture in real-time .…”

Mechanical stimulation of energetic materials at the nanoscale

“…Recently, in situ nanoindentation experiments with simultaneous SEM imaging were performed on micron-sized particles and thin films of PETN and CL-20, providing information on both the elastic and plastic behavior of particles, as well as on their fracture behaviour. 27,28 The present paper aims to extend the analysis of the mechanical stimulation of EMs at the nanoscale by considering the effects of humidity and the chemical structure on the impact and friction responses. To assure the general applicability of the obtained results, a diverse range of energetic compounds is considered.…”

“…Recently, in situ nanoindentation experiments with simultaneous SEM imaging were performed on micron-sized particles and thin films of PETN and CL-20, providing information on both the elastic and plastic behavior of particles, as well as on their fracture behaviour. 27,28…”