A review of small angle scattering, neutron reflection, and neutron diffraction techniques for microstructural characterization of polymer-bonded explosives

To better understand the structure-activity relationship and enhance the overall performance of polymer-bonded explosives (PBXs), the neutron and X-ray scattering techniques, which utilize neutron or X-ray radiation as probes, are unique and useful methods for quantifying the inherent hierarchical microstructures and components of PBXs. This review focuses on a series of scattering techniques and their typical applications in PBXs and includes a brief introduction of large neutron and X-ray scientific facilities in China. It describes the basic principles, instrumentation, sample environment, and empirical approaches of small-angle scattering (SAS), neutron reflection (NR), and neutron diffraction (ND). Additionally, it reviews common applications of these scattering techniques in the fields of PBXs. Combining the scattering techniques with complementary methods yields several valuable parameters that account for the microstructural features of PBXs. The combination can be used to establish multi-scale structure-activity relationships of PBXs and optimize the preparation process, numerical simulations, and performance prediction of PBXs. More efforts should be made to (1) gather the comprehensive multi-scale microstructural parameters for certain PBXs and add them to corresponding characteristic databases; (2) further investigate the dependence of the microstructural features on the preparation conditions of PBXs; (3) establish multi-factor correlations between the multi-scale microstructural features and the multiple performances obtained from experiments; (4) incorporate the microstructural parameters into various theoretical computational models.