Directional design of interface and thermal performance for CL-20 using hollow fiber embed in desensitizer membranes

The explosive/desensitizer interface is the key to the thermal safety of polymer bonded explosive (PBX). Herein, a structural bionics coating was designed and fabricated on the surface of CL-20 to enhance the thermal safety of CL-20-based PBX. The film was composed of hollow fiber@desensitizer and its performances were recorded by SEM, XPS, TG-DSC, XRD, mechanical sensitivity tester, slow cook-off tester and ignition tester, respectively. The morphology and surface performance showed that CL-20 was completely coated by composite film. Notably, the XRD results provide crucial safety assurance for the preparation process. The aqueous polyurethane emulsion (ATPU)@TiO₂ nanotube film endowed the T_p0 and T_b of CL-20 from 218.15℃ and 220.27℃ up to 228.38℃ and 230.92℃, respectively. Meanwhile, the thermal respond reaction of CL-20-based PBX charge occurred at more than 232℃ during slow cook-off heating. These results indicated that the thermal stability of CL-20 was significantly improved. Most importantly, the microcrystalline wax (MW)@multiwalled carbon nanotube (MNCNTs) film brought mechanical critical load of CL-20 from 60 N and 3.5 J to 288 N and 14.6 J, respectively. This improvement allows for the handling of composite explosives using conventional protocols. The ATPU@MNCNTs also increased friction critical load of CL-20 up to the level of WO₃/Al nanothermite (360 N). In ignition testing, the composite particle underwent rapid thermal decomposition, emitting yellow smoke without combustion. Among the particles, H-3# exhibited the slowest decomposition rate. These findings could offer valuable insights for the broad application of CL-20.