Design a Cross-Linked Film Based on Cellulose Nanocrystals Doping for Enhancing the Interfacial Performance and Desensitization of CL-20

Despite the extensive researches on CL-20 crystals, the mechanical safety issues and process problems of CL-20 applications have not been studied in-depth. Herein, the cellulose nanocrystals (CNC) was doped in microcrystalline wax (MW), oxidized microcrystalline wax (OMW) and hydrogel (PPC) to design and fabricate the cross-linked CL-20 composites by simple water-suspension melting and freeze-drying methods. The composites were characterized by SEM, XPS, TG-DSC, XRD, mechanical sensitivity device and inclined chute tester. It is found that the CNC@OMW composite film exhibits excellent coating effect (99.96%) on CL-20 due to the cross-linking results. The Ea of CL-20 is increased from 190.92 to 388.71kJ/mol under the synergistic effect of the excellent compatibility between components and the compact coating structure of CNC@OMW. Additionally, the film enhances the Tp0 of CL-20 from 218.15 to 222.66 ℃ and Tb from 220.27 to 223.73 ℃, respectively. While, the PPC@CNC only promoted Ea, Tp0 and Tb of CL-20 to 292.89.71kJ/mol, 224.22 ℃ and 225.66 ℃, respectively. Besides, the XRD results confirms that three composite films dose not cause a transformation of the ε-CL-20 crystal phase. Most importantly, the cross-linked film brings mechanical sensitivity of CL-20 from 60N and 3.5J to a level of over 360N and 10.4J, comparable to WO3/Al nanothermite with 5wt% polyaniline (360N) and composite with 95wt% LLM-105 and 5wt% ternary (11-12J). This improvement enables the composite explosives to be handled using standard procedures. Furthermore, the ability of the particles to accumulate electrostatic charge after cross-linking coating is significantly reduced, and PVC is more suitable as the contact material of CL-20 and composite particles than copper for use in the transportation and packaging. These findings can serve as a reference for wide application of CL-20.