Preparation And Characterization Of CL-20-based High-energetic And Low-sensitive Exeplosives

In the fie ld of energetic materials, high e nergy and lo w s e nsit ivit y o f explosives are t he p urs uing go al o f re sea rc hers in re cent ye a rs. B ut t here is a n essentia l co ntradictio n e xis ted be tween t he c haract erizat ions o f e nergy a nd sa fe ty, whi le t he highe r t he e nergy, t he lo wer t he sa fety. W it h t he de velopment o f we apons, improvin g t he sa fe ty a nd e nvironmental a daptability o f e xplosives ha s becomes t he fo cus o f mo de r n we apons de velopment. C L-20 is o ne o f explosives wit h the high energy, high density, and good thermal stabilit y, b ut it s high s e nsit ivit y lead s to t he li mited applications o f C L-20. In order to improve the sensit ivit y of C L-20 while maintaining its high energy, in this thesis, based on the co- crystallization and coated technique, explo sive C L- 20 as major research object, ―wood explosive‖ TATB as insensit ive reagent, the C L-20 based high energetic and low sensit ive explosive s, C L- 20/TATB cocrystal and C L- 20&TATB coated composite, have been successfully prepared via the reasonable choice of solvent systems and crystallizat ion method. At the same time, the structure and performance of C L-20/TATB cocrystal and C L-20&TATB coated composite have been characterized through the various technologies. The ma in contents are as follows:(1) Preparation and characterizat ion of the C L- 20/TATB cocrystal: due to inso lub ilit y of TATB in majority of organic solvents, it is very difficult to prepare the cocystals of TATB. In this work, through a rapid nuc leation solvent/non- solvent process, a novel cocrystal explosive, C L-20/TATB, has been successful prepared. The SEM results indicate that the cocrystals are homogeneous with the average partic le size of about 3-5 μm, and their morphology is completely different from primary materials. XRD and Raman analyses confir m that the cocrystal has unique peak patterns wit h large difference from C L-20 and TATB. IR and Raman spectra suggest that there exist hydrogen- bonding interactions between C L-20 and TATB mo lecules. The densit y determination, the weight loss on one step and the only exothermic peak in thermal analysis curves furt her illustrate that C L-20/TATB cocrystal is a new substance instead of ind ividua l crys tallizat ion of C L-20 and TATB. In CL- 20/TATB cocrystal, the mo lar ratio of C L-20 and TATB is 3:1 determined by HPLC. Ther mal ana lys is and detonation parameters calculation s hows that the cocrystal has excellent ther mal stabilit y and high energy- release efficiency. Impact sensit ivit y test indicates that the sensit ivity of cocrystal is sufficient ly reduced relative to C L-20. For C L- 20/TATB cocrystal, its detonation performance is superior to HMX and impact sensit ivit y is almost the same wit h HMX.(2) Preparation and characterizat ion of the C L- 20&TATB coated composite : in order to improve the safety of sensit ive explosive C L-20 while ma intaining its high energy, in this work, we prepare d a C L- 20&TATB coated composite through a simp le and economic rapid nucleation ant isolvent crystallizat ion method. In this approach, duo to making use of strong ant isolve nt and temperature effects, TATB has nanocrystallizat ion and the submicron TATB particles(about 600 nm) were obtained starting from commercial TATB powders(the average partic le size of about 30 um). The SEM and XRD results indicate that submicron TATB particle s formed a compactly and uniformly coated layer on the C L-20 surfaces. The coverage was close to 100% under the TATB content of 14%. The TG- DSC impact sensit ivit y test results show that C L- 20&TATB coated composite exhib ited a good therma l stabilit y and lower sensit ivit y comparable to insensitive explosive LLM-105.