No abstract

In this work, through a rapid nucleation solvent/non-solvent process, a novel CL-20/TATB cocrystal explosive has been successfully prepared with a detonation performance superior to HMX and an impact sensitivity almost the same as HMX.

Insensitive High Explosives (IHEs) have attracted considerable interest in the past three decades due to their potential application in various propellants and military warheads. 1À4 Exploration of the explosive of low impact sensitivity and high explosive performance is the fundamental problem in the energetic materials, which has not been solved yet. HMX, a sensitive explosive, is a typical highly energetic material that has been widely used in national defense industries since the 1940s. The explosion performance of HMX is high; however, it is sensitive to heat and shock. Meanwhile, TATB belongs to a class of IHEs that are insensitive or difficult to detonate. The unique high thermal stability and its resistance to physical shock are desirable properties of TATB in many applications. 5 Two methods are mainly developed to reduce the sensitivity of HMX, 6,7 one is the control of the crystal shape and quality of I-RDX (insensitive 1,3,5-trinitro-1,3,5 -triaza-cycrohexane) 8 and I-HMX, 6 and the other preparation of HMX-based plastic bonded explosive (PBX). I-RDX and I-HMX changed from a macroscopic shape and crystal quality of the crystals, but cocrystal explosive (CCE) will further improve at the molecular level. Under same circumstance, the explosion performance of PBX is reduced, whereas that of CCE remains unchanged.Novel approaches to reduce the sensitivity of HMX are now considered widely. Cocrystal technology 9À14 are so important for improving the solubility, bioavailability physical and chemical stability properties of drugs without changing their chemical structure that it is widely used for the pharmaceutical chemicals. 15À18 The cocrystal is generally accepted to be neutral complexes composed of two components bonded by hydrogen bonding, π-stacking, and Van der Waal's forces. 19,20 Hydrogen bond is essential for the structural stability of many important cocrystals. 21À24 Reports of CCE are currently very limited. Michael patented cocrystals of HMX and AP (ammonium perchlorate). 25 Zhou et al. studied on the cocrystallized explosive of urea nitrate and RDX. 26 While all of those works provide a preliminary exploration of CCE, there is still lack of the convincing characterization to confirm whether the cocrystal was formed. Our co-worker Wei et al. recently reported the theoretical designing calculation of cocrystal HMX/TATB (molar ratio 1:1) by molecular dynamics (MD) simulation. 27 The calculation indicates that the mechanical properties and stability of the explosive can be effectively improved.In this paper, we prepare a novel HMX/TATB (mass ratio 9:1 and its molar ratio is about 8:1) CCE with a so-called solvent/ nonsolvent (S/NS) process. The results demonstrate that the crystal quality and sensitivity of the prepared CCE are considerably improved compared with the HMX.

Mechanical properties of composites are strongly influenced by the quality of the fiber/matrix interface. The objective of this study was to evaluate the mechanical properties of polylactide (PLA) composites as a function of modification of sisal fiber with two different macromolecular coupling agents. Sisal fiber reinforced polylactide composites were prepared by injection molding, and the properties of composites were studied by static/dynamic mechanical analysis (DMA). The results from mechanical testing revealed that surface-treated sisal fiber reinforced composite offered superior mechanical properties compared to untreated fiber reinforced polylactide composite, which indicated that better adhesion between sisal fiber and PLA matrix was achieved. Scanning electron microscopy (SEM) investigations also showed that surface modifications improved the adhesion of the sisal fiber/polylactide matrix.