Abstract
Premix membrane emulsification is a quick and efficient method to prepare emulsion. Pre-emulsion was prepared by dissolving 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and cellulose acetate butyrate (CAB) in ethyl acetate, and the mixture was added to an aqueous solution containing a surfactant. Then, the droplet uniform emulsion through the transmembrane was formed. The composites with the core–shell structure were obtained after evaporating the solvent. The results displayed that the morphological structure of CL-20 based composite could change from the dumbbell-shaped structure to spherical structure with an increase in the CAB content. Based on the impact sensitivity and thermal properties, the composite enhanced the safety. Meanwhile, a remarkable enhancement in the decomposition peak temperature (Tp0) and the critical temperature of the explosion (Tb) at a relatively low content of CAB (3 wt. %, 5 wt. % and 10 wt. %) was also noted. This approach provides a faster way for the design and preparation of polymer composites.
Highlights
Due to the higher safety of nano-scale CL-20 particles in comparison to the larger ones, several methods were developed for the preparation of nano CL-20, such as mechanical ball milling,5 spraying an ethyl acetate solution containing CL-20 into an isooctane solvent,6 supercritical antisolvent (SAS) technique that was optimized by the Taguchi robust design,7 siphon ultrasonic-assisted spray method,8 ultrasound- and spray-assisted precipitation,9 and drowning-out crystallization.10 In particular, the emulsion method is a very efficient and safe way to reduce the size of CL-20; the nano-HNIW particles were fabricated from thermodynamic stable o/w microemulsion11–13 and had a narrow particle size distribution
Cellulose acetate butyrate (CAB) possesses good leveling and film-forming properties;21,22 it acts as a CL-20-coated binder23–25 and effectively improves the security of CL-20
The formation of the core–shell structure occurred due to the excellent film-forming property of cellulose acetate butyrate (CAB), which has the network structure to limit the growth of CL-20.26 Figures 3(a) and 3(b) show that the shape of the composite material is dumbbell, indicating that the emulsion system is affected by the formation of composites
Summary
2,4,6,8,10,12 - hexanitro - 2,4,6,8,10,12 - hexaazaisowurtzitane (HNIW), called CL-20, was first synthesized in 1987 by Nielsen. HNIW is considered as the most powerful cage-structured material with high-energy and high-density today, and it is potentially used in the military sector and industries. HNIW is considered as the most powerful cage-structured material with high-energy and high-density today, and it is potentially used in the military sector and industries It has four structural isomers (α-, β-, γ-, and ε-form of the crystal), and all of which can exist at normal temperature and pressure.. The emulsion method has been widely used for the preparation of mono-disperse inorganic spherical particles, such as nano-PCL particles.14 It rapidly agitates for a long time to become uniformly emulsified, the Shirasu porous glass (SPG) membrane emulsification method can solve the problem perfectly. Cellulose acetate butyrate (CAB) possesses good leveling and film-forming properties; it acts as a CL-20-coated binder and effectively improves the security of CL-20 In this experiment, the organic solvent CL-20 and CAB were used as the oil phase to prepare O/W emulsion, which was passed through the premix membrane emulsification to make a uniform emulsion. It is found that the premix membrane emulsification method has not been used to prepare energetic materials
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