Theoretical insight into the acidity and cooperativity effect of the LLM-105∙(HNO3)2 system.

In order to reveal the nature of the acidity in explosive product, the acidities and cooperativity effects from the intermolecular H-bonding interactions in the LLM-105∙∙∙(HNO3)2 ternary systems were investigated at the B3LYP/6-311 + + G** and M062X/6-311 + + G** levels, with the integral equation formalism polarized continuum model (IEFPCM) based on the self-consistent-reaction-field. The results show that for the ternary systems, the intermolecular H-bonding interactions are stronger than those in the binary complexes, resulting in the lower [H+] concentrations and larger pKa1 values upon the ternary-complex formations. However, there is no obvious correlation between the acidities and cooperativity effects or APT charges of the H atoms involving the H-bonds. Surface electrostatic potential (ESP) and reduced density gradient are used to reveal the nature of the H-bond and acidity. Interestingly, the acidity is closely related to the ESPs of the H atom (VS,H) involving the intermolecular H-bond, but not to the statistical quantities. This is mainly because both acidity and VS,H are the local properties of system, whereas the cooperativity and statistical quantity of ESP are the global property.

Theoretical prediction of the impact sensitivities of energetic C-nitro compounds.

In order to design high-energetic and insensitive explosives, the frontier orbital energy gaps, surface electrostatic potentials, nitro group charges, bond dissociation energies (BDEs) of the C-NO2 trigger bonds, and intermolecular interactions obtained by the M06-2X/6-311++G(2d,p) method were quantitatively correlated with the experimental drop hammer potential energies of 10 typical C-nitro explosives. The changes of several information-theoretic quantities (ITQs) in the density functional reactivity theory were discussed upon the formation of complexes. The BDEs in the explosives with six-membered ring are larger than those with five-membered ring. The frontier orbital energy gaps of the compounds with benzene ring are larger than those with N-heterocycle. The models involving the intermolecular interaction energies and the energy gaps could be used to predict the impact sensitivity of the C-nitro explosives, while those involving ΔSS, ΔIF, and ΔSGBP are invalid. With the more and more ITQs, the further studies are needed to seek for a good correlation between impact sensitivity measurements and ITQs for the energetic C-nitro compounds. The origin of sensitivity was revealed by the reduced density gradient method.

[Monitoring of Curing Temperature of Pouring Explosive Based on Fiber Bragg Grating].

For the first time, we real time measured released reaction heat between the binder and the curing agent in the curing process of cast explosive using fiber Bragg grating. In order to obtain the temperature in the process of pouring explosive casting real time and accurately, we designed the temperature monitoring system based on fiber Bragg grating. Given the risk of explosive component, long curing time and the requirements of constant temperature, a suitable measurement method for direct real-time monitoring has not been found. In recent years, due to its superior characteristics, fiber Bragg grating is widely used in the field of communication and sensing. We will make the collected reflection wavelength to convert real-time temperature displaying, utilizing linear relationship between fiber Bragg grating and temperature. Through WDM technology, seven grating points are written in two optical fibers to measure at the same time, and distribution trend of explosives internal temperature can be displayed in real time by multi-point distributed measurement. The curved design of the sensor not only improves the connection between sensor and jumper, but also benefits to place in oven. The txt data is made to draw a graph using origin software, and the changes in temperature in the curing process are displayed intuitively. The results show that this method is simple and high-precision, and meets the testing requirements of curing temperature of explosives.

Degradation mechanism of 2,4,6-trinitrotoluene in supercritical water oxidation.

The 2,4,6-trinitrotoluene (TNT) is a potential carcinogens and TNT contaminated wastewater, which could not be effectively disposed with conventional treatments. The supercritical water oxidation (SCWO) to treat TNT contaminated wastewater was studied in this article. The TNT concentration in wastewater was measured by high-performance liquid chromatograph (HPLC) and the degraded intermediates were analyzed using GC-MS. The results showed that SCWO could degrade TNT efficiently in the presence of oxygen. The reaction temperature, pressure, residence time and oxygen excess were the main contributing factors in the process. The decomposition of TNT was accelerated as the temperature or residence time increased. At 550 degrees C, 24 MPa, 120 s and oxygen excess 300%, TNT removal rate could exceed 99.9%. Partial oxidation occured in SCWO without oxygen. It was concluded that supercritical water was a good solvent and had excellent oxidation capability in the existence of oxygen. The main intermediates of TNT during SCWO included toluene, 1,3,5-trinitrobenzene, nitrophenol, naphthalene, fluorenone, dibutyl phthalate, alkanes and several dimers based on the intermediate analysis. Some side reactions, such as coupled reaction, hydrolysis reaction and isomerization reaction may take place simultaneously when TNT was oxidized by SCWO.