Four series of TNT based melt cast explosives were prepared by mixing RDX, CL‐20, FOX‐7, and TKX‐50 with TNT in different mass ratios. The compatibility of these composition explosives was evaluated ...by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) according to the STANAG 4147 standard. Furthermore, the DSC and TGA data were also used to calculate the activation energies by the Kissinger and Ozawa methods. The experimental results indicated that the TNT/FOX‐7 composition explosives had good compatibility, whereas the TNT/CL‐20 composition explosives had poor compatibility. The TNT/RDX and TNT/TKX‐50 composition explosives at the mass ratios of 50 : 50, 40 : 60, 30 : 70, 20 : 80 and 10 : 90 had good compatibility. Furthermore, the decomposition activation energy of TNT/FOX‐7 composition explosives increased with increasing FOX‐7 content. Under the compatible condition, the decomposition activation energy of TNT/RDX composition explosives also increased with increasing RDX content, but the decomposition activation energy of TNT/TKX‐50 composition explosives decreased with increasing TKX‐50 content.
Traditional primary explosives often contain heavy metals, especially toxic lead, such as lead azide (LA) and lead styphnate (LS) that can cause environmental pollution problems. Copper(I) ...5‐nitrotetrazolate (DBX‐1) is a green primary explosive without toxic heavy metals, which is considered as one of the most promising alternatives to LA. DBX‐1 is usually synthesized from sodium 5‐nitrotetrazolate dihydrate (NaNT ⋅ 2H2O) and copper(I) chloride (CuCl). However, most of the synthesized products are irregular flakes with poor flowability, which affects the loadability. In this study, dextrin was used as a crystal shape modifier to improve the morphology of the synthesized product. Taguchi analysis method was used to determine the optimal experimental conditions for obtaining the spherical DBX‐1 with smaller particle size. The synthesized products were characterized by SEM, FTIR, UV‐Vis, STA TG‐DSC and VST, and their sensitivity was determined by BAM fallhammer, BAM friction tester and electrostatic spark sensitivity tester. The experiment results showed that the optimal combination of synthesis parameters was the NaNT ⋅ 2H2O concentration of 4.4 wt.%, the reaction temperature of 100 °C, the reaction time of 75 min and the additional dextrin solution of 5.0 mL. The average particle size of the synthesized spherical DBX‐1 was 33.0 μm. The decomposition activation energy was calculated by Kissinger method and Ozawa method to be 178.5 and 178.8 kJ/mol, respectively. The compound had good chemical stability. In addition, the sensitivity of spherical DBX‐1 was lower compared to that of flaky DBX‐1 and LA.
Since the early 20th century, lead azide (LA) has been commonly used as a primary explosive. However, lead pollution in the air and soil has attracted more and more attention, particularly in ...military training grounds and shooting ranges. Copper(I) 5‐nitrotetrazolate (DBX‐1) is considered as one of the most promising alternatives to LA. DBX‐1 is typically prepared from sodium 5‐nitrotetrazolate dihydrate NaNT(H2O)2 and copper(I) chloride (CuCl). But little is known about its optimal synthesis parameters. In addition, NaNT(H2O)2 is not commercially available. In this study, NaNT(H2O)2 was prepared by ourselves. Taguchi's experimental design method was used to determine the optimal experimental conditions for obtaining the maximum yield of DBX‐1. The synthesized NaNT(H2O)2 and DBX‐1 were identified by means of SEM, NMR, FTIR, EA, UV‐Vis and STA TG‐DSC, and the sensitivity of DBX‐1 was determined using BAM fallhammer, BAM friction tester and electrostatic spark sensitivity tester. The experimental results indicated that the optimal synthesis parameters of DBX‐1 were as follows: the reaction temperature was 100 °C, the reaction time was 30 min, the concentration of NaNT(H2O)2 was 0.075 wt.% and the molar ratio of NaNT(H2O)2 to CuCl was 1.15, and then the maximum yield after purification could reach 72.2 %. The decomposition activation energies of DBX‐1 calculated by Kissinger and Ozawa methods were 178.6 and 179.0 kJ/mol, respectively. In addition, the impact sensitivity, friction sensitivity and electrostatic spark sensitivity of DBX‐1 were 51 mJ, 0.4 N and 7.3 mJ, respectively, which were almost the same as those for LA.
This study pioneeringly dealt with the weighting analysis on activation energy (Ea) values from four series of TNT based high explosives (HEs) by using grey entropy model, initially constructing an ...innovative approach combining with the “Grey System Theory” entropy model and DSC/TGA experimentally-derived thermal analysis parameters for their process safety assessment and thermal stability influence evaluation. Herein, thermal analysis for these energetic samples of the HEs above which have each 10 mass% interval increased from 0 to 100 mass% contents of RDX, FOX-7 CL-20 and TKX-50 mixing with TNT to form four series of TNT based melt-cast explosives was experimentally conducted by DSC (differential scanning calorimetry) and TGA (thermogravimetry) under each 1, 2, 5 and 10 ℃ min
−1
heating rate. Their various Ea values, which were then calculated both by Kissinger and Ozawa methods in accordance with the above experimentally-derived thermal analysis data, were subsequently selected as an important indicator for the further weighting analysis and thermal stability evaluations via the grey entropy model toolbox feasibly in this study. The whole thermal stability influence under the various Ea weighting analyses, i.e., the individual “weighting value” along with the different RDX/FOX-7/CL-20/TKX-50 components added inside the TNT based melt-cast explosives were significantly explored and compared with quantitative consequences: TNT/FOX-7 (0.3002) > TNT/RDX (0.2347) > TNT/TKX-50 (0.2342) > TNT/CL-20 (0.2310) by Kissinger method; as well as the same order of TNT/FOX-7 (0.2980) > TNT/RDX (0.2352) > TNT/TKX-50 (0.2348) > TNT/CL-20 (0.2319) by Ozawa method, respectively. This shows that the “TNT/FOX-7” composition all exhibited the most thermal stability among the other compositions, demonstrating that the higher the “weighting value” of Ea properties for an explosive composition, the more thermal stable would be. Through our pioneering connection of the thermodynamic analysis and grey entropy weighting analysis on the Ea values in this study for process safety thermal stability assessment, the outcome could lead to a more comprehensive and broader understanding when such these energetic explosive substances were used. Particularly, this study could positively provide a useful decision-making suggestion associated with the relevant selections and applications of TNT based HEs or their formulations, contributing to the further developing of the burgeoning energetic materials both with thermal stability and energy performance not only in practical petrochemical industrials but also for the national defense military purpose worldwide.
Traditional primary explosives are usually heavy metal salts, especially salts of lead, such as lead azide (LA) and lead styphnate (LS), which can cause environmental pollution problems. The ...potassium salt of 4,6‐dinitrobenzofuroxan (KDNBF) has attracted more and more attention due to its advantages of no heavy metal pollution to the environment and appropriate sensitivity. There are many reports on the thermal properties and applications of KDNBF, but few reports on the morphological properties. In addition, little is known about the optimal synthesis conditions of KDNBF with different morphologies in the preparation process. In this study, Taguchi's experimental design method was used to determine the optimal experimental conditions for obtaining the maximum yields of KDNBF with different morphologies. The synthesized KDNBF was identified by means of SEM, NMR, FTIR, EA, and TG‐DSC, and its sensitivity was measured using BAM fallhammer, BAM friction tester, and electrostatic spark sensitivity tester. The experimental results indicated that the maximum yields of flaky and spherical KDNBFs could reach 85.6 % and 82.6 % after purification under the optimal experimental condition, respectively. The spherical KDNBF powder had a relatively denser structure than the flaky KDNBF powder. The thermal analyses showed that the activation energies of the decomposition reaction of the flaky and spherical KDNBF powders calculated by the Kissinger method were 171.5 and 188.5 kJ mol−1, respectively, and the Ozawa method were 170.7 and 186.9 kJ mol−1, respectively. The thermal stability of spherical KDNBF powder was higher than that of flaky KDNBF powder. In addition, the sensitivity tests showed that the spherical KDNBF powder was less sensitive than the flaky KDNBF powder.
The main aim of this study is to develop the vacuum pour‐casting process of the red phosphorus smoke agents. The typical composition of MK 58 marine location marker prepared by tamp‐casting process ...is red phosphorus (RP)/magnesium (Mg)/manganese dioxide (MnO2)/zinc oxide (ZnO)/epoxy resin (ER), which was selected as the original formula. Epoxy resin (ER) was replaced by hydroxyl terminated polybutadiene (HTPB) as the binder. First of all, simultaneous differential scanning calorimetry‐thermogravimetric analysis (STA DSC‐TGA) and vacuum stability tester (VST) were used to analyze the thermochemical characteristics, stability and chemical compatibility of the formula. Afterwards, Taguchi's experimental design method was used to design nine experimental conditions by way of orthogonal array with four control factors and three levels, and the scaled‐down smoke pellets were prepared using the vacuum pour‐casting method. The combustion phenomenon of these smoke pellets was recorded by the visual‐image capture system, and the flame temperature was measured by the temperature measurement system. The burning rate was chosen as the quality characteristic to analyze the optimal parameter combination of minimum burning rate. In addition, scanning electron microscopy coupled with energy dispersive spectroscopy (SEM‐EDS), tensile testing machine (TTM) and hardness tester (HT) were employed to observe the uniformity of the composition distribution in the pellet and to measure the mechanical strength and hardness of the pellets. Smoke density test chamber (SDTC) was used to measure the specific optical density of smoke generated by RP smoke agent. Finally, the operating conditions of the optimal parameter combination determined by Taguchi method were used to prepare the full‐size smoke candle, and its burning performance was verified and the feasibility of the vacuum pour‐casting technology was evaluated. The experimental results indicated that the optimal combination of parameters was the RP mixture/HTPB mass ratio of 84 : 16, the NCO/OH ratio of IPDI to HTPB (R value) of 1.6, the additional DOA of 4.5 wt % and the curing temperature of 50 °C. The prepared scaled‐down smoke pellets had good stability, chemical compatibility, hardness, mechanical properties and burning smoke density. In addition, the burning time and performance of the full‐size smoke candles prepared by vacuum pour‐casting technology also met the requirements.
4,6‐Dinitrobenzofuroxan (4,6‐DNBF) is explosive and can also be used as an important intermediate in the synthesis of other explosives. It can be prepared by nitrating benzofuroxan (BF) with mixed ...nitric/sulfuric acid. However, little is known about its optimal synthesis parameters in the preparation process. In this study, Taguchi's experimental design method was used to improve the yield of 4,6‐DNBF. A L9 (34) orthogonal array with four control factors and three levels of each control factor was used to design nine experimental conditions. The experimental data were transformed into a signal‐to‐noise (S/N) ratio to analyze and evaluate the experimental conditions of the optimal parameter combination for the maximum yield of 4,6‐DNBF. The verification results indicated that the optimal synthesis parameters were as follows: nitration temperature was 40 °C, mass ratio of BF to H2SO4, was 1 : 15, volume ratio of HNO3 to H2SO4 was 1 : 2.0 and reaction time was 4 hours, and then the maximum crude yield and the maximum yield after purification could reach 73.2 % and 49.0 %, respectively. Furthermore, the synthesized 4,6‐DNBF was identified by scanning electron microscopy (SEM), nuclear magnetic resonance spectrometer (NMR), Fourier transform infrared spectrometer (FTIR), elemental analyzer (EA), ultraviolet‐visible spectrometer (UV‐Vis) and thermogravimetry‐differential scanning calorimetry (TG‐DSC), and its sensitivity was determined using BAM fallhammer, BAM friction tester, and electrostatic spark sensitivity tester.
The solubility of solid active pharmaceutical ingredients in supercritical fluids is a major thermodynamic criterion for selection and screening of microparticle generation processes. To develop an ...efficient method for solubility prediction, a solution model was adopted to establish the correlations of the solid solubilities of six sulfonamides in supercritical CO2. The model was capable of determining solubility correlations. Accordingly, it was attempted to simplify and generalize the model, yielding a predictive solution model, which provided order‐consistent solubility predictions. A case study for model extrapolation was conducted. After understanding the mechanisms underlying the solubility of sulfonamides, the rapid expansion of supercritical solutions (RESS) process was applied to produce microparticles of p‐toluenesulfonamide, an anticancer drug. The effects of RESS process parameters were investigated.
A predictive solution model was developed to predict the solid solubility of sulfonamides in supercritical CO2. Microparticles of p‐toluenesulfonamide, an anticancer drug, with a mean size of 1.09 μm were successfully produced through an organic solvent‐free rapid expansion of supercritical solutions process. The effects of rapid expansion of supercritical solutions process parameters were evaluated.
This study is focused on the micronization of p-toluenesulfonamide (p-TSA) using the rapid expansion of supercritical solution (RESS) process. Taguchi’s experimental design method was applied to ...determine the optimum operating conditions. L9(34) orthogonal array with four control factors and three levels of each control factor was used to design nine experimental conditions. Four control factors were selected, including extraction temperature, extraction pressure, pre-expansion temperature, and post-expansion temperature. The particle size and morphology of the prepared samples were observed by scanning electron microscopy (SEM). In addition, Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) were employed to compare the differences between the raw and micronized p-TSA particles. The experimental and analytical results indicated that the extraction temperature was the most significant factor for the micronization of p-TSA in the RESS process, and the optimal operating conditions were at an extraction temperature of 50 °C, an extraction pressure of 220 MPa, a pre-expansion temperature of 220 °C, and a post-expansion temperature of 30 °C. The p-TSA particles were micronized from the original average size of 294.8 μm to the smallest average size of 1.1 μm at the optimal RESS process conditions. Furthermore, the physicochemical characteristics of p-TSA did not differ significantly before and after recrystallization.
In this study, the solventing‐out recrystallization method was applied to prepare insensitive and spherical high bulk density nitroguanidine (NQ). Experiments were performed at various operating ...conditions by using N‐methyl‐pyrrolidone (NMP) and acetone as solvent and antisolvent, respectively. The effects of different operating parameters such as NQ/NMP ratio, amount of acetone used, crystallization temperature, stirring speed and stirring time were investigated. The particle size and morphology of the prepared NQ crystals were observed by scanning electron microscopy (SEM), the bulk density was measured by the Archimedes’ method and the impact sensitivity was determined by fall hammer method. The experimental results showed that the solventing‐out recrystallization method could be used to prepare spherical high bulk density NQ with a narrow particle size distribution and the particle size could be controlled by changing the operating conditions. The bulk density of these spherical NQ particles was found to be in the range of 0.94–0.97 g cm−3, which is higher than that of needle‐shaped NQ particles, and they became less sensitive towards impact.
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