Decomposition Peak Research Articles

Synthesis, structure, and AP catalytic performance of two new 1D coordination polymers

Two 1D chain coordination polymers (CPs), [Co(DNDPA)(DMF)2] 1 and [Mn(DNDPA)(DMF)2] 2, were successfully synthesized (4,4′-dinitrodiphenic acid, DNDPA). Their structures were confirmed by single-crystal X-ray diffraction. Differential scanning calorimetry coupled with thermogravimetric analysis revealed that both CPs exhibit commendable thermal stability, with CP 1 and 2 decomposing at 368.9 °C and 375.5 °C, respectively. Non-isothermal kinetic studies confirmed that both CPs displayed significant catalytic activity for the decomposition of ammonium perchlorate (AP). In particular, CP 1 and 2 reduced the activation energy of AP from its intrinsic value to 100.5 kJ/mol and 127.45 kJ/mol, respectively, and its high-temperature decomposition peak to 354.3 °C and 327.7 °C, respectively. These findings underscore the potential of these CPs as effective catalysts for enhancing the combustion properties of AP.

The bimetallic 3,5-dinitrobenzoate composites: A flexible-synergistic catalysts for high-performance decomposition of ammonium perchlorate

Composites of metal complexes have catalytic effects on the thermal decomposition of ammonium perchlorate (AP), while the kinetics and mechanism studies of the processes are seldom mentioned. Here, composite microspheres of cupric 3,5-dinitrobenzoate and cobalt 3,5-dinitrobenzoate [(3,5-DNB)Cox•Cuy] were synthesized and employed to research the kinetics and mechanism of AP catalytic decomposition. The decomposition peak temperature of AP in the presence of the (3,5-DNB)Cox•Cuy microspheres decreased from 403 °C (pure AP) to 288 °C, and the released heat increased by 384.5–745.6 J/g. Notably, the (3,5-DNB)Cox•Cuy microspheres significantly improved the kinetic rate constant by 1.83–37.75 times. The (3,5-DNB)Cox•Cuy microspheres exhibited higher activity than their corresponding single components for the thermal decomposition of AP, indicating excellent synergistic effects and proposing a possible mechanism. Understanding the kinetics and mechanism of the catalytic process developed in this study could further improve the decomposition performance of AP.

The Impact of Activated Carbon–MexOy (Me = Bi, Mo, Zn) Additives on the Thermal Decomposition Kinetics of the Ammonium Nitrate–Magnesium–Nitrocellulose Composite

This research investigates the impact of additives such as activated carbon (AC) combined with metal oxides (Bi2O3, MoO3, and ZnO) on the thermal decomposition kinetics of ammonium nitrate (AN), magnesium (Mg), and nitrocellulose (NC) as a basic AN–Mg–NC composite. To study the thermal properties of the AN–Mg–NC composite with and without the AC–MexOy (Me = Bi, Mo, Zn) additive, a differential scanning calorimetry (DSC) analysis was conducted. The DSC results show that the AC–MexOy (Me = Bi, Mo, Zn) additive catalytically affects the basic AN–Mg–NC composite, lowering the peak decomposition temperature (Tmax) from 534.58 K (AN–Mg–NC) to 490.15 K (with the addition of AC), 490.76 K (with AC–Bi2O3), 492.17 K (with AC–MoO3), and 492.38 K (with AC–ZnO) at a heating rate of β equal to 5 K/min. Based on the DSC data, the activation energies (Ea) for the AN–Mg–NC, AN–Mg–NC–AC, and AN–Mg–NC–AC–MexOy (Me = Bi, Mo, Zn) composites were determined using the Kissinger method. The results suggest that incorporating AC and AC–MexOy (Me = Bi, Mo, Zn) additives reduce the decomposition temperatures and activation energies of the basic AN–Mg–NC composite. Specifically, Ea decreased from 99.02 kJ/mol (for AN–Mg–NC) to 93.63 kJ/mol (with addition of AC), 91.45 kJ/mol (with AC–Bi2O3), 91.65 kJ/mol (with AC–MoO3), and 91.76 kJ/mol (with AC–ZnO). These findings underscore the potential of using AC–MexOy (Me = Bi, Mo, Zn) as a catalytic additive to enhance the performance of AN–Mg–NC-based energetic materials, increasing their efficiency and reliability for use in solid propellants.

Study on Oxygen Balance Regulation of TKX‐50 Based on Emulsion Method

AbstractDuring the process of external work, the energy of the negative oxygen balanced 5,5′‐Bi‐tetrazolium‐1,1′dioxyhydroxylammonium salt (TKX‐50) is not fully released, resulting in low energy utilization efficiency and the generation of harmful gases that pollute the environment. Based on this, in order to adjust the oxygen balance of TKX‐50, nano TKX‐50/AP composites with positive, zero and negative oxygen balance were prepared by emulsion method. The morphology of nano TKX‐50/AP composite was similar to that of hedgehog‐like spherical‐like particles, with many dense pores formed on the surface, and the average particle size was about 30 μm. During the composite process, part of TKX‐50 reacted with AP to form 5,5′‐bistetrazole‐1,1′dioxidamide (ABTOX). The first thermal decomposition peak temperature of zero‐oxygen balance TKX‐50/AP composite was 236.0°C, which was slightly reduced compared with that of TKX‐50. The second thermal decomposition peak temperature was 275.1°C, which was 22.2°C higher than that of TKX‐50. The heat release of zero‐oxygen balance TKX‐50/AP composite reached 2206 J g−1, which increased by 35.9% compared to TKX‐50, and the energy utilization efficiency was also greatly improved. The drop height of 50% explosion probability (H50) of zero‐oxygen balance TKX‐50/AP composite was 63.5 cm, and the explosion probability of friction sensitivity was 72%. Compared with TKX‐50, it increased by 15.1 cm and decreased by 28%, respectively. The results showed that the mechanical safety performance of TKX‐50 had been improved.

Pyrolysis of Khat waste vs. Coal: Experimental and Aspen plus analysis

This study explores the potential of Khat waste as a biofuel through a detailed analysis of its physical properties and pyrolytic behavior, employing both laboratory and simulation techniques. Biomass, including Khat waste, is a valuable renewable energy source with potential applications in reducing waste and CO2 emissions, especially in rural areas of developing countries like Ethiopia. The physical properties of the Khat waste were thoroughly examined, including moisture content, ash, volatile matter (VM), fixed carbon (FC), and elemental composition. The apparent density of the pyrolyzed khat waste was found to be 0.9688 g/cm³. The TGA results showed a moisture loss of 6.7 %, volatile matter of 4.7 %, fixed carbon of 6.78 %, and ash content of 5.55 %. Notably, Khat waste exhibited unique thermal behavior with a downward shift in TG curves above 220 °C. DTGA identified three decomposition peaks: moisture evaporation at 100 °C, hemicellulose breakdown at 210 °C, and cellulose degradation at higher temperatures. Fourier Transform Infrared Spectroscopy (FTIR) provided insights into the functional groups present in Khat waste, including alkene functional groups and O-H bonds, which are crucial for biofuel properties. Simulation using Aspen Plus software modeled the pyrolysis process, highlighting how varying heating rates affect volatile matter and fixed carbon content. Increasing heating rates decreased volatile matter and moisture but increased fixed carbon content. These findings offer valuable insights for optimizing Khat waste as a biofuel, emphasizing the need for tailored pyrolysis conditions to enhance biofuel production efficiency.

Selective Conversion of Thermal Decomposition Products of Ammonium Perchlorate by Amorphous CoSnOx

The directional transformation of products in the multiphase decomposition process of ammonium perchlorate (AP) still faces significant challenges, one of which is the conversion of greenhouse gas N2O. Furthermore, additional elucidation of the structure and potential catalytic mechanisms of catalysts with high thermal stability is imperative for the aforementioned process. This study proposes a cobalt-based amorphous oxide with high thermal stability for catalysing the thermal decomposition of AP and achieving the transformation of catalytic products from N2O to NO (its derivatives). The results indicate that the type of catalytic decomposition products is related to the structural transformation of the catalyst, suggesting a synergistic oxidation mechanism by active oxygen and lattice oxygen. The peak decomposition temperature of AP has dropped to near the limit of 257.2 ° C, TG-IR test and MD simulation results indicate the selective generation of NO under the lattice oxygen mechanism. In addition, kinetic calculations elucidated the transition of catalysts from amorphous to crystalline state in catalysis. Finally, suggestions were made for the current characterization techniques of catalysts. This study offers a reference point for the catalyst design of AP decomposition-oriented products, which is beneficial for the transition to more environmentally-friendly products.

Catalytically ultrathin titania coating to enhance energy storage and release of aluminum hydride via atomic layer deposition

Aluminum hydride (AlH3) has attracted much attention owing to its extraordinary hydrogen storage performance, yet AlH3 is prone to hydrogen release reaction during long-term storage, leading to a decrease in energy and hindering its practical application. Herein, AlH3 particles are stabilized by catalytically ultrathin TiO2 coating via atomic layer deposition (ALD), the hydrogen content of which is controllable and reduces only 0.0026 wt% per ALD cycle of TiO2 coating. 30 cycles of TiO2 (2.4 nm) coated AlH3 exhibits a peak decomposition temperature of 203.42 ℃ and decomposition activation energy of 112.21 kJ/mol, which are 7.83 ℃ and 22.64 kJ/mol higher than those of bare AlH3. The hydrogen content loss of TiO2 coated AlH3 under hydrothermal aging conditions is much lower than that of bare AlH3 due to the passivation of defects on native Al2O3 by forming inert Al2O3 and catalytic TiO2 double-shell coating structure. TiO2 coated AlH3 exhibits enhanced combustion performance with stronger flame radiation intensity compared to bare AlH3. The density functional theory calculations indicate that the contact between AlH3 and TiO2 can weaken the strength of Al-H ion bond and promote the release of hydrogen. Our work offers a feasible method for simultaneously improving the stability and energy release of AlH3.

Performance of limestone calcined clay cement (LC3) made with CO2-mineralized concrete slurry waste

Concrete slurry waste (CSW) is an under-recycled material with great potential to be substitute ordinary Portland cement (OPC) after proper treatment. In this study, dehydrated CSW (DCSW) was used to mineralize CO2 and the carbonated product was used to prepare limestone calcined clay cement (LC3). The results showed that the CaCO3 content of carbonated DCSW (CDCSW) reached ∼57.7% after mineralization for 8.5 h. During carbonation the Portlandite peak disappeared after 1.5 h, and the Mc_AFm peak disappeared after 3.5 h. The alite and belite peaks gradually diminished, with a weak diffraction remaining at 8.5 h. Replacing limestone with CDCSW led to a decrease of 14.7% in fluidity, at a plasticizer dosage of 1.3%. The compressive strength of LC3-cdcsw mortar specimens was higher than those of LC3-limestone specimens at all ages. The effective chloride diffusion coefficient of LC3-cdcsw was also promisingly small (1.08 × 10−11 m2/s). The comprehensive properties (grey correlation degree) of LC3-cdcsw were 17.82% lower than that of OPC, but 17.73% higher than that of ordinary LC3. At 28 d, the contents of monocarboaluminate for LC3-cdcsw and LC3-limestone are 11.2% and 9.5%, respectively. The fourth thermal decomposition peak of LC3 system is higher than that of OPC, and the peak intensity of LC3-cdcsw is lower than that of LC3-limestone. Our work explores the pathway of carbon sequestration in concrete slurry waste for the preparation low-carbon and durable cementitious materials.

Degradation analysis of lithium-ion batteries under ultrahigh-rate discharge profile

Lithium-ion batteries (LIBs) demonstrate significant potential in military applications. While, in application scenarios such as electromagnetic emission, directional energy, LIBs need to be discharged under ultrahigh rates for a long time, which can lead to accelerated performance degradation. To conduct an in-depth study on the degradation behaviour of LIBs under these conditions, this study proposes a peak decomposition method for incremental capacity analysis. This method permits a nuanced quantification of distinct degradation modes within LIBs. The effects of ultrahigh-rate constant-current discharge, ultrahigh-rate pulse discharge, and standard-rate discharge on battery degradation mode are compared. Furthermore, we delve into the fundamental processes potentially underpinning the disparities observed among these degradation modes. The results show that the degradation mode of the batteries aged under ultrahigh-rate discharge profile is dominated by the loss of active material compared with that of the batteries aged under standard-rate discharge profile. Upon reaching 80% state of health, the batteries aged under ultrahigh-rate constant-current discharge and ultrahigh-rate pulse discharge retain 87.3% and 88.51% of their initial active material content, respectively. In addition, lithium plating may have occurred in the charging process of the battery aged under ultrahigh-rate pulse discharge.

Copper stearate-coated DAP-4 core–shell composites for enhanced safety and thermal decomposition performance

In this study, DAP-4@copper stearate (CS) core–shell composites were fabricated by an in situ synthesis and liquid deposition using CS as the catalyst. In addition, a comprehensive characterization was conducted on the morphology, structure, thermal decomposition, and safety performance of the acquired samples. The results revealed that DAP-4@CS composites with a complete, compact core–shell structure. During thermal analysis experiments, DAP-4@CS (5, 10, 15, and 20 wt%) resulted in a reduction in the thermal decomposition peak temperatures (Tp) by 35.22, 55.02, 68.22 and 73.76 °C respectively when compared with DAP-4, and their corresponding activation energy values decreased by 61.22, 87.3, 63.62, and 69.54 kJ/mol. Notably, the DAP-4@CS composites with 5 wt% and 10 wt% CS exhibited increased heat release by 1291.03 and 1546.8 J/g, respectively. The H50 value for DAP-4 increased from an initial value of 44.67 cm to an improved value of 64.57 cm, while its friction sensitivity increased from 30 N to 40 N during safety experiments. Moreover, we propose the principle of thermal decomposition catalysis and desensitization of CS for DAP-4. The above research results provide a new solution to the contradictions and obstacles in the application of DAP-4 as an oxidizer in fuel.

Unveiling the carbonation behavior of T-C3S and M-C3S: A comparative investigation

Numerous studies have investigated the carbonation process of tricalcium silicate (C3S). However, research on the carbonation of its different crystal forms remains relatively limited. This study explored the effects of accelerated carbonation on the performance and microstructure of T-C3S and M-C3S. The findings indicated that both T-C3S and M-C3S exhibited a rapid carbonation reaction rate during the initial 12 h, which subsequently declined gradually. The carbonation products of T-C3S and M-C3S primarily consisted of calcite, with T-C3S also containing a proportion of aragonite calcium carbonate. The decomposition peak temperature of calcium carbonate weight loss increased with prolonged carbonation time for both C3S crystal forms. Prismatic or cubic morphology calcite formed in T-C3S and M-C3S during the initial carbonation stages, leading to a denser microstructure. As the carbonation duration increased, the particle size of calcite also grew, displaying a more irregular morphology. Furthermore, needle-like or rod-like aragonite calcium carbonate was observed in T-C3S. T-C3S exhibited superior compressive strength compared to M-C3S at all stages of carbonation. Additionally, a relationship was established between compressive strength, calcium carbonate content, and CO2 uptake. This study provided evidence that the crystal structure of C3S not only influenced the rate of the carbonation reaction but also impacted the type and morphology of calcium carbonate products and the development of compressive strength.

Customized Green Energetic Tetra(Imidazole)Copper(II) Nitrate (Cu-Im) Complex/Ammonium Nitrate Co-crystal: A Novel Reactive Halogen-Free Oxidizer with Superior Stability and Decomposition Kinetics

AbstractAmmonium nitrate (AN) is the most promising affordable green oxidizer for solid propellants; however, its endothermic phase transitions and endothermic decomposition restrict its applications. This work shaded the light on multifunctional energetic complex tetra(imidazole)copper (II) nitrate (Cu-Im) with combustion enthalpy of 15.57 KJ/g as a high energy dense material, phase stabilizer, and catalyst for AN-based propellant. The Cu-Im complex was synthesized via a green simple solvent-free melt-assisting technique. As-synthesized Cu-Im complex demonstrated a highly pure crystalline structure with thermal stability up to 200 °C. Cu-Im complex was integrated into AN via an evaporative crystallization technique. The phase transitions and the thermal behavior of the developed Cu-Im complex/AN cocrystal were investigated via DSC and TGA. The Cu-Im complex stabilized the phase transition of AN up to 88.48 °C via an evolved strong hydrogen bonding system within the Cu-Im complex/AN cocrystal. Moreover, the energetic Cu-Im complex offered a significant decrease in the endothermic phase transition peaks associated with IV↔II, and II↔I by 38.81%, and 25.28% respectively. Additionally, AN strong endothermic melting was decreased by 45.32%. The Cu-Im complex converts the AN endothermic thermal decomposition peak with + 1400 J/g into an intensive exothermic peak with the release of -2241 J/g. The Cu-Im complex exhibited a superior catalytic effect via the decrease in AN decomposition temperature by 48.85 °C. Cu-Im complex offered a remarkable reduction in apparent activation energy of AN decomposition by 56.24% and 48.12% via Kissinger’s model and integral iso-conversional nonlinear Vyazovkin method (VYA) respectively. The superior catalytic performance of the Cu-Im complex was attributed to the evolution of CuO nanoparticles during its decomposition. The electron-deficient Lewis acid copper ions have a large affinity to electron lone pair of nitrogen; this effect could support the conversion of NH3 to N2 and H2. This catalytic action could boost the decomposition enthalpy of AN. Consequently, the developed Cu-Im/AN cocrystal could be considered a potential green substitute for perchlorate-based oxidizers.

Thermal recombination strategy designed R-CN as active shell to improve catalyst activity

A new recombinant CN material (R-CN) was prepared with g-C3N4 as precursor by hydrothermal method combined with thermal recombination method, which has 2D ultra-thin structure, nanoscale folds, graphite-like texture and some pores, and has richer N and O elements than g-C3N4. R-CN can reduce high temperature decomposition peak of ammonium perchlorate (AP) to 356.06 oC, and its promoting effect is obviously better than that of g-C3N4. Based on specific structural composition and physicochemical properties of R-CN, a novel R-CN@MWO composite with core-shell was designed, which was applied to catalytic decomposition of AP and pressure enlarging effect during combustion process of cyclotrimethylenetrinitramine (RDX)+nitrocellulose (NC). With the introduction of R-CN@MWO, decomposition peak temperature and activation energy of AP are reduced by 104.67oC and 59.24 kJ mol−1, and peak pressure and pressurization rate of RDX+NC constant volume combustion test are increased by 11.33 and 118.54 times, respectively. Moreover, the combustion rate of R-CN@MWO-AP/HTPB propellant is 3.23 times that of AP/HTPB propellant. To sum up, R-CN as a coating layer can significantly enhance catalytic activity of MgWO4 for thermal decomposition of energetic materials.

Characterizing Canopy Structure Variability in Amazonian Secondary Successions with Full-Waveform Airborne LiDAR

Full-waveform LiDAR (FWF) offers a promising advantage over other technologies to represent the vertical canopy structure of secondary successions in the Amazon region, as the waveform encapsulates the properties of all elements intercepting the emitted beam. In this study, we investigated modifications in the vertical structure of the Amazonian secondary successions across the vegetation gradient from early to advanced stages of vegetation regrowth. The analysis was performed over two distinct climatic regions (Drier and Wetter), designated using the Maximum Cumulative Water Deficit (MCWD). The study area was covered by 309 sample plots distributed along 25 LiDAR transects. The plots were grouped into three successional stages (early—SS1; intermediate—SS2; advanced—SS3). Mature Forest (MF) was used as a reference of comparison. A total of 14 FWF LiDAR metrics from four categories of analysis (Height, Peaks, Understory and Gaussian Decomposition) were extracted using the Waveform LiDAR for Forestry eXtraction (WoLFeX) software (v1.1.1). In addition to examining the variation in these metrics across different successional stages, we calculated their Relative Recovery (RR) with vegetation regrowth, and evaluated their ability to discriminate successional stages using Random Forest (RF). The results showed significant differences in FWF metrics across the successional stages, and within and between sample plots and regions. The Drier region generally exhibited more pronounced differences between successional stages and lower FWF metric values compared to the Wetter region, mainly in the category of height, peaks, and Gaussian decomposition. Furthermore, the Drier region displayed a lower relative recovery of metrics in the early years of succession, compared to the areas of MF, eventually reaching rates akin to those of the Wetter region as succession progressed. Canopy height metrics such as Waveform distance (WD), and Gaussian Decomposition metrics such as Bottom of canopy (BC), Bottom of canopy distance (BCD) and Canopy distance (CD), related to the height of the lower forest stratum, were the most important attributes in discriminating successional stages in both analyzed regions. However, the Drier region exhibited superior discrimination between successional stages, achieving a weighted F1-score of 0.80 compared to 0.73 in the Wetter region. When comparing the metrics from SS in different stages to MF, our findings underscore that secondary forests achieve substantial relative recovery of FWF metrics within the initial 10 years after land abandonment. Regions with potentially slower relative recovery (e.g., Drier regions) may require longer-term planning to ensure success in providing full potential ecosystem services in the Amazon.

A high density and low sensitivity carrier explosive promising to replace TNT: 3-Bromo-5-fluoro-2,4,6-trinitroanisole

To address the issues of high saturated vapor pressure, high toxicity, and high viscosity of TNT, this article used a chemical method to synthesize a new carrier explosive BFTNAN. The prepared samples were characterized using scanning electron microscope(SEM), energy spectrum(EDS), x-ray diffraction(XRD), infrared spectrum(IR), x-ray photoelectron spectroscopy(XPS), nuclear magnetic resonance, and elemental analysis techniques. The enthalpy of formation of BFTNAN was measured using a specialized calorimeter that is specially used in testing of explosives and powders. The thermal decomposition performance of BFTNAN was tested by DSC technology. Meanwhile, the mechanical sensitivity, thermal sensitivity, and detonation performance of BFTNAN based melt-cast explosive was also tested. The results of characterizations showed that the prepared sample was indeed BFTNAN. The enthalpy of formation of BFTNAN was determined as ΔHf,BFTNAN = −72.6 kJ·mol−1. At a heating rate of 20 °C·min−1, the thermal decomposition peak of BFTNAN is at TP = 250.6 °C, and the activation energy is EK = 80 kJ·mol−1, which is closed to the Tp and EK values of TNT. This indicates that BFTNAN is a relatively easy to decompose explosive, but the decomposition rate is not fast. The critical temperature for thermal explosion of BFTNAN reached Tb = 216 °C, which is also closed to the Tb value of TNT. The impact and friction sensitivity of BFTNAN were lower than those of TNT, which was closed to those of DNAN. The thermal sensitivity of BFTNAN is lower than TNT. The detonation velocity and heat of explosion of BFTNAN based melt-cast explosive were distinctly higher than those of TNT based explosive. Especially, BFTNAN based melt-cast explosive were of the advantages in chemical energy storage, work capacity, brisance, and ability of acceleration metals.

Preparation of metal–organic framework-199 (Cu) and their effects on catalytic decomposition of hexahydro-1,3,5-trinitro-s-triazine

In this study, a series of metal–organic framework-199 (MOF-199) products were prepared with copper (Cu) as the metal center and trimesic acid as the organic ligand. The morphological changes of MOF-199 under different preparation conditions and its application in the catalytic thermal decomposition of hexahydro-1,3,5-trinitro-s-triazine (RDX) were studied. The morphological changes of MOF-199 were compared by scanning electron microscopy (SEM), the crystal structures of MOF-199 were analyzed by X-ray diffraction and the effects of MOF-199 with different morphological characteristics on the thermal decomposition behavior of RDX were studied by differential scanning calorimetry. The results showed that MOF-199 with different morphologies could effectively adjust the thermal decomposition process of RDX and reduce the decomposition peak temperature of RDX, and the catalytic effect of MOF-199 was different due to different crystal surfaces exposed. Among them, (110) was a highly active crystal plane with a high catalytic activity. In addition to the crystal plane structure, the defects on the surface of MOF-199 would also affect its catalytic performance. This study provides some theoretical support for the catalytic mechanism of MOFs in the thermal decomposition of nitro compounds.

Batch synthesis of 2,4,6‐trinitro‐3‐bromoanisole and its thermolysis and combustion performance

AbstractA new carrier explosive TNBA was batch synthesized by a chemical method. The prepared samples were characterized using SEM, EDS, XRD, IR, XPS, nuclear magnetic resonance, and elemental analysis techniques. The enthalpy of formation of TNBA was measured using a specialized calorimeter that is specially used in testing of explosives and powders. The thermal decomposition performance of TNBA was tested by DSC technology. Meanwhile, the combustion performance of TNBA was also tested. The results of characterizations showed that the prepared sample was indeed TNBA. The enthalpy of formation of TNBA was determined as ΔHf,TNBA=+48.5 kJ/mol. At a heating rate of 20 °C/min, the thermal decomposition peak of TNBA is at TP=285.3 °C, and the activation energy is EK=91 kJ/mol, which is higher than the Tp and EK values of TNT. This indicates that TNBA is a relatively easy to decompose explosive, but the decomposition rate is not fast. The critical temperature for thermal explosion of TNBA reached Tb=247 °C, which is higher than the Tb value of TNT, slightly lower than the Tb value of DNAN, and significantly higher than the Tb value of DNTF, TNAZ, and MTNP. The combustion performance test results showed that the TNBA sample has the highest combustion pressure and the highest pressurization rate; and the TNBA sample has the highest combustion temperature; however, due to the high oxygen balance, the combustion heat of TNBA samples in excess pure oxygen is not the highest.

Effect of Cubic Crystal Morphology on Thermal Characteristics and Mechanical Sensitivity of PYX

To investigate the influence of the cubic crystal morphology on the thermal properties and sensitivity of 2,6-bis(picrylamino)-3,5-dinitropyridine (PYX), cubic PYX (CPYX) crystals were prepared using the antisolvent method. Scanning electron microscopy (SEM), laser particle size analysis, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the morphology, particle size and structure of the prepared products. The thermal behavior, thermal decomposition kinetics, thermal safety parameters and thermal decomposition mechanism of CPYX were investigated by differential scanning calorimetry–thermogravimetry–mass spectrometry–Fourier transform infrared spectrometry (DSC-TG-MS-FT-IR) and in situ FT-IR experiments. Meanwhile, the mechanical sensitivity of CPYX was determined by means of the explosion probability method. The results showed that the product had a smooth cubic morphology and small crystal aspect ratio with an average particle size (d50) of 10.65 μm, but it had no distinct differences from the crystal structure of raw PYX (RPYX). The thermal decomposition peak temperature, the self-accelerating decomposition temperature and the critical temperature of the thermal explosion of CPYX increased by 7.2 °C, 6.1 °C and 10.4 °C, respectively, compared to RPYX. Similarly, the apparent activation energy increased by 15%. Besides these, the impact sensitivity and friction sensitivity of CPYX decreased by 36% and 20%, respectively, compared to RPYX. The decomposition process of CPYX contains two stages. The first stage involves the breakage of N-H bonds and -NO2 groups with the release of CO2, N2O, NO, HCN and H2O, followed by the thermal decomposition of the resulting intermediate and the release of CO2, N2O and HCN in the second stage.

Efficient Synthesis, Characterization, and DFT Calculation of 4,4’-Azo-1,2,4-triazole

ABSTRACT 4,4’-Azo-1,2,4-triazole (atrz) is a new high nitrogen energetic material with high energy density, high gas yield and wide application prospects, but the low synthesis temperature and long time are the main reasons limiting its application. To achieve efficient synthesis of atrz, the double drop synthesis method was designed to solve the problem of unstable concentration of oxidant (HClO) due to batch feeding. The reaction temperature, reaction time, and molar ratio of reactants of n(4-amino-1,2,4-triazole):n(ClO−) were studied and optimized using the single factor variable method; Characterization and analysis of atrz using theoretical calculations with elemental analysis, infrared spectroscopy, crystal morphology, and nuclear magnetic resonance; The thermal properties and stability of atrz were tested and analyzed using TG-DTA. The results showed that the reaction time of the double drop synthesis method was shortened from 5 hours to 1.5 hours under the conditions of similar yield, and the efficiency was increased by 2.3 times. The optimized process was a reaction temperature of 5°C-10°C, reaction time of 1.5 hours, n(4-amino-1,2,4-triazole):n(ClO−) of 1:2, and the yield reached 73%. The product was white, needle-like crystals, which were determined to be atrz by means of characterization and theoretical calculations. Atrz’s decomposition peak temperature is 309.0°C, and when the temperature is below 271.7°C, atrz is thermally stable. The activation energies of atrz calculated by Kissinger and Flynn-Wall-Ozawa methods were 195.0 kJ·mol−1 and 194.6 kJ·mol−1.

Elucidating the Reductive Decomposition Mechanism in Sulfide Solid Electrolyte Li4SnS4.

The sulfide solid electrolyte Li4SnS4 has garnered considerable interest due to its exceptional moisture durability, which is attributed to its stable hydrated state. However, a major limitation of certain sulfide solid electrolytes, including Li4SnS4, is their low reduction durability, which limits their application in the negative electrodes of all-solid-state batteries and impedes qualitative material development assessments. In this study, we introduced a quantitative and straightforward method for evaluating the reductive decomposition of Li4SnS4 to better understand its degradation mechanism. The configuration of the electrochemical evaluation cell was modified from SUS|Li4SnS4|Li to SUS|Li4SnS4|Li3PS4|Li, allowing for stabilization of the reference potential of the counter electrode. The reductive decomposition potential of Li4SnS4 was quantitatively assessed by using cyclic voltammetry in a two-layer electrochemical evaluation cell. We observed a minor irreversible reduction current below +1.2 V and a pronounced decomposition peak at +1.0 V. Notably, reductive decomposition continued below 0 V, which is typically the onset point for Li electrodeposition. Postreduction, the solid electrolyte was comprehensively analyzed through optical microscopy, X-ray diffraction, and X-ray absorption spectroscopy. These analyzes revealed the following: (i) The SnS44- unit in Li4SnS4 initially decomposes into Li2S and β-Sn with the dissociation of the Sn-S bond; (ii) the resulting β-Sn forms LixSn alloys such as Li0.4Sn; and (iii) the ongoing reductive decomposition reaction is facilitated by the electronic conductivity of these LixSn alloys. These findings offer crucial methodological and mechanistic insights into the development of higher-performance solid electrolyte materials.