Thermal Decomposition Properties Research Articles

Spherical core-shell CL-20@LLM-105 composites with excellent mechanical sensibility obtained by Pickering emulsion

The effect of crystallization conditions on the morphology, particle size and dispersibility of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) was investigated by solvent-nonsolvent method, and nano-LLM-105 was successfully prepared and used as a surfactant after modification with stearic acid. A spherical core-shell composites of CL-20@LLM-105 was prepared by Pickering emulsion method. The morphology, crystal structure, and thermal decomposition properties were characterized by scanning electron microscopy (SEM), powder X-ray diffractometry (XRD), differential scanning calorimetry (DSC), fourier transform infrared (FT-IR) tested for impact and friction sensibility. The results showed that the prepared composites had a particle size of 50–100 μm, a spherical core-shell structure, and nano-LLM-105 was encapsulated on its surface. The peak thermal decomposition temperature of the composites was 252.7 ℃, which was 9.4 ℃ higher than that of the raw material CL-20. Compared with the CL-20/LLM-105 mixture with the same ratio, the characteristic drop height (H50) of the CL-20@LLM-spherical compoe-shell site was increased by 13 cm, and the explosion probability (P) was reduced by 43%. The spherical core-shell composites prepared by this method is characterized by high energy and excellent mechanical sensibility, which is expected to provide new ideas for the design of explosive formulations containing CL-20 and nanoenergy-containing materials in the direction of high safety and high energy.

Synergetic impact of binary/ternary zeolitic composites on cellulose acetate membranes for potential CO2 removal and antibacterial attributes

The aim of this research is to synthesize multifunctional mixed matrix cellulose acetate (CA) membranes that can provide better CO2/N2 selectivity and will simultaneously fight against bacteria, to immaculate the indoor environment. For that purpose, two different fillers labelled as binary ZnO@Zeolite (1:10, ZZ) and ternary ZnO–CuO@Zeolite (0.8:0.2:10, ZZC) composites have been synthesized via co-precipitation method to entrench into CA matrix with 8 wt% each. The solution mixing technique assisted by thermal evaporation process (TEAP) has been adopted to formulate the desired membranes. Surface morphology, crystalline structure, thermal decomposition, and mechanical properties of novel composites ZZ and ZZC, along with their respective corresponding membranes CA/ZZ-8 and CA/ZZC-8, have been analyzed using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and universal testing machine (UTM). The inclusion of tri-zeolitic composite (ZZC) favors the formation of denser CA membranes, with a smaller crystallite size (10.8 nm), higher thermal stability (%), and a notable increase in mechanical strength (MPa) in contrast to virgin CA as well as bi-zeolitic composite (ZZ) loaded membranes. The selectivity for CO2/N2 separation of tri-zeolitic composite loaded membranes (CA/ZZC-8) is almost six folds higher compared to the pristine CA membrane, whereas it is five folds for bi-zeolitic composite impregnated membrane (CA/ZZ-8). To eradicate bacterial fouling, bi/tri-zeolitic composite loaded membranes are tested against E. coli bacteria by broth culture method and the results validate their antibiotic nature. Synthesized novel CA membranes with hybrid composites provide convenient access towards the development of multipurpose membranes.

Preparation and Reactivity of Core-Shell Al@CL-20 Composites Embedded with Graphene-Based Complexes as Catalysts.

Incomplete combustion of Al in solid propellants can be effectively resolved by coating of an oxidizer at the microscale. In this paper, Al@CL-20 composites with polydopamine as the interfacial layer were prepared using this strategy. The structure, heat of reaction, thermal decomposition properties, and combustion performances of these composites under the effects of graphene oxide (GO) and graphene-based carbohydrazide complexes (GO-CHZ-M, M = Co2+, Ni2+) have been comprehensively investigated. The experimental results show that the heat of reaction of Al@CL-20 is 6482 J g-1, which is 561 J g-1 higher than that of the corresponding mechanical mixture. The presence of GO-CHZ-Co can further increase the heat of reaction of Al@CL-20 to 6729 J g-1 with a decreased activation energy by about 54.8%. Under the synergistic effect of interfacial control and GO-CHZ-M, the ignition delay time of Al@CL-20-Co decreases from 5.1 to 4.2 ms. Besides, the D50 of the combustion condensed products (CCPs) decreased from 5.62 to 4.33 μm, indicating the combustion efficiency of Al is greatly improved.

Thermal decomposition characteristics of BHT and its peroxide (BHTOOH).

2,6-Di-tert-butyl-4-methylphenol (BHT) is an excellent antioxidant that is easily oxidized to 2,6-di-tert-butyl-4-hydroperoxyl-4-methyl-2,5-cyclohexadienone (BHTOOH). For the safety of BHT production and usage, it is meaningful to study the thermal stability and decomposition properties of BHT and BHTOOH. In this paper, the thermal decomposition properties of BHT and BHTOOH were compared by the mini closed pressure vessel test (MCPVT) and differential scanning calorimetry (DSC). Their kinetics of thermal decomposition were studied using thermogravimetric analysis (TGA). The thermal decomposition products of BHT and BHTOOH were analyzed by gas chromatography-mass spectrometry (GC-MS). The results show that there was no significant change in temperature pressure when BHT was warmed up under a nitrogen atmosphere, indicating that BHT was stable within 400K. The thermal decomposition reaction of BHTOOH was rapid with an initial reaction temperature of 375.2K. The initial exothermic temperature (Ti) and heat release (QDSC) of DSC were 384.9K and 865.0Jg-1, respectively. The apparent activation energies (Ea) for the thermal decomposition reactions of BHT and BHTOOH calculated by the Kissinger method were 151.8kJmol-1 and 66.07kJmol-1, respectively. The main decomposition products of BHT were isobutene and 2-tert-butyl-4-methylphenol. The thermal decomposition products of BHTOOH included BHT, 2,6-di-tert-butyl-4-ethylphenol, 3,5-di-tert-butyl-4-hydroxybenzaldehyde, 4,4'-(1,2-ethanediyl) bis [2,6-bis (1,1-dimethylethyl) phenol, etc. Based on the thermal decomposition behavior and products, the reaction pathway has been described. These results indicate that BHT is a potential thermal hazard during production, storage and application. For the safety of the chemical industry, the oxidation of BHT should be avoided.

Effect of flame retardants and 1% stabiliser on thermal decomposition and physics properties of thermoplastic polymer due to TGA and DTA tests

This work introduces seven various polymer samples blended in a twin-screw extruder with flame retardants (FR), and an additive, which is a 1% Stabiliser, to investigate thermoplastic polymer melting, thermal decomposition, and melting moderates. The reduction method is used to analyze its melting points, physics and chemical properties, and thermal decomposition. Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) tests are known as thermal analysis tests. It was established that halogenated flame retardants have little effect on reducing the rate of gas escape from polymer melt which affects the viscosity, as it was found. Thus, the APP and FR245 in Polymer help in some polymer leftovers. All samples were treated with flame retardants and no clay, melted completely, at the end of the test some samples did change. All these results investigated by (the XRD) test either, Scanning Electron Microscopic (SEM) or Digital images have been used also applied Limiting oxygen index (LOI) test, in the previous work for the same samples of polymers to verify the results and record a more precise outcome to draw the relationship between melting and dripping behavior via the following studies due to the furnace test which is modulated and calibrated. As a result, the addition of clay together with conventional flame retardants enhances the overall thermal stability forming the polymer. The compatibles help in improving the dispersion of the clay in polymer and reduce the rate of gas escape from polymer melt affecting the viscosity.

Construction of microstructurally controllable B/BaCrO4 particles based on droplet microfluidic technology for enhanced usability and delay precision

Tuning the microstructure of composite energetic materials is an effective way to improve charging, safety, and combustion performance. In this paper, boron (B)/barium chromate (BaCrO4) composite particles with controllable microstructure were prepared using droplet microfluidic technology (DMT). Based on the theory of droplet template self-assembly, composite particles with controllable morphology, size, and composition were prepared, revealing the regulation mechanism of the particle microstructure. The composite particles prepared using DMT exhibit a uniform distribution of characteristic elements, high circularity, smooth surface, enhanced bulk density, and excellent flow properties. The thermal decomposition characteristics, safety, and combustion properties of the samples were investigated by thermal weight loss, mechanical sensitivity, and combustion tests. Thermal weight loss and mechanical sensitivity tests showed that the samples had stable thermal decomposition properties and significantly increased mechanical stability compared to the control. The combustion test results showed that the DMT-prepared samples had a short ignition response time and significantly improved delay precision. This paper presents a straightforward method for preparing B/BaCrO4 particles with high delay accuracy, which can serve as a reference for preparing other composites.

RTV silicone rubbers cured by polyhedral oligomeric silsesquioxane and ladder-like polysilsesquioxane: Thermostability, long-term thermal properties, and pyrolysis mechanism

At present, silicone rubber has been widely used in the fields of aerospace and electronic materials, yet its long-term thermal performance still remains a challenge. In this investigation, polyhedral oligomeric silsesquioxane and ladder-like polysilsesquioxanes with multiple silicon-methoxy groups (MSPOSS, MSLPSQ) were synthesized successfully and used as cross-linkers to cure room temperature vulcanized silicone rubber (POSS-SR, LPSQ-SR). The results demonstrate that both MSPOSS and MSLPSQ can effectively improve thermostability, mechanical properties, and long-term thermal properties of RTV silicone rubber. The silicone rubber exhibits a remarkable preservation of strength and flexibility after long-time heat treatment at 400 °C. The silicone rubber demonstrates an impressive retention rate of 84.52% for tensile strength and 69.16% for elongation at break. An analysis of the pyrolysis process of the silicone rubber reveals that the 'back-biting' of polysiloxane chains were inhibited effectively by both MSPOSS and MSLPSQ. As a result of this inhibition, the silicone rubber's terminal chains are delayed from decomposing, resulting in retardation of initial thermal decomposition and significant improvement long-term thermal properties. This work may provide a new prospect for room temperature vulcanized silicone rubber for aerospace applications in extreme environments.

Thermal hazard evaluation and risk assessment of 1-allyl-3-methylimidazole nitrate ionic liquid

Imidazole ionic liquids (ILs) have broad application prospects in batteries and other fields. Researching the thermal decomposition features of ILs holds paramount importance for the application in battery electrolyte. 1-allyl-3-methylimidazole nitrate ionic liquid (IL) as a new functional IL, and its related thermal decomposition properties are unknown. In this paper, the thermal decomposition peculiarities of 1-allyl-3-methylimidazole nitrate IL were systematically analyzed by thermogravimetric analyzer, differential scanning calorimetry, and accelerating rate calorimeter techniques, and the relevant thermodynamic parameters and thermal decomposition models were derived. In addition, 1-allyl-3-methylimidazole nitrate IL possesses strong thermal runaway characteristics and the risk of thermal runaway is also evaluated. The main gaseous products formed by the pyrolysis of 1-allyl-3-methylimidazole nitrate IL was detected and analyzed by thermogravimetry-Fourier transform infrared spectroscopy and thermogravimetric-photoionization mass spectrometry techniques. The results showed that flammable gas, toxic gas, and asphyxiating gas are formed during the pyrolysis of 1-allyl-3-methylimidazole nitrate IL. This study lays a theoretical foundation for the safe application and the formulation of corresponding safety protection measures of 1-allyl-3-methylimidazole nitrate IL.

Investigation of the structure-property relation for graphene oxide based acrylonitrile butadiene styrene nanocomposites

The improvement of the structure-property relation in nanocomposites between different polymer matrices and the embedded nano-additives has become a strategic blueprint for many academic counterparts around the globe. In this work, different loadings of graphene oxide (GO) varied from 1.0 to 3.0 wt. % were mixed with acrylonitrile butadiene styrene (ABS) using solution casting approach. The resulted nanocomposites underwent to spectral, structural, morphological, mechanical, thermal and thermomechanical tests. Different kinds of instruments associated with each test were employed to draw a professional conclusion about the potential improvement in structure-property relation. The targeted improvement was achieved as spectral, structural and morphological investigations confirmed the interaction, structural variation, and good dispersion of GO in ABS; respectively. Furthermore, as GO loadings went higher, the mechanical, thermal, and thermomechanical performances for the nanocomposites were improved compared to the neat polymer. Young’s modulus, tensile strength, thermal decomposition, and visco-elastic properties showed an enhancement compared to the neat polymer. The mechanical and thermomechanical performances for the nanocomposites recorded significant promotions.

Thermal decomposition mechanism and characterization of phosphogypsum in suspension under multifactor coupling effect

Phosphogypsum (PG) is solid waste generated by the phosphate fertilizer industry. However, by high-temperature thermal treatment, it can be effectively decomposed into byproducts like SO2 and CaO, which are valuable raw materials for the production of sulfuric acid and construction materials, respectively. In this study, we investigated the thermal decomposition properties of suspended PG, as well as the factors governing the PG decomposition procedure. The results show that the PG decomposition rate was influenced by several parameters, with temperature being the most significant, followed by time, atmosphere, and charcoal powder dosing. Similarly, the desulfurization rate was primarily influenced by time, followed by temperature, atmosphere, and charcoal powder dosing. The PG exhibited maximum decomposition and desulfurization rates of 97.73% and 97.2%, respectively, at a calcination temperature of 1180 °C, a calcination period of 15 min, a carbon powder dosage of 4%, and a CO concentration of 6%. Kinetic studies revealed that the activation energy of the PG decomposition reaction decreased from 303.45 to 254.28 kJ/mol as the CO concentration increased from 4% to 6% upon addition of charcoal powder as a reducing agent. Furthermore, higher CO concentrations had a more pronounced effect on lowering the activation energy of PG pyrolysis. When the contents of SiO2 and Al2O3 impurities in the PG content were higher, they reacted with CaO in the decomposition products to produce silicate and aluminate minerals, respectively, decreasing both the CaO content in the product and the PG decomposition rate.

Facile Grinding Method for Preparing Nano-Cu-Cr-Fe Composite Metal Oxides with Enhanced Catalytic Activity for Thermal Decomposition of Ammonium Perchlorate

ABSTRACT Ammonium perchlorate (AP) is a commonly used oxidant for solid propellants, and improving the thermal decomposition performance of AP has been the focus of research, as its thermal decomposition performance directly affects the performance of the propellant. Among a variety of catalysts, nanocomposite metal oxides have demonstrated a significant role in facilitating the thermal decomposition of AP. In this study, Cu-Cr-Fe ternary metal oxides with different molar ratios (5:2:8, 5:4:6, 5:6:4, 5:8:2) were prepared by a facile mechanical grinding method to investigate their catalytic effect on the thermal decomposition properties of AP. The structure and morphology of Cu-Cr-Fe ternary metal oxides were investigated using X-ray diffractometer (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the catalytic effect of different ternary catalysts on the thermal decomposition performance of AP was also investigated using thermal weight (TG) and differential scanning calorimetry (DSC) techniques. The results show that Cu-Cr-Fe ternary nanocomposite metal oxides with a molar ratio of 5:2:8 prepared by mechanical grinding exhibit excellent catalytic effect on the thermal decomposition of AP, as well as nanometallic oxides (Cu-Cr-Fe = 5:2:8) prepared using the co-precipitation and physical mixing methods. Furthermore, the ternary Cu-Cr-Fe (molar ratio of 5:2:8) composite metal oxide prepared by mechanical grinding resulted in a significant decrease in the thermal decomposition temperature of AP, which decreased from 441.3°C to 352.5°C, the heat of decomposition increased from 941 J/g to 1680 J/g, and the Gibbs free energy of AP decreased from 199.8 kJ/mol to 173.2 kJ/mol. This demonstrates the good synergistic catalytic effect between CuO, Cr2O3 and Fe2O3 nanoparticles, which is expected to facilitate the application of ternary nanocomposite metal oxides in the field of solid propellants.

Thermal decomposition and combustion performance of the organic-inorganic hybrid crystal structure oxidant DAN-2

In this paper, we investigated the potential use of a new organic-inorganic hybrid crystal structure based on KNO3 in ignition compositions. H2dabco[K(NO3)3] (DAN-2) with organic-inorganic hybrid crystal structure is synthesized through intermolecular assembly technology. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were used to detect the crystal morphology, structure and molecular structure of DAN-2, which has a regular cubic structure. Experimental data were obtained using thermogravimetric/differential scanning calorimetry (TG-DSC), closed bomb test and high-speed photography, which were then used to study and analyze the thermal decomposition properties and combustion properties of DAN-2. The initial thermal decomposition temperature of DAN-2 was low (194 °C) and the activation energy of the thermal decomposition was 154 kJ/mol. Possible thermal decomposition mechanisms are further discussed and proposed. This research pushed forward the application of organic-inorganic hybrid crystal structure oxidant DAN-2 in ignition system.

Construction of cobalt–nickel bimetallic coordination polymers and their catalytic thermal decomposition of ammonium perchlorate

The addition of a catalyst to ammonium perchlorate (AP) can effectively improve its thermal decomposition properties. The heterobimetallic complex Ni-Co-pzdc (2,3-pyrazinedicarboxylic acid) was synthesized via in situ substitution, and the N-doped Ni-Co-pzdc derivative was prepared by using it as a sacrificial template. A series of characterization tools were used to investigate the morphological and structural features of the resulting materials, and the thermal decomposition behaviors of the two products were investigated by homogeneous mixing with AP, respectively, and the activation energies were calculated by using Kissinger, Kissinger-Akahira-Sunose (KAS), and Flynn-Wall-Ozawa (FWO), and the results showed that both substances possessed excellent catalytic activities.

Porous nanosheets of TKX-50 by ice-templating strategy with excellent thermal decomposition and combustion properties

ABSTRACT Nanostructured energetic materials have attracted considerable research interests during the past decades because of their improved performances in thermal decomposition and combustion. In this work, a porous nanosheet structure of dihydroxylammonium 5, 5′-bistetrazole-1, 1′-diolate (TKX-50) has been fabricated by a facile ice templating strategy, which is based on the self-assembly of TKX-50 during rapid recrystallization. Thermal decomposition properties were determined by differential scanning calorimetry/thermogravimetry (DSC/TG) and TG-FTIR analyses. The laser-ignited and constant-volume combustions and mechanical sensitivity were conducted. As-prepared TKX-50 mainly presents porous nanosheets (NS-TKX-50) assembled by the secondary nanoparticles. NS-TKX-50 is typical of mesoporous materials with high specific surface area and pore volume. Compared with raw material, NS-TKX-50 exhibits lower thermal decomposition peak temperature and higher active energy. In thermal decomposition process, a great deal of gaseous products have been generated in a very narrow temperature range. These thermal decomposition features suggest a quick energy-release rate and high energy output. Contrary to incomplete combustion of raw material, NS-TKX-50 shows high-efficiency and self-sustaining laser-ignited combustion feature with a drastically decreased ignition threshold. And its pressurization rate and peak pressure are remarkably increased. Sensitivity results confirmed the visibly reduced impact and friction sensitivity of NS-TKX-50.

(Invited) Green Ammonia-Mediated CO2 Capture and Direct Electrochemical Reduction to Formate

Direct electrochemical conversion of CO2 capture solutions (instead of gaseous CO2) into valuable chemicals can circumvent the energy-intensive CO2 regeneration and pressurization steps. While commonly used CO2 capture agents include alkali and amine solutions, ammonia has been rarely investigated. In another aspect, mismanagement of reactive nitrogen (Nr) in waste has emerged as a major problem in water pollution to our ecosystems, causing severe eutrophication and health concerns. Sustainably recovering Nr [such as nitrate (NO3 −)-N] and converting it into green ammonia (NH3) could mitigate the environmental impacts of Nr and reduce the NH3 demand from the carbon-intensive Haber-Bosch process, as well as a possible CO2 capture agent due to its alkaline nature.In this talk, we will present our rencet research on integration of electrodialysis and electrocatalysis for ammonia synthesis from dilute waste Nr sources, and green ammonia-mediated CO2 capture (to ammonium bicarbonate, NH4HCO3) and subsequent reduction to ammonium formate (NH4HCO2) as a new approach to CO2 capture and utilization (CCU). We have demonstrated a record-high NO3 −-to-NH3 performance in a scalable, versatile, and cost-effective membrane-free alkaline electrolyzer (MFAEL): an unprecedented NH3 partial current density of 4.22 ± 0.25 A cm−2 with a faradaic efficiency of 84.5 ± 4.9%. We also discovered that an ammonium bicarbonate (NH4HCO3)-fed electrolyzer with an anion exchange membrane (AEM) outperforms the state-of-the-art KHCO3 electrolyzer with a bipolar membrane (BPM) owing to its favorable thermal decomposition property, which allows for a 3-fold increase in the in situ CO2 concentration, a maximum 23% increase in formate faradaic efficiency, and a 35% reduction in cell voltage by substituting BPM with the AEM. Our integrated process by combining NH4HCO3 electrolysis with CO2 capturing by on-site generated green ammonia from the electro-reduction of nitrate in MFAEL has shown a remarkable 99.8% utilization of CO2 capturing agent. Such a multi-purpose process may offer a sustainable route for the simultaneous removal of Nr wastes and streamlined CO2 capturing and upgrading to valuable chemicals.

Effect of Different Silane Coupling Agents on Properties of Waste Corrugated Paper Fiber/Polylactic Acid Composites.

The surface of plant fibers was modified by silane coupling agents to prepare plant fiber/polylactic acid (PLA) composites, which can improve the dispersion, adhesion, and compatibility between the plant fibers and the PLA matrix. In this work, three silane coupling agents (KH550, KH560, and KH570) with different molecular structures were used to modify the surface of waste corrugated paper fibers (WFs), and dichloromethane was used as the solvent to prepare the WF/PLA composites. The effects of different silane coupling agents on the microstructure, mechanical properties, thermal decomposition, and crystallization properties of the composites were studied. The mechanical properties of the composites treated with 4 wt% KH560 were the best. Silane coupling agents can slightly improve the melting temperature of the composites, and WFs can promote the crystallization of PLA. The modification of WFs by silane coupling agents can increase the decomposition temperature of the WF/PLA composites. The content and type of silane coupling agent directly affected the mechanical properties of the WF/PLA composites. The interfacial compatibility between the WFs and PLA can be improved by using a silane coupling agent, which can further enhance the mechanical properties of WF/PLA composites. This provides a research basis for the further improvement of the performance of plant fiber/PLA composites.

Inhibition effect of NH4H2PO4 on explosion flame propagation of aluminum alloy dust cloud

To investigate the inhibitory effect of NH4H2PO4 on the flame propagation of aluminum alloy dust clouds, experiments were conducted in cylindrical vertical ducts. High-speed cameras were employed to capture the explosion flames of aluminum alloy dust clouds under the coupled effect of NH4H2PO4 with different concentrations and particle sizes. The flame propagation behavior of NH4H2PO4/aluminum alloy dust was analyzed, and mathematical models were developed to describe the maximum distance and maximum velocity of NH4H2PO4 inhibition on the flame propagation of aluminum alloy dust clouds. Additionally, the inhibition characteristics of NH4H2PO4 on aluminum alloy dust explosions were studied in a 20 L spherical explosion container, and the thermal decomposition properties of NH4H2PO4 and aluminum alloy particles were investigated using a simultaneous thermal analyzer. Furthermore, the inhibition process of NH4H2PO4 on aluminum alloy dust was explored. The results demonstrate that the concentration of NH4H2PO4 has a greater impact on the inhibition effect on aluminum alloy dust, while the particle size has a smaller influence. Generally, as the concentration of NH4H2PO4 increases, the flame propagation distance and flame development rate decrease, leading to an enhanced inhibitory effect. The addition of NH4H2PO4 slows down the peak pressure of aluminum alloy dust explosions, resulting in a longer duration and smaller peak values of the “double-peak” pressure structure. When the particle size of NH4H2PO4 decreases and the concentration increases, the possibility of the “double-peak” structure decreases, forming a single-peak structure with lower peak values and pressure rise rates. The decomposition temperature of NH4H2PO4 precedes the combustion temperature of aluminum alloy particles. NH4H2PO4 absorbs thermal energy from the reaction system, exerting an inhibitory effect on aluminum alloy dust. The research findings provide valuable references for optimizing explosion suppression parameters and improving powder explosion suppression techniques.

Morphological, physical, chemical, and thermal decomposition properties of air-heat-treated balsa fruit fibers at different temperatures

Morphological, physical, chemical, and thermal decomposition properties of air-heat-treated balsa fruit fibers at different temperatures

Application of TNBA-based low eutectic mixture in melt-cast explosives

ABSTRACT In this work, two TNBA-based low eutectic mixtures, TNBA/TNAZ (TZ) and TNBA/DNTF (TD), as well as eight TNBA-based melt-cast explosives, TNBA/TNAZ/RDX (TZR), TNBA/TNAZ/HMX (TZH), TNBA/TNAZ/TKX-50 (TZT), TNBA/TNAZ/CL-20 (TZC), TNBA/DNTF/RDX (TDR), TNBA/DNTF/HMX (TDH), TNBA/DNTF/TKX-50 (TDT) and TNBA/DNTF/CL-20 (TDC), were developed as structural models. A molecular dynamics approach was used to model the cohesive energy density, binding energy, and mechanical properties of these explosives. Moreover the thermal decomposition properties and mechanical sensitivity were characterized via DSC and mechanical sensitivity tests. Finally, the EXPLO-5 software predicted the detonation properties and detonation products of the aforementioned 10 mixed explosive systems. The results showed that the four mixed explosives of TDT, TDH, TZC, and TDR had excellent performance in cohesive energy density, binding energy, and material rigidity, respectively. The temperature difference was comparatively significant between the melting temperature and decomposition temperature of the eight types of mixed explosives, up to 170.60 K, with TDH and TZH having the highest thermal decomposition temperature at approximately 520 K. The six kinds of mixed explosives of TZR, TZH, TZT, TDR, TDH, and TDT had moderate mechanical sensitivities. . The five types of mixed explosives, TZT, TZC, TDH, TDT, and TDC, had the greatest detonation velocity.

Asymmetrical Methylene-Bridge Linked Fully Iodinated Azoles as Energetic Biocidal Materials with Improved Thermal Stability

The instability and volatility of iodine is high, however, effective iodine biocidal species can be readily stored in iodinated azoles and then be released upon decomposition or detonation. Iodine azoles with high iodine content and high thermal stability are highly desired. In this work, the strategy of methylene bridging with asymmetric structures of 3,4,5-triiodo-1-H-pyrazole (TIP), 2,4,5-triiodo-1H-imidazol (TIM), and tetraiodo-1H-pyrrole (TIPL) are proposed. Two highly stable fully iodinated methylene-bridged azole compounds 3,4,5-triiodo-1-((2,4,5-triiodo-1H-imidazol-1-yl)methyl)-1H-pyrazole (3) and 3,4,5-triiodo-1-((tetraiodo-1H-pyrrol-1-yl)methyl)-1H-pyrazole (4) were obtained with high iodine content and excellent thermal stability (iodine content: 84.27% for compound 3 and 86.48% for compound 4; Td: 3: 285 °C, 4: 260 °C). Furthermore, their composites with high-energy oxidant ammonium perchlorate (AP) were designed. The combustion behavior and thermal decomposition properties of the formulations were tested and evaluated. This work may open a new avenue to develop advanced energetic biocidal materials with well-balanced energetic and biocidal properties and versatile functionality.