Thermal decomposition studies on double-base propellant compositions

Thermal reactivity studies were carried out in the temperature range 100–160 on two double-base propellant compositions which differ significantly in chemical composition, calorimetric value and ballistic characteristics. The course of decomposition was followed by two methods: (i) determining the rate of NO evolved with the Bergman and Junk method; (ii) estimating the volume of gases evolved in a vacuum stability test method. The activation energy values computed using the Arrhenius equation and the Jacobs-Kureishy method were comparable and in the range 134–170 kJ mol^–1. In the temperature range 100–140, nitroglycerine volatilization was significant during the early stages of heating. Above 180, the rate of decomposition was very fast, leading to ignition of the propellant, followed by slow oxidation of the carbonaceous residues. The thermoanalytical data indicated a twostep decomposition process for propellant I, and a single-step process for propellant II.

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Zusammenfassung Untersuchungen der thermischen ReaktivitÄt von zwei Treibstoffkompositionen, die sich in ihrer chemischen Zusammensetzung, in ihren kalorimetrischen Werten und in der ballistischen Charakteristik signifikant unterscheiden, wurden im Temperaturbereich von 100–160C ausgeführt. Der Zersetzungsverlauf wurde nach zwei Methoden verfolgt: (i) durch Bestimmung der Bildungsgeschwindigkeit von nach der Methode von Bergman und Junk in Freheit gesetztem NO; (ii) durch Bestimmung des entwickelten Gases nach der VakuumstabilitÄtstestmethode. Die gemÄ\ der Arrhenius-Gleichung und nach der Jacobs-Kureishy-Methode bestimmten Werte für die Aktivierungsenergie sind vergleichbar und liegen im Bereich von 134–170 kJ mol^–1. Im Temperaturbereich von 100–140 C tritt wÄhrend des frühen Stadiums der Erhitzung eine signifikante Verflüchtigung von Nitroglycerin ein. Oberhalb 180 C verlÄuft die Zersetzung des Treibstoffs sehr schnell unter Verbrennung, woran sich eine langsame Oxydation des kohlenstoffreichen Rückstandes anschlie\t. Thermoanalytische Daten weisen darauf hin, da\ der Treibstoff I in zwei Schritten, der Treibstoff II jedoch in nur einem Schritt zersetzt wird.

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100–160 , , . : ) NO ) . , —, 134–170 · ^–1. 100– 140 . 180 , . I — II.

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The authors wish to thank Dr. Surjit Singh, Controller CI(ME) (now retired), for granting permission to publish this work, and Dr. K. R. K. Rao, Director, ERDL, for extending laboratory facilities for thermoanalytical and IR measurements. Thanks are also due to Dr. L. Prasad and Shri R. K. Devangan of IME, Bhandara, for their participation in the experimental work.     

Thermal decomposition properties of double-base propellant and ammonium perchlorate

The thermal decomposition properties and the heat of combustion (ΔH) of samples with different ammonium perchlorate (AP)/double base propellant (DB) mass ratios under argon atmosphere were studied by the thermogravimetry–differential scanning calorimetry–mass spectrometry–Fourier transform infrared spectroscopy (TG–DSC–MS–FTIR) and automatic calorimeter method. The results show that decomposition process of AP/DB samples in negative and zero oxygen balance (OB) is different from that in positive OB. With the increasing of AP in the AP/DB samples, the decomposition of the samples becomes more and more severe. When the OB of the samples is positive, the phenomenon of deflagration or explosion could be observed in the decomposition process. The sample with OB = 0 has the greatest heat of combustion.     

Effect of pressures on decomposition reaction kinetics of double-base propellant catalyzed with cerium citrate

The decomposition reaction kinetics of the double-base (DB) propellant (No. TG0701) composed of the mixed ester of triethyleneglycol dinitrate (TEGDN) and nitroglycerin (NG) and nitrocellulose (NC) with cerium(III) citrate (CIT-Ce) as a combustion catalyst was investigated by high-pressure differential scanning calorimetry (PDSC) under flowing nitrogen gas conditions. The results show that pressure (2 MPa) can decrease the peak temperature and increase the decomposition heat, and also can change the mechanism function of the exothermal decomposition reaction of the DB gun propellant under 0.1 MPa; CIT-Ce can decrease the apparent activation energy of the DB gun propellant by about 35 kJ mol⁻¹ under low pressure, but it can not display the effect under high pressure; CIT-Ce can not change the decomposition reaction mechanism function under a pressure.     

Efficient reduction of NOx emissions from waste double-base propellant in co-pyrolysis with pine sawdust

Co-pyrolysis technology containing biomass offers remarkable advantages in reducing NO_x emissions economically and efficiently. In this work, it was innovatively introduced to solve the problem of excessive NO_x emission during the incineration of waste energetic materials (EMs). The kinetics and NO_x emission characteristics of waste double-base propellant (DP), pine sawdust (PS), and their mixtures with different ratios during pyrolysis were investigated by thermogravimetric analysis and fixed-bed experiments. The results showed that there was a significant interaction between DP and PS. Kinetic analysis by Friedman and Kissinger-Akahira-Sunose (KAS) methods demonstrated that the average activation energies of the mixtures with different ratios were smaller than that of DP, indicating that the addition of PS improved the reactivity of co-pyrolysis. In addition, the fixed-bed experiment determined that the lowest NO_x emission was achieved during DP pyrolysis alone at 900 ℃. Co-pyrolysis at this temperature was found to have synergistic effects of reduced NO_x emissions for different ratios of mixtures. The best synergistic effect was achieved at the mixing ratio of 60 wt% DP and 40 wt% PS, resulting in a 72.11 % reduction in actual NO_x emissions compared to the expected value. This study provides a new direction and powerful data support for the clean, efficient and economic treatment of waste EMs, especially for practical engineering strategies.     

Direct asymmetric aldol reaction catalyzed by nanocrystalline magnesium oxide

Nanomaterials with their three-dimensional structure and defined size and shape are considered to be suitable candidates for proper alignment with prochiral substrates for unidirectional introduction of reacting species to induce an asymmetric centre. The reusable and suitably aligned nanocrystalline magnesium oxide catalyzed direct asymmetric aldol reaction afforded the chiral β-hydroxy carbonyl compounds in good yields and moderate ee's.     

Thermal behavior of carbon nanotubes decorated with gold nanoparticles

Three different forms of carbon, i.e., multi-walled carbon nanotubes (CNTs), single-walled CNTs, and soot, were decorated with gold nanoparticles by a new method. In this method C₁₀H₈ ⁻ ions transfer electrons to the CNTs or soot. These electrons on the carbon surface can then reduce Au³⁺ species to form supported Au nanoparticles with a narrow particle size distribution. Thermogravimetric/differential thermal analyses (TG/DTA), XRD, Raman, and TEM show that naphthalene molecules remain trapped inside the Au nanoparticles and can only be removed by treatment at ca. 300 °C. Remarkable effect of the Au nanoparticles on the oxidation of carbon by O₂ is also observed by TG/DTA, i.e., on-set oxidation temperature and activation energy (E _a). It is shown that as the Au particle size decreases from 25 to 2 nm a linear decrease of the oxidation temperature is observed. Au particles larger than 25 nm do not produce any significant effect on carbon oxidation. These results are discussed in terms of spillover catalytic effect where Au nanoparticles activate O₂ molecules to produce active oxygen species which oxidize the different carbon supports.     

The structure and dynamics of hydrated and hydroxylated magnesium oxide nanoparticles

An understanding of the structure of water on metal oxide nanoparticles is important due to its involvement in a number of surface processes, such as in the modification of transport near surfaces and the resulting impact on crystal growth and dissolution. However, as direct experimental measurements probing the metal oxide-water interface of nanoparticles are not easily performed, we use atomistic simulations using experimentally derived potential parameters to determine the structure and dynamics of the interface between magnesium oxide nanoparticles and water. We use a simple strategy to generate mineral nanoparticles, which can be applied to any shape, size, or composition. Molecular dynamics simulations were then used to examine the structure of water around the nanoparticles, and highly ordered layers of water were found at the interface. The structure of water is strongly influenced by the crystal structure and morphology of the mineral and the extent of hydroxylation of the surface. Comparison of the structure and dynamics of water around the nanoparticles with their two-dimensional flat surface counterparts revealed that the size, shape, and surface composition also affects properties such as water residence times and coordination number.     

Copper oxide nanoparticles catalyzed vinylation of imidazoles with vinyl halides under ligand-free conditions

Recyclable copper oxide nanoparticles catalyzed most efficient and straightforward protocol for the vinylation of imidazoles with vinyl halides under ligand-free conditions. Utilizing this protocol various imidazoles were cross-coupled with different substituted vinyl halides to get the corresponding products in excellent yields with the retention configuration.     

Regioselective oxyalkylation of vinylarenes catalyzed by diatomite-supported manganese oxide nanoparticles

A regioselective oxyalkylation reaction of vinylarenes with cyclic ethers was developed under the catalysis of a new heterogeneous catalyst, the diatomite-supported Mn(3)O(4) nanoparticles (SMONP-1). The use of this heterogeneous catalyst provided a novel approach for the synthesis of α-carbonyled β-alkylated aryl derivatives via a sp(3) C-H bond functionalization under mild aerobic conditions.     

Thermal behavior of oxidation of TiN and TiC nanoparticles

Titanium nitride and carbide oxidation have been studied using TG and DSC. Titanium nitride shows a oxidation behavior were both techniques detect a unique phenomenon. Titanium carbide shows a variable behavior depending on the heating rate and sample size. Low masses and heating rates provide similar results to titanium nitride. However, using moderate sample sizes and scanning rates a two-stage oxidation is observed. The first step is extremely fast and exothermic, consuming the oxygen trapped inside the nanoparticle bed. The second is controlled by the diffusion of the oxygen and CO₂ through the sample. Thermal safety conclusions are extracted from this observation. Energies of activation calculated using traditional kinetic models are lower than those found in the literature, being an indication of the influence of the specific surface of the material.     

Thermal and plasma synthesis of metal oxide nanoparticles from MOFs with SERS characterization

Aluminum oxide (Al₂O₃) and chromium oxide (Cr₂O₃) nanoparticles were synthesized by thermolysis of metal-organic frameworks (MOFs). Further O₂ plasma treatment is required to obtain high crystalline quality metal oxides. The composition and morphology of metal oxide nanoparticles were confirmed by powder X-ray diffraction and scanning electron microscopy characterization, respectively. The quality of synthesized metal oxides was also examined by observing the surface-enhanced Raman scattering (SERS) spectra of methyl orange adsorbed on Al₂O₃ and Cr₂O₃. The observed SERS effect can be ascribed to charge-transfer (CT) resonance effect between methyl orange and metal oxide surfaces. UV–vis absorption spectra and DFT calculations of metal oxide- methyl orange complexes have confirmed that the observed SRS effect is due to CT resonance between the metal oxide nanoparticles and the adsorbed methyl orange molecules.     

Michael addition of 1,3-dicarbonyl compounds catalyzed by iron oxide nanoparticles

Several iron oxides nanoparticles (Fe₂O₃@Fe₂O₃, Fe°@Fe₂O₃, GO@Fe₂O₃ and calcinated Fe₂O₃) have been assessed as catalysts in the 1,4-addition of a cyclic β-ketoester onto methyl vinyl ketone under neat conditions. It appeared that calcinated Fe₂O₃NP are efficient catalysts at 1?mol% loading for the Michael addition of 1,3-dicarbonyl compounds onto various enones.     

Thermochemical properties and thermokinetic behavior of energetic triazole ionic salts

The properties of dissolution in different solvents,the specific heat capacity and thermal decomposition process under the non-isothermal conditions for energetic triazole ionic salts 1,2,4-triazolium nitrate(1a),1,2,3-triazolium nitrate(1b),3,4,5triamino-1,2,4-triazolium nitrate(2a),3,4,5-triamino-1,2,4-triazolium dinitramide(2b)were precisely measured using a Calvet Microcalorimeter.The thermochemical equation,differential enthalpies of dissolution(△difH m ),standard molar enthalpies of dissolution(△difH ...     

三唑含能离子盐的热化学性质和热动力学行为

用微量热技术测量1,2,4-三唑硝酸盐(1a)、1,2,3-三唑硝酸盐(1b)、3,4,5-三氨基-1,2,4-三唑硝酸盐(2a)、3,4,5-三氨基-1,2,4-三唑二硝酰胺盐(2b)4种三唑类含能离子盐的溶解过程热效应、比热容(283KT353K)及非等温条件下的热分解过程.用处理实验数据和理论计算方法获得了1a、1b、2a、2b溶解过程的热化学方程式、微分溶解焓、摩尔溶解焓、动力学方程式、活化能、指前因子、283～353K温区内比热容随温度变化的线性关系式、标准摩尔热容CpΘ,m和285～353K温区以298.15K为基准的焓、熵和Gibbs自由能函数值.计算了热分解反应的动力学参数、热力学参数以及评估了1a、1b、2a、2b对热的抵抗能力.得到了化合物性质与分子结构之间内在关系的信息.     

Reaction of magnesium oxide and magnesium silicates with ammonium hydrodifluoride

The reactions of magnesium oxide and magnesium silicates (forsterite and serpentines) with ammonium hydrodifluoride is studied using DTA, X-ray powder diffraction, and IR spectroscopy. The conditions for the formation of intermediate phases are determined. The structure of the silicate mineral does not significantly affect the fluorination.     

Antibacterial study of Eucalyptus grandis fabricated zinc oxide and magnesium doped zinc oxide nanoparticles and its characterization

Mg-doped zinc oxide and zinc oxide nanoparticles were prepared by using methanolic seed extract from the Eucalyptus grandis plant via a green approach. Phytoconstituents present in seed extract act as capping and stabilizing agents for the biosynthesis of nanoparticles. Doping of Mg to zinc oxide nanoparticles increases the bandgap energy, thus enhancing its chemical, physical and optical properties. Further, it was characterized by various techniques such as scanning electron microscopy giving morphological information about the wurtzite hexagonal structure of bio-synthesized nanoparticles. X-ray diffraction technique tells about the crystalline nature of particles and the average crystallite size for zinc oxide and doped zinc oxide nanoparticles. Mg as a dopant enhances the properties of nanoparticles, thus making it more efficiently applicable as an antibacterial agent against Escherichia coli, gram-negative bacteria.     

Nickel oxide nanoparticles catalyzed synthesis of poly-substituted quinolines via Friedlander hetero-annulation reaction

Reusable acidic nickel oxide nanoparticles have been synthesized,characterized and applied as a catalyst to convert 2-aminoaryl ketones and β-ketoesters/ketones into the corresponding quinolines in good yields with high selectivity.This could serve as a simple and convenient procedure for the Friedlander annulations.     

Thermal oxidative degradation of isotactic polypropylene catalyzed by copper and copper oxide interfaces

The oxidative degradation of isotactic polypropylene films coated on well-defined Cu(Cu₂O), CuO_0.67, and CuO films in a temperature range of 90–120°C in a quartz-spoon-gauge-reaction vessel was studied. This catalytic reaction has been compared with the oxidation of polypropylene without copper or oxide films. The reaction vessel contained, if needed, P₂O₅ and/or KOH as “getters” for H₂O and CO₂, these substances could be menitored continuously. Cu(Cu₂O) films were transformed during oxidation of the polymer to yellow CuO_0.67 below 100°C and above this temperature to black CuO in the presence of H₂O and CO₂, whereas in the absence of these compounds CuO was formed below 100°C and CuO_0.67 at 120°C. Characteristic autoxidation curves obtained in the absence of H₂O and CO₂ showed induction periods that were shorter for copper oxide-polymer interfaces than for glass-polymer interfaces (i.e., for uncatalyzed oxidation). Abnormalities were observed for Cu(Cu₂O)-polymer interfaces because of further oxidation of Cu during the reaction. The rates of oxygen consumption were faster for CuO_0.67-polymer and CuO-polymer than for the uncatalyzed reaction; the catalytic action of CuO_0.67 was somewhat larger than that of CuO. The important observation was made that the mechanism of oxidation is not the same in the absence and presence of reaction products; that is, H₂O and CO₂. This was confirmed by ion beam scattering experiments, which also revealed that an oxidation-reduction process takes place at Cu and their oxide interfaces. A mechanism for the catalytic oxidation process, based on the ease by which copper ions are released from the metal oxides at the interface, was formulated. These ions diffuse subsequently as actions of carboxylate anions into the bulk of the polymer. Arrhenius equations of oxygen consumption are given for all cases; the energy of activation calculated for the initiation of the uncatalyzed oxidation agrees with its literature value. The energy of activation for the initiation of the catalyzed reaction was a few kilocalories lower than that for the uncatalyzed reaction. Catalytic action is mainly operative for the initiation reaction at the interface and for the decomposition of hydroperoxides by copper ions. Preventing the delivery of copper ions to the polymer would be the most efficient way of inhibiting the catalysis.     

Copper oxide nanoparticles catalyzed synthesis of aryl sulfides via cascade reaction of aryl halides with thiourea

Recyclable copper oxide nanoparticles catalyzed simple and highly efficient protocol for the synthesis of symmetrical aryl sulfides was developed by the cross-coupling of aromatic halides with inexpensive and commercially available thiourea which was used as an effective sulfur surrogate. The present cross-coupling protocol of thiourea, via cascade reaction with various substituted aryl halides, producing desired aryl sulfides, has an added advantage of avoiding foul-smelling thiols.