Journal articles: 'Enthalpy decomposition'

1

Maitra, S., N. Chakrabarty, and J. Pramanik. "Decomposition kinetics of alkaline earth carbonates by integral approximation method." Cerâmica 54, no. 331 (2008): 268–72. http://dx.doi.org/10.1590/s0366-69132008000300001.

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The decomposition kinetics of four synthetic alkaline earth metal carbonates (MgCO3, CaCO3, SrCO3 and BaCO3) was studied under non-isothermal conditions from thermo-gravimetric measurements as compared to. The integral approximation method of Coats and Redfern was used to determine the kinetic parameters for the decomposition processes. The decomposition reactions followed mostly first order kinetics and the activation energy of the decomposition reactions increased with the increase in the molecular mass of the carbonates. The change in enthalpy for the decomposition processes was also calculated and compared with the activation energies for the decomposition processes. The activation energy of the decomposition process for all the carbonates was higher than the enthalpy of the reaction excepting SrCO3.

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Dunaev, Anatoliy M., Vladimir B. Motalov, Mikhail A. Korobov, Dmitrii Govorov, Victor V. Aleksandriiskii, and Lev S. Kudin. "Vapor Composition and Vaporization Thermodynamics of 1-Ethyl-3-methylimidazolium Hexafluorophosphate Ionic Liquid." AppliedChem 3, no. 2 (2023): 303–19. http://dx.doi.org/10.3390/appliedchem3020019.

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The processes of the sublimation and thermal decomposition of the 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid (EMImPF6) were studied by a complex approach including Knudsen effusion mass spectrometry, IR and NMR spectroscopy, and quantum chemical calculations. It was established that the vapor over the liquid phase primarily consists of decomposition products under equilibrium conditions. Otherwise, the neutral ion pairs are the only vapor components under Langmuir conditions. To identify the nature of the decomposition products, an experiment on the distillation of the ionic liquid was performed and the collected distillate was analyzed. It was revealed by the IR and NMR spectroscopy that EMImPF6 decomposes to substituted imidazole-2-ylidene (C6N2H10PF5) and HF. The measured vapor pressure of C6N2H10PF5 reveals a very low activity of the decomposition products (<10−4) in the liquid phase. The absence of a significant accumulation of decomposition products in the condensed phase makes it possible to determine the enthalpy of sublimation of the ionic liquid assuming its unchanged activity. The thermodynamics of the EMImPF6 sublimation was studied by Knudsen effusion mass spectrometry. The formation enthalpy of EMImPF6 in the ideal gas state was found from a combination of the sublimation enthalpy and formation enthalpy of the ionic liquid in the condensed state. The obtained value is in good agreement with those calculated by quantum chemical methods.

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Kirilov, P. P., I. N. Gruncharov, and Y. G. Pelovski. "Enthalpy of thermal decomposition of pyrite concentrate." Thermochimica Acta 244 (October 1994): 79–83. http://dx.doi.org/10.1016/0040-6031(94)80208-4.

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MUSUC, Adina Magdalena, and Dumitru OANCEA. "The structure-activity relationships from DSC data." Revue Roumaine de Chimie 66, no. 2 (2021): 161–66. http://dx.doi.org/10.33224/rrch.2021.66.2.06.

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The differential scanning calorimetry becomes nowadays an easily available technique able to provide experimental data which can be used to seek for possible correlations with molecular properties. Among these data, the entropy and enthalpy for different phase transition like melting or decomposition of various related compounds proved to be very fruitful. In the present paper, the enthalpy and entropy data for different phase transitions and decomposition of two classes of related energetic compounds (13 based on phenoxazone derivatives and 6 on substituted (E)-3-(azulen-1-yldiazenyl)-1,2,5-oxadiazole) are analyzed and presented. The heats of decomposition seem to present no correlations as functions of molecular mass or melting temperature, while the heats of melting and the temperatures of melting present a fair correlation as a function of the molecular mass or melting temperature. A particularly good correlation is provided by the entropy of melting as a function of the enthalpy of melting, in accord with their significance for a process at equilibrium.

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Dubrawski, J. V., and S. St J. Warne. "Differential Scanning Calorimetry of Minerals of the Dolomite-Ferroan-Dolomite-Ankerite Series in Flowing Carbon Dioxide." Mineralogical Magazine 52, no. 368 (1988): 627–35. http://dx.doi.org/10.1180/minmag.1988.052.368.07.

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AbstractThe dolomite-ferroan-dolomite-ankerite series of carbonate minerals has been investigated in flowing carbon dioxide using high-temperature DSC. Decomposition products were analysed by X-ray diffraction. The minerals studied included dolomite containing no iron, and members substituted by iron in the molar ratio range of 0.082 to 0.49. Complete resolution of the three main endothermic features was observed and enthalpy values ΔH, determined from each. The individual and total enthalpy values showed a linear dependence upon the Fe and Mg content of the members across the series. A decrease in the enthalpy of decomposition occurs with increasing Fe content. The effect of Fe substitution was readily observed and the estimated limit of detection is less than 1% FeO. Accuracy of the measurements was limited by the purity of the minerals themselves.

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Mahon, Daniel, Gianfranco Claudio, and Philip Eames. "An Experimental Study of the Decomposition and Carbonation of Magnesium Carbonate for Medium Temperature Thermochemical Energy Storage." Energies 14, no. 5 (2021): 1316. http://dx.doi.org/10.3390/en14051316.

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To improve the energy efficiency of an industrial process thermochemical energy storage (TCES) can be used to store excess or typically wasted thermal energy for utilisation later. Magnesium carbonate (MgCO3) has a turning temperature of 396 °C, a theoretical potential to store 1387 J/g and is low cost (~GBP 400/1000 kg). Research studies that assess MgCO3 for use as a medium temperature TCES material are lacking, and, given its theoretical potential, research to address this is required. Decomposition (charging) tests and carbonation (discharging) tests at a range of different temperatures and pressures, with selected different gases used during the decomposition tests, were conducted to gain a better understanding of the real potential of MgCO3 for medium temperature TCES. The thermal decomposition (charging) of MgCO3 has been investigated using thermal analysis techniques including simultaneous thermogravimetric analysis and differential scanning calorimetry (TGA/DSC), TGA with attached residual gas analyser (RGA) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) (up to 650 °C). TGA, DSC and RGA data have been used to quantify the thermal decomposition enthalpy from each MgCO3.xH2O thermal decomposition step and separate the enthalpy from CO2 decomposition and H2O decomposition. Thermal analysis experiments were conducted at different temperatures and pressures (up to 40 bar) in a CO2 atmosphere to investigate the carbonation (discharging) and reversibility of the decarbonation–carbonation reactions for MgCO3. Experimental results have shown that MgCO3.xH2O has a three-step thermal decomposition, with a total decomposition enthalpy of ~1050 J/g under a nitrogen atmosphere. After normalisation the decomposition enthalpy due to CO2 loss equates to 1030–1054 J/g. A CO2 atmosphere is shown to change the thermal decomposition (charging) of MgCO3.xH2O, requiring a higher final temperature of ~630 °C to complete the decarbonation. The charging input power of MgCO3.xH2O was shown to vary from 4 to 8136 W/kg with different isothermal temperatures. The carbonation (discharging) of MgO was found to be problematic at pressures up to 40 bar in a pure CO2 atmosphere. The experimental results presented show MgCO3 has some characteristics that make it a candidate for thermochemical energy storage (high energy storage potential) and other characteristics that are problematic for its use (slow discharge) under the experimental test conditions. This study provides a comprehensive foundation for future research assessing the feasibility of using MgCO3 as a medium temperature TCES material. Future research to determine conditions that improve the carbonation (discharging) process of MgO is required.

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Zhou, F., Y. T. Chou, and E. J. Lavernia. "Decomposition and thermodynamic property of metastable Fe–Zn solid solutions produced by mechanical alloying." Journal of Materials Research 17, no. 12 (2002): 3230–36. http://dx.doi.org/10.1557/jmr.2002.0467.

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Thermal decomposition of supersaturated single-phase body-centered cubic (bcc) Fe100−xZnx (5≤ x ≤65 at.%) solid solutions, processed via mechanical alloying of high-purity metal powders, was investigated using x-ray diffraction and differential scanning calorimetry (DSC). At elevated temperatures the metastable solid solution decomposed into a stable equilibrium aggregate consisting of the pure bcc Fe phase and an intermetallic compound Fe4Zn9. The decomposition temperature decreased with increasing Zn concentration. The enthalpy of decomposition for various Fe–Zn solid solutions measured by the DSC was in the range of 1.2–3.5 kJ/mol. The enthalpy of mixing of the as-milled solid solutions from elemental Fe and Zn powders was estimated to be 0.5–1.7 kJ/mol. In addition, the activation energies of decomposition for these solid solutions were determined on the basis of the Kissinger analysis, and their values appeared to be independent of the Zn concentration in the alloy, with an average of 147 ± 17 kJ/mol.

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Humphries, Terry D., Motoaki Matsuo, Guanqiao Li, and Shin-ichi Orimo. "Complex transition metal hydrides incorporating ionic hydrogen: thermal decomposition pathway of Na2Mg2FeH8 and Na2Mg2RuH8." Physical Chemistry Chemical Physics 17, no. 12 (2015): 8276–82. http://dx.doi.org/10.1039/c5cp00258c.

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The optimised syntheses of Na2Mg2FeH8 and Na2Mg2RuH8 are reported and their thermal decomposition pathways established. The enthalpy and entropy of each decomposition step has been determined by PCI measurements.

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Zhang, Yubin, Zhengsong Qiu, Jiaxing Mu, et al. "Intelligent Temperature-Control of Drilling Fluid in Natural Gas Hydrate Formation by Nano-Silica/Modified n-Alkane Microcapsules." Nanomaterials 11, no. 9 (2021): 2370. http://dx.doi.org/10.3390/nano11092370.

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Inhibiting hydrate decomposition due to the friction heat generated by the drilling tools is one of the key factors for drilling hydrate formation. Since the existing method based on chemical inhibition technology can only delay the hydrate decomposition rate, a phase-change microcapsule was introduced in this paper to inhibit, by the intelligent control of the drilling fluid temperature, the decomposition of the formation hydrate, which was microencapsulated by modified n-alkane as the core material, and nano-silica was taken as the shell material. Scanning electron microscope (SEM), size distribution, X-ray diffraction (XRD), and Fourier transform infrared spectrometer (FT-IR) were utilized to characterize the structural properties of microcapsules. Differential scanning calorimetry (DSC) spectra displayed that the latent heat was 136.8 J/g in the case of melting enthalpy and 136.4 J/g in the case of solidification enthalpy, with an encapsulation efficiency of 62.6%. In addition, the prepared microcapsules also showed good thermal conductivity and reliability. By comparison, it was also proved that the microcapsules had good compatibility with drilling fluid, which can effectively control the temperature of drilling fluid for the inhibition of hydrate decomposition.

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10

Kiselev, Vitaly G. "Comment on “Decomposition mechanisms of trinitroalkyl compounds: a theoretical study from aliphatic to aromatic nitro compounds” by G. Fayet, P. Rotureau, B. Minisini, Phys. Chem. Chem. Phys., 2014, 16, 6614." Physical Chemistry Chemical Physics 17, no. 15 (2015): 10283–84. http://dx.doi.org/10.1039/c4cp04999c.

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The approach proposed in the original paper yields spurious contributions to both enthalpy and entropy of activation of barrierless reactions. This renders reaction branching ratios intrinsically biased towards radical decomposition of nitro species.

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11

Ranade, M. R., F. Tessier, A. Navrotsky, and R. Marchand. "Calorimetric determination of the enthalpy of formation of InN and comparison with AlN and GaN." Journal of Materials Research 16, no. 10 (2001): 2824–31. http://dx.doi.org/10.1557/jmr.2001.0389.

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The standard enthalpy of formation of InN at 298 K has been determined using high-temperature oxidative drop solution calorimetry in a molten sodium molybdate solvent at 975 K. Calorimetric measurements were performed on six InN samples with varying nitrogen contents. The samples were characterized using x-ray diffraction, chemical analysis, electron microprobe analysis, and Brunauer–Emmett–Teller surface area measurement. The variation of the enthalpy of drop solution (kJ/g) with nitrogen content is approximately linear. The data, when extrapolated to stoichiometric InN, yield a standard enthalpy of formation from the elements of ?28.6 ± 9.2 kJ/mol. The relatively large error results from the deviation of individual points from the straight line rather than uncertainties in each set of data for a given sample. This new directly measured enthalpy of formation is in good agreement with the old combustion calorimetric result by Hahn and Juza (1940). However, this calorimetric enthalpy of formation is significantly different from the enthalpy of formation values derived from the temperature dependence of the apparent decomposition pressure of nitrogen over InN. A literature survey of the enthalpies of formation of III–N nitride compounds is presented.

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12

Cabral, F. A. O., S. Gama, and C. A. Ribeiro. "Activation energy and enthalpy of decomposition for the Fe17Sm2 nitride." Journal of Applied Physics 81, no. 8 (1997): 5109–11. http://dx.doi.org/10.1063/1.365152.

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13

Jabłoński, Maciej, Krzysztof Lubkowski, Sandra Tylutka, and Andrzej Ściążko. "Heat effects in the reaction of sulfuric acid with ilmenites influenced by initial temperature and acid concentration." Polish Journal of Chemical Technology 23, no. 3 (2021): 37–42. http://dx.doi.org/10.2478/pjct-2021-0028.

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Abstract The influence of temperature and sulfuric acid concentration on the enthalpy and the rate of heat release during the reaction of Norwegian and Australian ilmenites with sulfuric acid was determined. The experimental results obtained from calorimetric measurements were compared with theoretical calculations based on the oxide composition and the phase composition of the raw material. Experimentally determined heat of reaction for Norwegian ilmenite (900–940 kJ/kg) and Australian ilmenite (800–840 kJ/kg) showed good agreement with theoretical calculations based on the phase composition of the raw material. It was found that the enthalpy of ilmenites decomposition reaction does not depend on the concentration of sulfuric acid in the concentration range from 83% to 93%. It was also demonstrated that the temperature and concentration of sulfuric acid have a significant impact on the thermokinetics of the decomposition process, increasing the value of the average rate of temperature change.

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VG, Gavriljuk. "Electron structure and thermodynamics of solid solutions in Ni–H system." Material Science & Engineering International Journal 2, no. 4 (2018): 101–9. http://dx.doi.org/10.15406/mseij.2018.02.00042.

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The widespread concept of nickel hydride in the Ni–H system is discussed based on the first–principle atomic calculations and experimental X–ray diffraction data. The total cohesion energy in Ni–H solid solution has been determined using the density functional theory and program package Wien2k. Its dependence on hydrogen concentration is shown to be linear, which suggests the absence of any energy barrier for precipitation reaction. Moreover, the second derivative of the calculated solution enthalpy is negative within the hydrogen–to–nickel ratios, H/Ni, of 0.03 to 0.75, which is a sign of spinodal decomposition. These hydrogen concentrations are consistent with the measurements of X–ray diffraction, of which results are traditionally interpreted in terms of Ni hydride. The density of electron states has been calculated, and its non–monotonous concentration dependence correlates with that of solution enthalpy, which is also expected for spinodal decomposition. The obtained results are interpreted as miscibility gap in the Ni–H system with spinodal decomposition having the electron origin. In addition, using mechanical spectroscopy, the strain dependent internal friction has been observed in the hydrogen–charged nickel with H/Ni ratio of about 0.7. This effect is controlled by irreversible plastic deformation, which is typical for solid solutions, not for brittle chemical compounds. Finally, the “hydrides” in a number of metals are discussed in terms of two Gibb’s types of precipitation reactions. Keywords: nickel, hydrogen, ab initio calculations, spinodal decomposition, hydride

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Nagle, John F., and Martin Goldstein. "Decomposition of entropy and enthalpy for the melting transition of polyethylene." Macromolecules 18, no. 12 (1985): 2643–52. http://dx.doi.org/10.1021/ma00154a047.

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Oppermann, H., H. Göbel, P. Schmidt, H. Schadow, and V. Vassilev. "Thermochemische Untersuchungen am System Bi/Se/O III. Zum quasibinären System Bi2O3 –Bi2Se3 und zum ternären Bereich Bi2O3– Bi2O2Se – Se – SeO2/Thermochemical Investigations on the System Bi/Se/O III.The Quasy Binary System Bi2O3-Bi2Se3and the Ternary Range Bi2O3-Bi2O2Se–Se–SeO2." Zeitschrift für Naturforschung B 54, no. 2 (1999): 261–69. http://dx.doi.org/10.1515/znb-1999-0215.

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Only the ternary phase Bi2O2Se is shown to exists in the thermodynamical equilibrium in the investigated ternary system on the binary line Bi2O3-Bi2Se3. Its thermal decomposition was measured in a quartz membrane zero manometer. The enthalpy of formation and the standard entropy were derived from the temperature function of the decomposition equilibrium:⊿H°f(Bi2O2Ses,298) = -104,6 ±4,0 kcal/molS°(Bi2O2Ses,298) = 43 ± 3 cal/K·mol.The coexistence ranges in the ternary region Bi2O3- SeO2- Bi2O2Se-Se were followed by X-ray diffraction, IR spectroscopy and total pressure measurements of binary and ternary compositions.

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van Odyck, Daniel E. A., John B. Bell, Franck Monmont, and Nikolaos Nikiforakis. "The mathematical structure of multiphase thermal models of flow in porous media." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 465, no. 2102 (2008): 523–49. http://dx.doi.org/10.1098/rspa.2008.0268.

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This paper is concerned with the formulation and numerical solution of equations for modelling multicomponent, two-phase, thermal fluid flow in porous media. The fluid model consists of individual chemical component (species) conservation equations, Darcy's law for volumetric flow rates and an energy equation in terms of enthalpy. The model is closed with an equation of state and phase equilibrium conditions that determine the distribution of the chemical components into phases. It is shown that, in the absence of diffusive forces, the flow equations can be split into a system of hyperbolic conservation laws for the species and enthalpy and a parabolic equation for pressure. This decomposition forms the basis of a sequential formulation where the pressure equation is solved implicitly and then the component and enthalpy conservation laws are solved explicitly. A numerical method based on this sequential formulation is presented and used to demonstrate some typical flow behaviour that occurs during fluid injection into a reservoir.

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Wen, Pu Hong. "Kinetic Investigation of Thermal Decomposition Reactions of 4'-Demethypodophyllotoxin and Podophyllotoxin." Advanced Materials Research 800 (September 2013): 517–21. http://dx.doi.org/10.4028/www.scientific.net/amr.800.517.

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The thermal behavior and thermal decomposition kinetic parameters of podophyllotoxin (PPT) and 4-demethypodophyllotoxin (DMPPT) in a temperature-programmed mode have been investigated by means of DSC and TG-DTG. The kinetic model functions in differential and integral forms of the thermal decomposition reactions mentioned above for leading stage were established. The kinetic parameters of the apparent activation energy Ea and per-exponential factor A were obtained from analysis of the TG-DTG curves by integral and differential methods. The most probable kinetic model function of both decomposition reactions in differential form was (1-α) 2. The values of Ea indicated that the reactivity of PPT was higher than that of DMPPT in the thermal decomposition reaction. The values of the entropy of activation ΔS≠, enthalpy of activation ΔH≠ and free energy of activation ΔG≠ of the reactions were estimated.

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Mishra, M. K., and R. K. Singh. "SYNTHESIS, SPECTROSCOPIC CHARACTERISATION, AND KINETIC PARAMETER STUDY OF LABILE CHROMIUM COMPLEXES USING BENZOIC ACID AS A LIGAND." RASAYAN Journal of Chemistry 15, no. 04 (2022): 2436–41. http://dx.doi.org/10.31788/rjc.2022.1548040.

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Ethanol was used as the solvent in the process of producing chromium benzoic acid complexes by combining CrO3 (chromium trioxide) and benzoic acid. Its spectrum characteristics were evaluated by the use of elemental analysis, FAB-Mass Spectroscopy,1 HNMR spectroscopy, FTIR Spectroscopy, UV-Vis Spectroscopy, and ICP-OES, and its thermal decomposition has been studied through DSC. The Objective was to get inside of thermal stability, the heat of energy, and the rate of decomposition of the complexes. The kinetic parameter, low amount of activation energy, and enthalpy of reaction, all pointed to the complexes having a high degree of liability.

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Graetz, Jason. "Metastable Metal Hydrides for Hydrogen Storage." ISRN Materials Science 2012 (December 20, 2012): 1–18. http://dx.doi.org/10.5402/2012/863025.

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The possibility of using hydrogen as a reliable energy carrier for both stationary and mobile applications has gained renewed interest in recent years due to improvements in high temperature fuel cells and a reduction in hydrogen production costs. However, a number of challenges remain and new media are needed that are capable of safely storing hydrogen with high gravimetric and volumetric densities. Metal hydrides and complex metal hydrides offer some hope of overcoming these challenges; however, many of the high capacity “reversible” hydrides exhibit a large endothermic decomposition enthalpy making it difficult to release the hydrogen at low temperatures. On the other hand, the metastable hydrides are characterized by a low reaction enthalpy and a decomposition reaction that is thermodynamically favorable under ambient conditions. The rapid, low temperature hydrogen evolution rates that can be achieved with these materials offer much promise for mobile PEM fuel cell applications. However, a critical challenge exists to develop new methods to regenerate these hydrides directly from the reactants and hydrogen gas. This spotlight paper presents an overview of some of the metastable metal hydrides for hydrogen storage and a few new approaches being investigated to address the key challenges associated with these materials.

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21

Marzzacco, Charles J. "The Enthalpy of Decomposition of Hydrogen Peroxide: A General Chemistry Calorimetry Experiment." Journal of Chemical Education 76, no. 11 (1999): 1517. http://dx.doi.org/10.1021/ed076p1517.

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Cataldo, Franco. "Thermal stability, decomposition enthalpy, and Raman spectroscopy of 1-alkene secondary ozonides." Tetrahedron Letters 56, no. 8 (2015): 994–98. http://dx.doi.org/10.1016/j.tetlet.2015.01.056.

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Lopez-Delgado, A., O. Garcia-Martinez, and M. J. Torralvo-Fernandez. "Preparation and characterization of LaOHSO4-thermal decomposition and standard enthalpy of formation." Journal of the Less Common Metals 149 (April 1989): 109–14. http://dx.doi.org/10.1016/0022-5088(89)90477-3.

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Mathieu, Didier. "Significance of Theoretical Decomposition Enthalpies for Predicting Thermal Hazards." Journal of Chemistry 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/158794.

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Much effort is currently put into the development of models for predicting decomposition enthalpies measured using differential scanning calorimetry (DSC). As an alternative to the purely empirical schemes reported so far, this work relies on theoretical values obtained on the basis of simple assumptions. For nitroaromatic compounds (NACs) studied in sealed sample cells, our approach proves clearly superior to previous ones. In contrast, it correlates poorly with data measured in pin-hole sample cells. Progress might be obtained through a combination of the present approach with the usual Quantitative Structure-Property Relationships (QSPR) methodologies. This work emphasizes the significance of the theoretical decomposition enthalpy as a fundamental descriptor for the prediction of DSC values. In fact, the theoretical value provides a valuable criterion to characterize thermal hazards, as a complement to experimental decomposition temperatures.

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Jorge, Nelly Lidia, Alexander German Bordón, Andrea Natalia Pila, et al. "Thermal decomposition of 3,6-diphenyl-1,2,4,5-tetroxane in nitromethane solution." JOURNAL OF ADVANCES IN CHEMISTRY 15, no. 2 (2018): 6306–10. http://dx.doi.org/10.24297/jac.v15i2.7961.

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The thermal decomposition reaction of benzaldehyde diperoxide (DFT; 0.001 mol L-1) in nitromethane solution studied in the temperature range of 130.0-166.0 °C, follows a first-order kinetic law up to at least 60% DFT conversion. The organic products observed were benzaldheyde and benzoic acid. A stepwise mechanism of decomposition was proposed where the first step is the homolytic unimolecular rupture of the O-O bond. The activation enthalpy and activation entropy for DFT in nitromethane were calculated (DH# = 106.3 ± 1.0 kJ mol-1 and DS# = -58.6 ± 1.1 J mol-1K-1) and compared with those obtained in other solvents to evaluate the solvent effect.

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Dychtoń, Kamil, Roman Przeliorz, Marek Góral, and Jan Sieniawski. "Thermal Analysis of Halide Activator Used in Aluminizing of TiAl Intermetallics." Key Engineering Materials 592-593 (November 2013): 473–76. http://dx.doi.org/10.4028/www.scientific.net/kem.592-593.473.

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A detailed study of thermal analysis of ZrCl4 was carried out to investigate the influence of the halide salt type activator on the growth behavior of coating formed in vapor phase aluminizing process and subsequently to identify the most suitable condition. The equilibrium partial pressures of vapor species generated at the decomposition temperature of ZrCl4 were calculated by using a procedure based on minimization of the whole Gibbs energy with Factsage 6.2 using Fact 53 and SGsold thermodynamic databases. The results were discussed and compared with literatures. With the aid of thermodynamic analytical tools, chloride salt activator was analysed and the decomposition temperature with related enthalpy change was evaluated.

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Karapınar, Emin, Ilkay Hilal Gubbuk, Bilge Taner, Pervin Deveci, and Emine Ozcan. "Thermal Degradation Behaviour of Ni(II) Complex of 3,4-Methylenedioxaphenylaminoglyoxime." Journal of Chemistry 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/548067.

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Thermal degradation behaviour of the Ni(II) complex of 3,4-methylenedioxaphenylaminoglyoxime was investigated by TG, DTA, and DTG at a heating rate of 10°C min−1under dinitrogen. The acquired experimental data shows that the complex is thermally stable up to 541 K. The pyrolytic decomposition process occurs by melting metal complex and metal oxide remains as final product. The energies of the reactions involved and the mechanism of decomposition at each stage have been examined. The values of kinetic parameters such as activation energy (E), preexponential factor (A) and thermodynamic parameters such as enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG) are also evaluated.

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Horozova, Elena, Nina Dimcheva, and Zinaida Jordanova. "Enzyme-Catalyzed Decomposition of Dibenzoyl Peroxide in Organic Solvents." Zeitschrift für Naturforschung C 56, no. 7-8 (2001): 553–58. http://dx.doi.org/10.1515/znc-2001-7-813.

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Catalytic activity of catalase (CAT, EC 1.11.1.6), immobilized on carbon black NORIT and soot PM-100, with respect to decomposition of dibenzoyl peroxide (BPO) in non-aque-ous media (acetonitrile and tetrachloromethane), was investigated with a quantitative UV-spectrophotometrical approach. Progress of the above reaction was controlled by selected kinetic parameters: the apparent Michaelis constant (Kmapp), the specific rate constant (Ksp), the activation energy (Ea), the maximum reaction rate (Vmax), and the Arrhenius’ pre-exponential factor (Z0). Conclusions on the tentative mechanism of the catalytic process observed were drawn from the calculated values of the Gibbs energy of activation (ΔG*), the enthalpy of activation (ΔH*), and entropy of activation (ΔS*)

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He, Kaihua, Yanzhi Yang, Zhengyi Zhao, Zhiyong Yan, and Xuechun Xiao. "One-Step Synthesis AlCo2O4 and Derived “Al” to Double Optimise the Thermal Decomposition Kinetics and Enthalpy of Ammonium Perchlorate." Colloids and Interfaces 9, no. 3 (2025): 28. https://doi.org/10.3390/colloids9030028.

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The solution combustion method is widely used because of its simple operation and ability to produce porous structures. The chemical composition and morphological structure of the material can be regulated by different oxidiser-to-fuel ratios (φ). In this work, AlCo2O4 derived “Al” catalytic materials were successfully synthesised by adjusting the fuel-to-oxidiser ratio using a one-step solution combustion method. On the one hand, the aluminium nanoparticles act as a part of the metal fuel in the composite solid propellant and, at the same time, serve as a catalytic material. In contrast, the thermal decomposition performance of AP was significantly improved by the synergistic catalysis of AlCo2O4. Among the samples prepared under different fuel ratios, considering all aspects (high-temperature decomposition temperature, activation energy, and decomposition heat) comprehensively, the AlCo2O4 prepared with φ = 0.5 had a more excellent catalytic effect on AP thermal decomposition, and the THTD of AP was reduced to 285.4 °C, which is 188.08 °C lower. The activation energy of the thermal decomposition of AP was also significantly reduced (from 296.14 kJ/mol to 211.67 kJ/mol). In addition, the ignition delay time of AlCo2O4-AP/HTPB was drastically shortened to 9 ms from 28 ms after the addition of 7% AlCo2O4 derived “Al” catalytic materials. Composite solid propellants have shown great potential for application.

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Wen, Pu Hong. "Kinetic Investigation of Thermal Decomposition Reactions of Podophyllic Acid and Picropodophyllic Acid." Advanced Materials Research 391-392 (December 2011): 1230–34. http://dx.doi.org/10.4028/www.scientific.net/amr.391-392.1230.

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The thermal behavior and thermal decomposition kinetic parameters of podophyllic acid and picropodophyllic acid in a temperature-programmed mode have been investigated by means of DSC and TG-DTG. The kinetic model functions in differential and integral forms of the thermal decomposition reactions mentioned above for leading stage were established. The kinetic parameters of the apparent activation energy Ea and per-exponential factor A were obtained from analysis of the TG-DTG curves by integral and differential methods. The most probable kinetic model function of the decomposition reaction in differential form was 2/3•α-1/2 for podophyllic acid and 1/2• (1-α)-1 for picropodophyllic acid. The values of Ea indicated that the reactivity of picropodophyllic acid was highter than that of podophyllic acid in the thermal decomposition reaction. The values of the entropy of activation ΔS≠, enthalpy of activation ΔH≠ and free energy of activation ΔG≠ of the reactions were estimated.

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Hu, Mengzhu, Bin Tang, Qinqin Liang, et al. "Research on Thermal Aging Behavior and Thermal Decomposition of Insulating Material XLPE." Advances in Engineering Technology Research 1, no. 2 (2022): 23. http://dx.doi.org/10.56028/aetr.1.2.23.

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In this paper, accelerated thermal aging experiment was used to simulate the thermal aging behavior of XLPE, and FT-IR, DSC, TG and other test techniques were used to characterize the materials with different aging periods. The results show that with the aging time, the oxygen-containing groups in XLPE increase, and the crosslinking degree of molecular chains decreases. At the same time, the melting peak of the endothermic peak of the material shifts and the endothermic enthalpy decreases. After aging, the high temperature resistance of XLPE decreases and decomposition occurs more easily. The thermal decomposition of XLPE before and after thermal aging was carried out at different temperatures, and the corresponding thermal decomposition gases were collected. According to GC-MS analysis, the thermal decomposition gas products were all small molecule unsaturated olefin, small molecule containing oxygen and long carbon chain containing oxygen, and the content changed significantly before and after aging.

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Hu, Mengzhu, Bin Tang, Qinqin Liang, et al. "Research on Thermal Aging Behavior and Thermal Decomposition of Insulating Material XLPE." Advances in Engineering Technology Research 2, no. 1 (2022): 23. http://dx.doi.org/10.56028/aetr.2.1.23.

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In this paper, accelerated thermal aging experiment was used to simulate the thermal aging behavior of XLPE, and FT-IR, DSC, TG and other test techniques were used to characterize the materials with different aging periods. The results show that with the aging time, the oxygen-containing groups in XLPE increase, and the crosslinking degree of molecular chains decreases. At the same time, the melting peak of the endothermic peak of the material shifts and the endothermic enthalpy decreases. After aging, the high temperature resistance of XLPE decreases and decomposition occurs more easily. The thermal decomposition of XLPE before and after thermal aging was carried out at different temperatures, and the corresponding thermal decomposition gases were collected. According to GC-MS analysis, the thermal decomposition gas products were all small molecule unsaturated olefin, small molecule containing oxygen and long carbon chain containing oxygen, and the content changed significantly before and after aging.

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Chen, Jinqiang, and Simona Bordoni. "Orographic Effects of the Tibetan Plateau on the East Asian Summer Monsoon: An Energetic Perspective." Journal of Climate 27, no. 8 (2014): 3052–72. http://dx.doi.org/10.1175/jcli-d-13-00479.1.

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Abstract This paper investigates the dynamical processes through which the Tibetan Plateau (TP) influences the East Asian summer monsoon (EASM) within the framework of the moist static energy (MSE) budget, using both observations and atmospheric general circulation model (AGCM) simulations. The focus is on the most prominent feature of the EASM, the so-called meiyu–baiu (MB), which is characterized by a well-defined, southwest–northeast elongated quasi-stationary rainfall band, spanning from eastern China to Japan and into the northwestern Pacific Ocean between mid-June and mid-July. Observational analyses of the MSE budget of the MB front indicate that horizontal advection of moist enthalpy, and primarily of dry enthalpy, sustains the front in a region of otherwise negative net energy input into the atmospheric column. A decomposition of the horizontal dry enthalpy advection into mean, transient, and stationary eddy fluxes identifies the longitudinal thermal gradient due to zonal asymmetries and the meridional stationary eddy velocity as the most influential factors determining the pattern of horizontal moist enthalpy advection. Numerical simulations in which the TP is either retained or removed show that the TP influences the stationary enthalpy flux, and hence the MB front, primarily by changing the meridional stationary eddy velocity, with reinforced southerly wind over the MB region and northerly wind to its north. Changes in the longitudinal thermal gradient are mainly confined to the near downstream of the TP, with the resulting changes in zonal warm air advection having a lesser impact on the rainfall in the extended MB region.

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Akinyi, Caroline J., and Jude O. Iroh. "Heat of Decomposition and Fire Retardant Behavior of Polyimide-Graphene Nanocomposites." Energies 14, no. 13 (2021): 3948. http://dx.doi.org/10.3390/en14133948.

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Polyimide is a high-performance engineering polymer with outstanding thermomechanical properties. Because of its inherent fire-retardant properties, polyimide nanocomposite is an excellent material for packaging electronic devices, and it is an attractive electrode material for batteries and supercapacitors. The fire-retardant behavior of polyimide can be remarkably improved when polyimide is reinforced with multilayered graphene sheets. Differential scanning calorimetry and thermogravimetric analysis were used to study the heat of decomposition and gravimetric decomposition rate, respectively, of polyimide-graphene nanocomposites. Polyimide/graphene nanocomposites containing 10, 20, 30, 40, and 50 wt.% of multilayered graphene sheets were heated at a rate of 10 and 30 °C/min in air and in nitrogen atmosphere, respectively. The rate of mass loss was found to remarkably decrease by up to 198% for nanocomposites containing 50 wt.% of graphene. The enthalpy change resulting from the decomposition of the imide ring was found to decrease by 1166% in nitrogen atmosphere, indicating the outstanding heat-shielding properties of multilayered graphene sheets due to their high thermal conductivity. Graphene sheets are believed to form a continuous carbonaceous char layer that protects the imide ring against decomposition, hence decreasing initial mass loss. The enthalpy changes due to combustion, obtained from differential scanning calorimetry, were used to calculate the theoretical heat release rates, a major parameter in the determination of flammability of polymers. The heat release rate decreased by 62% for composites containing 10 wt.% of graphene compared to the neat polyimide matrix. Polyimide has a relatively lower heat of combustion as compared with graphene. However, graphene significantly decreases the mass loss rates of polyimide. The combined interaction of graphene and polyimide led to an overall decrease in the heat release rate. It is noted that both mass loss rate and heat of combustion are important factors that contribute to the rate of heat released.

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Song, Jin Hong, Zhi Ming Zhou, and Shu Bo Wang. "Bis (2,2-Dinitroethyl-N-Nitro)Ethylenediamine-Based Energetic Salts and their Thermolysis Studies." Advanced Materials Research 781-784 (September 2013): 2458–62. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.2458.

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New energetic bis (2,2-dinitroethyl-N-nitro) ethylenediamine-based salts exhibiting reasonable physical properties, good detonation properties and relatively low impact sensitivities were synthesized in high yield by direct neutralization reactions. The thermal decomposition behavior of two new bis (2,2-dinitroethyl-N-nitro) ethylenediamine-based energetic salts was firstly measured using differential scanning calorimetry (DSC) at six different heating rates. The thermal decomposition kinetics and several thermodynamic parameters of the salts, such as apparent activation energy (E), pre-exponential factor (A), extrapolated onset temperature (T0), activation entropy (∆S≠), activation enthalpy (∆H≠), activation Gibbs free energy (∆G≠), critical temperature of thermal explosion (Tb) and the Arrhenius equations were obtained under non-isothermal conditions by DSC.

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Li, JunYang, Ming Yu, Dong Sun, PengXin Liu, and XianXu Yuan. "Wall heat transfer in high-enthalpy hypersonic turbulent boundary layers." Physics of Fluids 34, no. 8 (2022): 085102. http://dx.doi.org/10.1063/5.0100416.

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In this paper, we investigate the differences in wall heat transfer between the low- and high-enthalpy turbulent boundary layers by exploiting direct numerical simulation databases of hypersonic turbulent boundary layers at the free-stream Mach number of 4.5 and the friction Reynolds number of 800. For that purpose, we refine the integral formula of decomposing the wall heat flux proposed by Sun et al. [“A decomposition formula for the wall heat flux of a compressible boundary layer,” Adv. Aerodyn. 4, 1–13 (2022)], enabling us to scrutinize the contribution of different physical processes. Statistical results show that the mean wall heat transfer is primarily contributed by the heat conduction, the turbulent heat transfer, viscous dissipation of mean kinetic energy, and turbulent kinetic energy production. Among these processes, the contribution of the turbulent heat flux in the high-enthalpy case is 10% higher than that in the low-enthalpy case. Such discrepancy is caused by the turbulent–chemistry interaction consisting of velocity and species mass fraction fluctuations. Coherent structures in the conditionally averaged fields related to this process reveal that the sweep in the viscous sublayer and ejection in the logarithmic layer bringing the hot fluid downward and upward, respectively, significantly alter the distribution of the species mass fraction. The wall heat flux fluctuations are slightly enhanced in the high-enthalpy flows, which is ascribed to be the intensification of traveling wave packets.

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Naufal, F. D., E. T. Lasiman, A. Z. F. Syafira, et al. "DFT study on gas-phase decomposition of ethylene carbonate in the presence of LiPF₆, LiBF₄, PF₆ ^-, and BF₄ ^-." Journal of Physics: Conference Series 2243, no. 1 (2022): 012109. http://dx.doi.org/10.1088/1742-6596/2243/1/012109.

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Abstract The decomposition of Li-ion battery (LIB) electrolyte has been a well-known challenge that needs to be overcome. The most common electrolyte on lithium-ion batteries is LiPF6 which has all-balanced properties, while LiBF4 has been proven for its superior stability. These lithium salts are often dissolved in Ethylene Carbonate (EC) to form liquid electrolyte systems. In this work, we investigate the decomposition mechanism of EC in the presence of LiPF6, LiBF4, and their delithiated counterpart by means of first-principles density functional theory (DFT) calculations. We found that the energy barrier of decomposition on LiBF4 presence is 0.42 eV lower than on LiPF6 presence, also on BF4 - presence is 0.22 eV lower than PF6 - presence. This suggests that LiBF4 and BF4 - presence reduces EC stability more than LiPF6 and PF6 - anion. Moreover, the presence of Li+ ion increases the energy barrier of decomposition (about 0.79 eV on PF6 - case, 0.59 eV on BF4 - case) but decreases enthalpy change significantly (about 1.58 eV on PF6 - case, 1.43 eV on BF4 - case). This suggests that while the Li+ ion causes the decomposition to be slower, its presence destabilizes the EC more.

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KISHOR, ARORA. "Thermal Decomposition Kinetics of Thorium(IV) and Dioxouranium(VI) Complexes." Journal of Indian Chemical Society Vol. 74, Aug 1997 (1997): 589–96. https://doi.org/10.5281/zenodo.5890705.

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Department of Chemistry, Government Post-Graduate College, Morena-476 001 Thermal decomposition kinetics studies of thermal reactions are useful in studying parameters like free energy change (ΔG*), enthalpy change (ΔH*), activation energy (E*) and ultimately the entropy change (ΔS*) and pre-exponential factor (A) or frequency factor (Z). This concept was f"u-st proposed somewhere In 1928. Since then so many methods and equations have been put forward for studying thermal decomposition kinetics of the reaction Present report discusses some aspects of non-isothermal kinetic studies of some thorium(IV) and dioxouranium(VI) complexes with various pyrazolones, amine N-oxides and aromatic Schlff bases.

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Dong, Haibo, Haonan Chu, Yunhao Liu, Shicheng Liu, Wenyu Ye, and Jiaming Yan. "Insights into the Pyrolysis Properties of Environmentally Friendly PMVE/N2 Gas Mixtures: A Collaborative Analysis Based on Density Functional Theory and Reaction Kinetics." Applied Sciences 15, no. 10 (2025): 5272. https://doi.org/10.3390/app15105272.

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With growing environmental concerns, the search for alternative gases to replace SF6 has become a key focus in the power industry. Perfluoromethyl vinyl ether (PMVE), with its low global warming potential (GWP) and excellent insulation properties, is a promising candidate. When mixed with N2, PMVE not only decreases the liquefaction temperature but also enhances insulation performance, making the gas mixture more suitable for engineering applications. In this study, reactive molecular dynamics (ReaxFF-MD) and density functional theory (DFT) calculations were combined to investigate the influence of temperature on the decomposition characteristics of a PMVE/N2 mixture. The reaction pathways and reaction enthalpy of PMVE and its major decomposition products were analyzed in detail. The results showed that, as temperature increases, the decomposition intensity of PMVE is enhanced, leading to a higher reaction rate and accelerated formation of decomposition products. Moreover, the main decomposition products of the PMVE/N2 mixture include C, C2F2, CF2, CN, CO, CF2O, F, O, and other small molecules and free radicals. The dynamic balance between the generated free radicals helps maintain the system’s insulation capacity. However, toxic decomposition byproducts such as CF2O, C2N2, and CO were also detected. This study provides valuable insights into the engineering applications of PMVE/N2 mixtures.

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Gudosi, Kalagouda, Prabhugouda Maravalli, and Timmanagouda Goudar. "Thermo-kinetic and spectral studies of niobium(V) complexes with 3-substituted-4-amino-5-mercapto-1, 2, 4-triazole Schiff bases." Journal of the Serbian Chemical Society 70, no. 4 (2005): 643–50. http://dx.doi.org/10.2298/jsc0504643g.

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Metal complexes of niobium(V) with 3-substituted-4-amino-5-mercapto 1,2,4-triazole Schiff bases have been synthesized in dry chloroform under a nitrogen atmosphere. They were characterized by elemental analysis, molar conductance, electronic, infrared, 1H-NMR spectroscopy and thermal studies. Parameters, such as energy of activation (Ea), enthalpy (?H#), entropy (?S#) and Gibbs energy (?G#), were computed from the thermal decomposition data. Based on the spectral and thermal studies, a coordination number of seven is proposed.

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Wen, Pu Hong. "Kinetic Investigation of Thermal Decomposition Reaction of Ethane-1,2-Diamine Copper(II) Chloride, C₂H₈N₂CuCl₂." Applied Mechanics and Materials 665 (October 2014): 255–59. http://dx.doi.org/10.4028/www.scientific.net/amm.665.255.

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:The thermal behavior and thermal decomposition kinetic parameters of ethane-1,2-diamine copper (II) chloride (EDCC) in a temperature-programmed mode have been investigated by mean of TG-DTG. There are four stages in the thermal decomposition process. The kinetic parameters of the apparent activation energyEa(130.2, 143.6 and 158.9 KJ·mol–1) and per-exponential factorA(1011.80, 1012.18and 1011.83s–1) in II, III and IV stages were obtained from analysis of the TG-DTG curves by Kissinger method. The values ofEaindicated that the difficulty coefficient of pyrolysis in II, III and IV stages was increased in the order: II < III < IV. The values of the entropy of activation ΔS≠, enthalpy of activation ΔH≠and free energy of activation ΔG≠of the reaction were estimated.

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Mallick, Subhasish, and Pradeep Kumar. "Switching of the reaction enthalpy from exothermic to endothermic for decomposition of H2CO3 under confinement." Physical Chemistry Chemical Physics 21, no. 37 (2019): 20849–56. http://dx.doi.org/10.1039/c9cp04587b.

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Various size fullerenes (C60, C70 and C84) have been used as a means of confinement to study the decomposition reaction of carbonic acid alone as well as in the presence of a single water molecule in a confined environment.

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Memon, Abid A., Saqib Murtaza, M. Asif Memon, Kaleemullah Bhatti, Mojammel Haque, and Mohamed R. Ali. "Simulation of Thermal Decomposition of Calcium Oxide in Water with Different Activation Energy and the High Reynolds Number." Complexity 2022 (August 26, 2022): 1–21. http://dx.doi.org/10.1155/2022/3877475.

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In this article, we are going to suggest the parameters to control the thermal decomposition in a reactor that is continuously providing a cooling environment inside the tube. For this purpose, 5 governing partial differential equations gained through mass, momentum, and energy balance laws and one ordinary differential equation are used to simulate this chemical reaction with finite element package COMSOL Multiphysics 5.6. In the simulation, the thermal decomposition of calcium oxide in the water is controlled with the use of Reynolds numbers ranging from 100 to 1000, activation energy from 75,000 j/mol to 80,000 j/mol, and an initial concentration of 1% to 5%. The results are presented through the graphs and tables for conversion profile, temperature distribution, enthalpy change, diffusivity, the heat source of reaction, and Sherwood and Lewis number along the axial length of the reactor. Specifically, it was found a low-speed profile at the inlet will give a 100% conversion at Re = 100 for 3% to 5% of the initial concentration. The maximum temperature and enthalpy change in the reactor are decreasing increase in the Reynolds number. Also, the decrement of the Sherwood number along the length showed that the mass diffusion is always dominant over convection-diffusion for all cases of parameters. The validation is made by comparing the numerical results with the experimental correlations.

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Hongbo, Tang, Li Yanping, Zhang Wen, and Dong Siqing. "Synthesis, Optimization, Property, Characterization, and Application of Dialdehyde Cross-Linking Guar Gum." International Journal of Polymer Science 2016 (2016): 1–14. http://dx.doi.org/10.1155/2016/6482461.

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Dialdehyde cross-linking guar gum (DCLGG), as a novel material, was synthesized using phosphorus oxychloride as a cross-linking reagent, sodium periodate as an oxidant, and ethanol as a solvent through keeping the original particle form of guar gum. The process parameters such as the reaction temperature, reaction time, pH, amount of sodium periodate, and amount of ethanol were optimized by the response surface methodology in order to obtain the regression model of the oxidization. The covalent binding of L-asparagine onto the surfaces of DCLGG was further investigated. The results showed that the best technological conditions for preparing DCLGG were as follows: reaction temperature = 40°C, reaction time = 3.0 h, pH = 4.0, and amount of ethanol = 74.5%. The swelling power of DCLGG was intermediate between cross-linking guar gum and dialdehyde guar gum. The cross-linking and dialdehyde oxidization reduced the viscosity of GG. The cross-liking reduced the melting enthalpy of GG. However, the oxidization increased melting enthalpy of ACLGG. The thermal stability of GG was increased by cross-linking or oxidization. The variation of the onset decomposition temperature and end decomposition temperature of GG was not consistent with thermal stability of GG. L-asparagine could be chemically bound well by DCLGG through forming Schiff base under the weak acidity. The maximum adsorption capacity of L-asparagine on DCLGG with aldehyde content of 56.2% reached 21.9 mg/g.

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Xue-ying, Wu, Wang Ya-zhen, Di Yu-tao, Lan Tian-yu, and Zu Li-wu. "Preparation and Thermal Decomposition Kinetics of Novel Silane Coupling Agent with Mercapto Group." Journal of Nanomaterials 2019 (December 18, 2019): 1–9. http://dx.doi.org/10.1155/2019/6089065.

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Using carbon disulfide and 3-aminopropyltriethoxysilane as raw materials, a novel silane coupling agent with a terminal group was synthesized for the first time. The compound was synthesized in two steps in ethanol water solvent under the action of the catalyst triethylamine and a sulfhydryl-protecting agent. The product was characterized by FT-IR, 1H NMR, and mass spectra to determine and prove its structure. The best experimental scheme was explored by a single factor experiment: a thiol-protecting agent selected iodomethane, the total reaction time was 2 hours, the two-step reaction temperature was 15°C and 10°C, respectively, and ncarbon disulfide: n3−aminopropyl three ethoxysilane=1.4:1. Under these conditions, the product yield was up to 74.28%. Secondly, using the nonisothermal decomposition method, the thermal stability and thermal decomposition enthalpy of a thiohydrazide-iminopropyltriethoxysilane coupling agent were measured by a differential scanning calorimeter (DSC). Thereby, the thermal decomposition kinetic parameters and kinetic equations of the thiohydrazide-iminopropyltriethoxysilane coupling agent were derived.

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M., B. Reguera, Galante N., Varela N., et al. "Kinetics and Mechanism of Thermal Decomposition of Malonaldehyde Peroxide (DPM) in Solution." Chemistry Research Journal 6, no. 6 (2021): 20–25. https://doi.org/10.5281/zenodo.12087639.

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Abstract In this paper, the kinetics of the thermal decomposition reaction of 3,6-diethanal-1,2,4,5 tetroxane (malonaldehydeperoxide, DPM) is investigated in methanol solvents at different temperatures. In the temperature range of 130.0-166.0 ° C studied and at the concentration of 2 x 10-2 M, it follows a first order kinetic law up to at least 60% DPM conversion. The organic products observed were malonaldehyde. A stepwise mechanism of decomposition was proposed where the first step is the homolytic unimolecular rupture of the O-O bond. The activation enthalpy and activation entropy for DPM in methanol were calculated (ΔH0# = 86.1 ± 2.7 kJ mol-1 y ΔS0# = -65.2 ± 6.0 J mol-1 K-1)

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M., B. Reguera, Galante N., Varela N., et al. "Kinetics and Mechanism of Thermal Decomposition of Malonaldehyde Peroxide (DPM) in Solution." Chemistry Research Journal 6, no. 6 (2021): 20–25. https://doi.org/10.5281/zenodo.11894353.

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Abstract In this paper, the kinetics of the thermal decomposition reaction of 3,6-diethanal-1,2,4,5 tetroxane (malonaldehydeperoxide, DPM) is investigated in methanol solvents at different temperatures. In the temperature range of 130.0-166.0 ° C studied and at the concentration of 2 x 10-2 M, it follows a first order kinetic law up to at least 60% DPM conversion. The organic products observed were malonaldehyde. A stepwise mechanism of decomposition was proposed where the first step is the homolytic unimolecular rupture of the O-O bond. The activation enthalpy and activation entropy for DPM in methanol were calculated (ΔH0# = 86.1 ± 2.7 kJ mol-1 y ΔS0# = -65.2 ± 6.0 J mol-1 K-1)

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48

Boukeciat, Hani, Ahmed Fouzi Tarchoun, Djalal Trache, et al. "Towards Investigating the Effect of Ammonium Nitrate on the Characteristics and Thermal Decomposition Behavior of Energetic Double Base NC/DEGDN Composite." Materials 15, no. 22 (2022): 8138. http://dx.doi.org/10.3390/ma15228138.

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This research work aimed to elaborate on a new modified double-base propellant containing nitrocellulose (NC), ammonium nitrate (AN), and diethylene glycol dinitrate (DEGDN). The developed AN/NC-DEGDN formulation was successfully obtained through a casting process and fully characterized in terms of its chemical structure, morphological features, and thermal behavior. Beforehand, theoretical calculation by the CEA-NASA program was applied to select the optimal composition of the formulation. Experimental findings demonstrated the homogenous dispersion of AN oxidizer in the NC-DEGDN matrix without alteration of their molecular structures. The catalytic influence of AN on the thermal decomposition behavior of NC-DEGDN film was also elucidated by thermal analyses. When AN was incorporated into the formulation, the decomposition peak temperatures for the different decomposition processes were shifted toward lower temperatures, while the total enthalpy of decomposition increased by around 1272.24 J/g. In addition, the kinetics of the thermal decomposition of the developed modified double base propellant were investigated using DSC results coupled with model kinetic approaches. It was found that the addition of AN decreases the activation energy of nitrate esters from 134.5 kJ/mol to 118.84 kJ/mol, providing evidence for its excellent catalytic effect. Overall, this investigation could serve as a reference for developing future generation of modified double-base propellants.

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Tsioptsias, C. "Thermodynamic explanation and criterion for the exhibition of melting inability in molecular species." AIMS Materials Science 10, no. 4 (2023): 618–36. http://dx.doi.org/10.3934/matersci.2023035.

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<abstract> Thermodynamic properties of matter e.g., melting point, are important for various applications. However, in some substances the primary observed effect upon heating is decomposition which in some cases is accompanied by fluidization. Thus, it would be very useful to be able to predict if a given substance will be able to melt or will exhibit melting inability upon heating. In this work, a thermodynamic explanation for the melting inability of molecular solids is provided and a corresponding criterion is proposed for the prediction of melting ability or inability of a given substance. One key concept is to study the strength of the weakest chemical bond rather than overall enthalpy of reaction. This arises from the fact that if decomposition occurs, then, regardless of the extent of decomposition, the transition cannot be considered to be melting. The criterion can be combined with sophisticated modeling in order to derive accurate values. Here, a simple method is proposed and an approximate index is developed which allows for a rapid and massive implementation of the criterion. The index is based on the concept of group contributions methods (estimation of the enthalpy of the maximum possible interactions, ${\mathit{\Delta}} H_{max }$) and on a distorted version of Trouton's rule (correlation of $ {\mathit{\Delta}} H_{max }$ with the heat required for melting). The correlation factor (${x}_{melting}$) was found to be equal to 40.6%. The index is successfully applied in various organic substances, including (bio)molecules of pharmaceutical/nutraceutical interest. Index values between −30 and 0 correspond to marginal cases of rather high uncertainty. Positive index values clearly point out melting inability. The proposed index successfully predicts the melting ability/inability in more than 80% of the studied substances. </abstract>

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Ashraf, Ahmed, Ahmed Fahd, Hosam E. Mostafa, E. M. Yossef, and Sherif Elbasuney. "The potentials of copper chromite nanoparticles on ammonium nitrate decomposition: Towards eco-friendly oxidizers for green solid propellants." Journal of Physics: Conference Series 2830, no. 1 (2024): 012013. http://dx.doi.org/10.1088/1742-6596/2830/1/012013.

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Abstract Ammonium perchlorate (AP) is the universal oxidizer for solid propellants; AP combustion is accompanied with the release of white smoke (HCl). HCl has raised an environmental concern; it could cause acidic rain and deteriorate the fertile soil. Chlorine free and eco-friendly oxidizers are highly appreciated for green solid propellants. Ammonium nitrate (AN) could be the greener substitute for AP; yet AN expose low performance. Whereas AP demonstrated exothermic decomposition with the release of -733 J/g; AN demonstrated strong endothermic decomposition process of +1707 J/g. AN with strong endothermic decomposition process could render high burning rates. Copper chromite Nano catalyst of 45 nm was developed via hydrothermal synthesis. Copper chromite was integrated into AN matrix. Catalyzed AN demonstrated advanced exothermic decomposition enthalpy of -1492 J/g. Catalysed AN experienced diminish in activation energy by - 41.5 %, and – 40.6 % using Kissinger and Ozawa models respectively. Copper chromite NPs could secure novel catalytic effect via condensed phase reactions of chromium, and copper ions with nitrate ions (NO-3) to develop NOx gases. This catalytic effect can secure alternative pathway with low energy barrier. Consequently, catalysed AN can expose novel characteristics as a green eco-friendly oxidizer.

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Journal articles on the topic 'Enthalpy decomposition'

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