scholarly journals Thermal Decomposition of HMX: Low Temperature Reaction Kinetics and their Use for Assessing Response in Abnormal Thermal Environments and Implications for Long-Term Aging

1995 ◽  
Vol 418 ◽  
Author(s):  
Richard Behrens ◽  
Suryanarayana Bulusu
Keyword(s):  
Thermal Decomposition ◽  
Solid Phase ◽  
Test Sample ◽  
Storage Conditions ◽  
Kcal Mole ◽  
Decomposition Products ◽  
Gaseous Products ◽  
Thermal Environments ◽  
Higher Temperature

AbstractThe thermal decomposition of HMX between 175°C and 200°C has been studied using the simultaneous thermogravimetric modulated beam mass spectrometer (STMBMS) apparatus with a focus on the initial stages of the decomposition. The identity of thermal decomposition products is the same as that measured in previous higher temperature experiments. The initial stages of the decomposition are characterized by an induction period followed by two acceleratory periods. The Arrhenius parameters for the induction and two acceleratory periods are (Log(A)= 18.2 ± 0.8, Ea = 48.2 ± 1.8 kcal/mole), (Log (A) = 17.15 ± 1.5 and Ea = 48.9 ± 3.2 kcal/mole), (Log (A) = 19.1 ± 3.0 and Ea = 52.1 ± 6.3 kcal/mole), respectively. The data can be used to calculate the time and temperature required to decompose a desired fraction of a test sample that is being prepared to test the effect of thermal degradation on its sensitivity or burn rates. It can also be used to estimate the extent of decomposition that may be expected under normal storage conditions for munitions containing HMX. The data, along with previous mechanistic studies conducted at higher temperatures, suggest that the process that controls the early stages of decomposition of HMX in the solid phase is scission of the N-NO2 bond, reaction of the NO2 within a “lattice cage” to form the mononitroso analogue of HMX and decomposition of the mononitroso HMX within the HMX lattice to form gaseous products that are retained in bubbles or diffuse into the surrounding lattice.

Effect on Cs removal of solid-phase metal oxidation in metal ferrocyanides

2017 ◽  
Vol 105 (12) ◽  
Author(s):  
Keun-Young Lee ◽  
Jimin Kim ◽  
Maengkyo Oh ◽  
Eil-Hee Lee ◽  
Kwang-Wook Kim ◽  
...  
Keyword(s):  
Treatment Process ◽  
Solid Phase ◽  
Storage Conditions ◽  
Radioactive Cesium ◽  
Metal Oxidation ◽  
Aging Period ◽  
Higher Temperature ◽  
Increasing Temperature ◽  
And Storage ◽  
Cobalt And Nickel

AbstractMetal ferrocyanides (MFCs) have been studied for many years and are regarded as efficient adsorbents for the selective removal of radioactive cesium (Cs) from contaminated aqueous solutions. Although their efficiency has been demonstrated, various investigations on the physicochemical, thermal, and radiological stability of the solids of MFCs are required to enhance the applicability of MFCs in the treatment process. We observed that the Cs adsorption efficiencies of cobalt and nickel ferrocyanides decreased as their aging period increased, while the Cs adsorption efficiencies of copper and zinc ferrocyanides did not decrease. The tendencies of these ferrocyanides were accelerated by exposure of the solids at a higher temperature for a longer time. Our comprehensive analyses demonstrated that only the oxidizable metals in the MFCs can be oxidized by aging time and increasing temperature; also, this affects the Cs removal efficiency by decreasing the exchangeable sites in the solids. The chemical stability of MFCs is very important for the optimization of the synthesis and storage conditions.

The thermal decomposition of RDX at temperatures below the melting point. II. Activation energy

1970 ◽  
Vol 23 (4) ◽  
pp. 749 ◽  
Author(s):  
JJ Batten ◽  
DC Murdie
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Melting Point ◽  
Kinetic Parameter ◽  
Arrhenius Equation ◽  
Kcal Mole ◽  
Decomposition Products ◽  
Sample Geometry ◽  
Temperature Range ◽  
Definition Of

The activation energy has been determined in the temperature range 170-198�. If the sample was spread the activation energy was independent of the definition of the kinetic parameter substituted in the Arrhenius equation and was 63 kcal mole-1. In the case of the unspread samples the activation energies of the induction, acceleration, and maximum rates were 49, 43, and 62 kcal mole-1 respectively. The effect that sample geometry has on the activation energy is attributed to gaseous decomposition products influencing the reaction.

The thermal decomposition of ammonium perchlorate - І. Introduction, experimental, analysis of gaseous products, and thermal decomposition experiments

1954 ◽  
Vol 227 (1168) ◽  
pp. 115-132 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Ammonium Perchlorate ◽  
Vapour Phase ◽  
Gas Analysis ◽  
Metallic Oxide ◽  
Decomposition Products ◽  
Gaseous Products ◽  
Crystal Transformation ◽  
Temperature Ranges ◽  
Decomposition Experiments

The thermal decomposition of ammonium perchlorate in vacuo and under small initial pressures of nitrogen, to suppress sublimation, has been investigated in the temperature ranges 220 to 280°C and 380 to 450°C. The experimental techniques for following the decomposition and subsequent analysis of the products are described and gas analysis results given. In the low -temperature range only 30% decomposition occurred though the ‘residue’ was still ammonium perchlorate. In vacuo sublimation occurred all the time and also after decomposition had ceased which indicated that the reaction was not in the vapour phase. Some of the properties of the sublimed material and the ‘residue’ were investigated; in particular, it was found that the residue which was porous in texture (the decomposition had occurred throughout the crystal) could be ‘rejuvenated’ by exposure to a solvent vapour. The crystal transformation at 240°C from orthorhombic to cubic, the addition of impurities which might be intermediate decomposition products, and the addition of some metallic oxide catalysts, were also investigated.

scholarly journals Solid-Phase Thermal Decomposition of 2,4-Dinitroimidazole (2,4-DNI)

1995 ◽  
Vol 418 ◽  
Author(s):  
Leanna Minier ◽  
Richard Behrens ◽  
Suryanarayana Bulusu
Keyword(s):  
Thermal Decomposition ◽  
Induction Period ◽  
Solid Phase ◽  
Low Molecular Weight ◽  
Ftir Analysis ◽  
Pyrolysis Products ◽  
Gaseous Products ◽  
Elemental Formula ◽  
Gas Formation ◽  
Primary Products

AbstractThe solid-phase thermal decomposition of the insensitive energetic aromatic heterocycle 2,4- dinitroimidazole (2,4-DNI: mp 265–274°C) is studied utilizing simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) between 200° and 247°C. The pyrolysis products have been identified using perdeuterated and N-labeled isotopomers. The products consist of low molecular-weight gases and a thermally stable solid residue. The major gaseous products are NO, CO2, CO, N2, HNCO and H2O. Minor gaseous products are HCN, C2N2, NO2, C3H4N2, C3H3N3O and NH3. The elemental formula of the residue is C2HN2O and FTIR analysis suggests that it is polyurea- and polycarbamate-like in nature. The rates of formation of the gaseous products and their respective quantities have been determined for a typical isothermal decomposition experiment at 235°C. The temporal behaviors of the gas formation rates indicate that the overall decomposition is characterized by a sequence of four events; 1) an early decomposition period induced by impurities and H2O, 2) an induction period where CO2 and NO are the primary products formed at relatively constant rates, 3) an autoacceleratory period that peaks when the sample is depleted and 4) a final period in which the residue decomposes. Arrhenius parameters for the induction period are Ea = 46.9 ± 0.7 kcal/mol and Log(A) = 16.3 ± 0.3. Decomposition pathways that are consistent with the data are presented.

scholarly journals Synthesis, Polymorphism and Thermal Decomposition Process of (n-C4H9)4NRE(BH4)4 for RE = Ho, Tm and Yb

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1329
Author(s):  
Wojciech Wegner ◽  
Tomasz Jaroń
Keyword(s):  
Thermal Decomposition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Decomposition Products ◽  
Gaseous Products ◽  
Dsc Measurements ◽  
Unit Cells ◽  
Polymorphic Forms ◽  
Solid Decomposition ◽  
Derivatives Of

In total, three novel organic derivatives of lanthanide borohydrides, n-But4NRE(BH4)4 (TBAREB), RE = Ho, Tm, Yb, have been prepared utilizing mechanochemical synthesis and purified via solvent extraction. Studies by single crystal and powder X-ray diffraction (SC-XRD and PXRD) revealed that they crystalize in two polymorphic forms, α- and β-TBAREB, adopting monoclinic (P21/c) and orthorhombic (Pnna) unit cells, previously found in TBAYB and TBAScB, respectively. Thermal decomposition of these compounds has been investigated using thermogravimetric analysis and differential scanning calorimetry (TGA/DSC) measurements, along with the analysis of the gaseous products with mass spectrometry (MS) and with analysis of the solid decomposition products with PXRD. TBAHoB and TBAYbB melt around 75 °C, which renders them new ionic liquids with relatively low melting points among borohydrides.

CHARACTERISTICS OF NORSODYNE AS PLASTINATION AGENT

2019 ◽  
Vol 17 (Suppl. 2) ◽  
pp. 4-6
Author(s):  
A. Georgieva ◽  
J. Stoyanov ◽  
N. Tsandev ◽  
D. Sivrev
Keyword(s):  
Storage Temperature ◽  
Unsaturated Polyester ◽  
Specific Weight ◽  
Storage Conditions ◽  
Test Method ◽  
Test Results ◽  
Long Term Storage ◽  
New Material ◽  
Higher Temperature

Background: Norsodyne is a new material for conservation and durable preservation of biological objects. The form we use is H 13212 TAE (Polynt Composites USA, Inc., Bergamo, Italy). This is an unsaturated polyester resin in styrene that is of low styrene emission. Features: resin has a specific weight 1.10 g/cm2 at 20°C. Using test method MT-CUT23V the manufacturer has established that Brookfield viscosity at 23°C is 450-650 mPa.s. The jelly starts in 14-18 minutes and reaches its peak in 27-37 minutes at 23°C too. Acording to the test results of ISO 527 (2012) tensile strength of Norsodyne is 57 MPa and flexural strength is 98 MPa (ISO 178 (2011). Conclusion: This characteristic of Norsodyne indicates that the material can be used for the preservation and long-term storage of anatomical preparations for the needs of anatomy training. However, the Norsodyne needs special storage conditions. The material should be stored in a dark place. According to the manufacturer shelf life at 23°C in the dark is six months then spontaneous rubbing begins. The manufacturer's recommendations are: Store in the shade, out of direct sunlight. Keep storage temperature below 25°C. Unseal container just before use. Shelflife will be reduced reaching higher temperature.

An improved granular formulation for a mycoherbicidal strain ofFusarium oxysporum

Weed Science ◽  
1999 ◽  
Vol 47 (4) ◽  
pp. 473-478 ◽  
Author(s):  
K. P. Hebbar ◽  
B. A. Bailey ◽  
S. M. Poch ◽  
J. A. Lewis ◽  
R. D. Lumsden
Keyword(s):  
Shelf Life ◽  
Room Temperature ◽  
Rice Flour ◽  
Storage Conditions ◽  
Vascular Wilt ◽  
Term Survival ◽  
Chlamydospore Formation ◽  
Oil Formulation ◽  
Higher Temperature

Modifications were investigated to improve shelf-life or long-term survival upon storage of an extrudedOryza sativaL. (rice) flour : gluten : clay: oil formulation (C7) of a mycoherbicide,Fusarium oxysporumSchlechtend: Fr. f. sp.erythroxylistrain EN4, that causes vascular wilt inErythroxylum cocavar.coca(coca). Fermentor-produced biomass, which contained abundant desiccation-resistant chlamydospores, was incorporated into various adaptations of C7 and stored at room temperature (22 to 25 C) under moderately high (50 to 60%) and low (0 to 5%) relative humidities (RHs). The effect of RH on shelf-life was not significant up to 4 mo of storage, while the presence of oil, added to improve its extrusion, reduced viability significantly. Addition ofGossypium hirsutumL. (cotton) embryo flour or complete elimination of oil from the formulation improved shelf-life from 3 mo to > 12 mo. Shelf-life was further improved by removing the binding agent gluten in the formulation and replacing it with autoclavedO. sativaflour. Ability of the formulations to produce secondary propagules, tested on 1% water agar, indicated that, while adding oil had no effect,G. hirsutumembryo flour increased desiccation-resistant chlamydospore counts but lowered macroconidial counts. Autoclaved rice flour (MR) significantly improved both macroconidial and microconidial counts without affecting chlamydospore counts. None of the formulations affected the total viable propagule counts. When compared with the original formulation (C7), the modification (MRRP7), with MR,G. hirsutumembryo flour, and without oil, was found to have improved shelf-life at higher temperature and RHs and enhanced potential for secondary chlamydospore formation. These characteristics are important for survival of the formulatedF. oxysporumunder less expensive storage conditions and, once applied, for survival in the soil.

scholarly journals STUDIES ON THE PERVANADIUM COMPLEX

1961 ◽  
Vol 39 (6) ◽  
pp. 1174-1183 ◽  
Author(s):  
G. A. Dean
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Acid Solution ◽  
Anionic Complex ◽  
Cationic Complex ◽  
Kcal Mole ◽  
Decomposition Products ◽  
First Order ◽  
Discrete Variations ◽  
Kinetics Of

The 'pervanadium complex' is investigated in a general manner. The kinetics of its thermal decomposition in acid solution are shown to be first order with respect to pervanadium, the apparent activation energy is 26.5 ± 1.0 kcal/mole, and possible mechanisms are suggested. The effect of various acids upon the nature of the decomposition products is determined: almost quantitative yields of vanadium (V) or vanadium (IV) are obtained in very dilute or concentrated acid, respectively. Spectrophotometric studies indicate that in acid solution two separate complexes exist: a red (1:1) cationic complex and a yellow (1:2) anionic complex. The stoichiometry of the equilibrium between the two complexes in solutions of sulphuric acid is investigated by a method of 'discrete variations'. The equilibrium could be described by[Formula: see text]where Kr/y = 2.2 ± 0.2 at 22 °C. The anion is shown to play an important part in determining the nature of the pervanadium complex.

Solid-Phase Transformation of Cs+- and Sr2+-Bearing Zeolite Sorbents Derived From Cenospheres to Mineral-Like Forms

2009 ◽  
Vol 1193 ◽  
Author(s):  
Sergei N. Vereshchagin ◽  
Tatiana A. Vereshchagina ◽  
Leonid A. Solovyov ◽  
Nina N. Shishkina ◽  
Nataly G. Vasilieva ◽  
...  
Keyword(s):  
Solid Phase ◽  
Xrd Analysis ◽  
Multiphase System ◽  
Crystallization Peak ◽  
Strontium Content ◽  
Temperature Range ◽  
Thermochemical Transformation ◽  
Higher Temperature ◽  
Apparent Activation Energies

AbstractThe paper describes the studies of the transformation of Cs+- and Sr2+-containing zeolite sorbents synthesized from fly ash cenospheres to crystalline mineral composition, suitable for the long-term disposal. Series of Cs+- and Sr2+-exchanged NaP1-containing sorbents were subjected to the thermochemical transformation in the temperature range 40-1100°C at atmospheric pressure in air and the progress of reaction was monitored by DSC and XRD analysis. It was shown that initial sodium zeolite undergoes two-step transformation at 736-785°C and 892-982°C forming nepheline as the principle product, with the conversion temperatures being dependant on the heating rate.The thermal treatment of Cs+-bearing zeolite sorbent led to formation of a complex multiphase system, the principal components of which were nepheline and pollucite. Increasing cesium content in the samples led to a monotonous shift of crystallization peak to the higher temperature range (1005-1006°C). A more complicated behavior was observed for Sr2+-containing samples, for which the crystallization temperature tends to increase (compared with NaP1) at lower Sr contents, but it starts decreasing parallel to the Sr2+ content at Sr2+ loadings >10 mg/g. The principal crystalline phases in Sr-NaP1 sample conversion were nepheline and Sr2+-containing feldspar, the quantity of which increased parallel to the increase of strontium content in zeolite.Apparent activation energies of thermochemical transformations were calculated and possible approaches to reduce transformation temperature are discussed and experimentally illustrated.

Graphite Furnace Modification for Second Surface Atomization

1982 ◽  
Vol 36 (6) ◽  
pp. 631-636 ◽  
Author(s):  
James A. Holcombe ◽  
Michael T. Sheehan
Keyword(s):  
Thermal Decomposition ◽  
Graphite Furnace ◽  
Peak Height ◽  
Furnace Wall ◽  
Decomposition Products ◽  
Thermal Decomposition Products ◽  
Temperature Environment ◽  
The Matrix ◽  
Higher Temperature ◽  
Temperature Furnace

Preliminary results from a simple furnace modification are presented. A graphite condensation site has been located inside a commercial graphite furnace atomizer. Solution samples are deposited on the furnace wall and the analyte and other condensible species “distilled” to this site during a high temperature ash. During the atomization cycle, the analyte is revaporized from the “plug” into the higher temperature furnace environment. The plug is radiatively heated and can lag behind the wall temperature by more than 1000 K, thus providing atomization into a higher temperature environment which is more nearly isothermal. The heating program with analyte transfer permits extremely high ash temperatures to be used and offers the possibility of separating the analyte from gaseous, thermal decomposition products from the matrix. Additionally, distortions of the analytical absorbance signal caused by degradation in the pyrolytic surface of the furnace are minimized when atomization from the secondary surface is employed. Limits of detection for Ag, Cr, Cu, Fe, Pb, Sn, and Zn are within a factor of 2 of values determined using wall atomization. Studies are presented on the interference of sulfate on Sn analysis. Improved peak height sensitivity and a decreased dependency on sulfate concentrations have been observed.

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