bluuebunny/crossref_metadata_2025_split huggingface dataset:
Correlation between Gas Evolution under Vacuum or Pressure and Stability of Single‐Base Propellants
Authors: SyryczyńSki Piotr , Szmajda Jerzy 
Published: May 2005

AbstractThe processes of the gas liberation during heating single‐base propellants in vacuum or underatmospheric pressure has been studied. The results for several samples with various size of grains, water content and methods of production were compared. The results of the tests under vacuum cannot be the strict and simple measure of the stability of propellants. It is not clear whether the increase of pressure is due to the breakdown of RO‐NO2 bonds or is noly due to the evaporation of the derivatives of primary stabilizer. The amount of gas evolved depends on the size of grains, type of stabilizer, various additives etc.There are no strict boundaries between stable and unstable propellants when their decomposition rate under atmospheric pressure is measured. This method of determining the stability of single‐base propellants is useless for old samples made by unknown technology.
Effects of Partially Confined Explosion on Jet Penetration
Authors: Yadav H. S. , Bohra B. M. , Sundaram S. G. , Kulkarni M. W. 
Published: May 2005

AbstractInteraction of a metal‐explosive assembly with a normally‐incident shaped chare jet has been investigated with radiographic and oscillographic technique. Some of the significant effects associated with this interaction like detonation of explosive by impact of jet, expansion of covering metal plates, disturbance in coherence and reduction in penetration of the jet have been observed. It is found that the jet penetration in stack of mild steel plates is reduced to 30% of its blank penetration. The disturbance in the jet commences 12.3 μs after initiation of explosive and it remains for about 25 μs in the present set up.
Study of explosive and shock parameters for Compaction of Powders
Authors: Yadav H. S. , Patil B. T. , Haldar G. 
Published: May 2005

AbstractCompaction of aluminium, iron and tungsten powders of particle size 300 BSS has been studied by axisymmetrical geometry. Optimum explosive to powder mass ratio (E/M) to attain maximum density of compact has been determined for different tube diameters in each case. It has been observed that E/M ratio for smaller diameter tube is greater than that of bigger diameter tubes. Explosive and shock wave parameters like velocity of detonation and angle of conical shock wave have also been measured with sulphur coated pin oscillographic technique.
Spectroscopic Studies on Electron Donor‐Acceptor Complex between n,2,4,6‐tetranitro‐N‐methylaniline and ethylenediamine
Authors: Raha K. , Makashir P. S. , Kurian E. M. 
Published: May 2005

AbstractSpectroscopic studies indicate that N,2,4,6‐tetranitro‐N‐methylaniline (tetryl) forms two charges transfer (CT) complexes with ethylenediamine (EDA) and these complexes show absorption maxima at 440 nm and 340 nm respectively. Both the complexes have 1:1 ratio of donor to acceptor. The formation constant and molar extinction coefficient for the complexes have been determined in acetonitrile as well as in ethanol and methanol to evaluate the effect of polarity. The initial complex (λmax at 440 nm) undergoes transformation to a product complex (λmax at 340 nm) when the EDA concentration is lowered. The product complex has been isolated and characterized by IR, UV spectroscopy, thermal analysis and X‐ray diffraction (XRD). The transformation of the initially formed CT complex to the product complex in solution has been found to obey first order kinetics. The formation of CT complex of tetryl with EDA has been succesfully used to develop a spectrophotometric method for the quantitative determination of tetryl.
Energetics of AMMO
Authors: Bazaki Hakobu , Kubota Naminosuke 
Published: May 2005

AbstractThe thermal decomposition process and combustion wave structure of azide polymer were studied to determine the parameters which control the burning rate. The azide polymer studied was 3‐azidomethyl‐3‐methyl oxetane (AMMO) which contains energetic –N3 groups. From the experiments, it was found that the thermal decomposition process of AMMO consists of a two‐stage weight loss process: the first‐stage corresponds to an exothermic reaction which is caused by the scission of N‐N2 bond, and the second‐stage corresponds to the decomposition of the remaining fragments. The burning rate of AMMO is approximately 50% of the burning rate of GAP propellant and is as high as that of conventional double base propellant. The heat feedback from gas phase to the burning surface increase with increasing pressure. The burning surface temperature and the heat of reaction at the surface decrease with increasing pressure.
Thermal Decomposition of Energetic Materials 56. On the fast thermolysis mechanism of ammonium nitrate and its mixtures with mangnesium and carbon
Authors: Patil Dilip G. , Jain Sampat R. , Brill Thomas B. 
Published: May 2005

AbstractFast thermolysis studies of ammonium nitrate (AN) and its mixtures with magnesium and activated charcoal have been carried out by the Fourier transform infrared spectroscopy/temperature profiling technique. When subjected to rapid heating (ca. 80°C/s), AN Sublimes/decomposes around 300°. Sublimation dominates at ambient pressures. The IR‐active products of decomposition are NH3, NO2, N2O and H2O. Reaction schemes accounting for the products are proposed which involve proton transfer leading to NH3 by the decomposition products of HNO3. The decomposition of AN is significantly enhanced when AN is mixed with magnesium powder or charcoal, and occurs at as low a temperature as 135°C. Whereas NH3 is the major product of decomposition of ANMg mixtures, no NH3 is observed from ANC mixtures. The results are explained by the reaction of HNO3 and NH3 with Mg or C.
Assessment scheme for the chemical compatibility of materials with cast double base propellants
Authors: Keeton G. M. , Facer D. 
Published: May 2005

AbstractThe scheme for the compatibility assessment of materials with cast double base propellants as operated at Royal Ordnance Summerfield is described. Central to the scheme is the recognition that evaluation of the compatibility of materials must consider two areas of safety. These are on‐site process safety requirements, and rocket motor service life which includes safe chemicalstability and the long term functioning and reliability of a store. To rationalize testing, a system of compatibility testing to defined categories classified by the application and usage of a material is followed.
Thermal Decomposition of Azide Polymers
Authors: Oyumi Yoshio 
Published: May 2005

AbstractThermal decomposition of polyglycidyl azide (GAP) and bis(azidomethyl)oxetane/tetrahydrofuran copolymer (BAMO/THF) was studied by TGA and DSC in helium atmosphere, which was showing overall first‐order kinetics. The additional azide groups at terminal position in the molecular structure decomposed independently and increased the rate of decomposition. However, the decomposition kinetics was less affected by the additional azide groups in the main chain. The decomposition properties of aged polymer Samples were the same as those of untreated ones. Catocene significantly altered the decomposition temperatures of GAP and BAMO/THF. The speak temperature of DSC thermogram changed from 533 K to 494 K in GAP and from 535 K to 498 K in BAMO/THF. Like UV treatment, BAMO/THF with catocene was thermally cross‐linked during the aging at 343 K. Although BAMO/THF with catocene produced rubbery solids from the initial viscous liquids, there was no significant difference between the rate of decomposition of treated sample and that of untreated one.
Studies on the critical temperature of thermal explosion for 3‐Nitro‐1,2,4‐triazol‐5‐one (NTO) and its salts
Authors: Yi Xie , Rongzu Hu , Chaoqing Yang , Guofu Feng , Jihua Zhou 
Published: May 2005

AbstractThe critical temperature of thermal explosion for 3‐nitro‐1,2,4‐triazol‐5‐one (NTO) and its ethylenediammonium salt (ENTO), potassium salt (KNTO), copper salt (CuNTO) and lead salt (PbNTO) were obtained using the stationary theory of thermal explosion, the calculation formula of estimating the critical temperature of thermal explosion under non‐isothermal DSC condition, and the determination method for the critical temperature of thermal explosion of small‐scale solid explosive and its data treatment method. The results of the four methods are agreeable to each other, whose differences are within 5%. The results indicate that the heat‐resistance ability of NTO and its salts and of the common explosives, cyclotetramethylenetetranitramine (HMX), cyclotrimethylenetrinitramine (RDX), pentaerythritoltetranitrate (PETN) and tetryl decreases in the order HMX > NTO > ENTO > KNTO > RDX > PETN > tetryl > PbNTO > CuNTO.
Stability Studies on Pentaerythritol Tetranitrate
Authors: Om Reddy G. , Srinivasa Rao A. 
Published: May 2005

AbstractTyhe influences of acidity and dipentaerythritol hexanitrate (DiPEHN) on the thermal sensitivity of pentaerythritol tetranitrate (PETN) was studied using differential scanning calorimetry (DSC). Decomposition kinetics of PETN with or without DiPEHN, acidic PETN and DiPEHN were also studied by SC to evaluate Arrhenius parameters. The presence of sulphuric acid impurity decreased the thermal stability as well as the activation energy, whereas the nitric acid influence was negligible. Thermal stability of PETN was not affected by the presence of DiPEHN. DiPEHN showed better thermal stability and higher decomposition energy compared to PETN.
Experimental Study of Shaped Charges with built‐in asymmetries
Authors: Brown John , Softley I. D. , Edwards P. 
Published: May 2005

AbstractShaped charges have been manufactured and fired with built‐in asymmetries, some with the initiation system placed off‐centre, one with the casing around the explosive being of uneven thickness. The jets from these charges were radiographed, and the lateral and axial velocities of the particles were measured. The collapse process appears to be much more sensitive to the effects of decentration of the initiation point than to asymmetrical confinement. For small angles between the detonation wave and the axis of the liner, jet elements depart from the collapse zone at an angle similar to, and in the opposite sense from, the angle between the wave and the relevant part of the liner.The aim of this paper is to provide workers in the fields of the design, manufacture, and modelling of shaped charges with a database of quantitative information concerning the effects on the off‐axis motions of jet particles which occur if the charge and its initiation system lack perfect rotational symmetry. Pioneering work on this subject was done by Professor (then Doctor) Manfred Held in the early days of his work with Thomanek at Messerschmitt‐Bölkow‐Blohm. We offer some quantitative results to build on that pioneering work.
Electric spark and esd sensitivity of reactive solids (primary or secondary explosive, propellant, pyrotechnics) part one: Experimental results and reflection factors for sensitivity test optimization
Authors: Roux Michel , Auzanneau Max , Brassy Claude 
Published: May 2005

AbstractAn experimental study shows that spark energy transfer mechanisms are different for the explosive alone (HMX) and for the explosive containing 1% of graphite. This study is completed by literature data and underlines the need for parametric studies by systematically varying the electrodes gap as well as the spark duration to determine the true minimum value of the ignition energy. Grain size and shape are very important factors. The influence of the electrode shape is also discussed, as well as the environmental conditions. These data allow us to determine the conditions for testing the electric spark sensitivity of solids. The tests are then performed at a small scale.Moreover, for ionic solids or substances made of an electrically insulating matrix containing conductive inclusions, particular phenomena appear when they are submitted to electric fields for a certain time. These phenomena justify the development of specific tests to determine the capacitive discharge sensitivity.
Volatility of NENA and Other Energetic Plasticizers determined by thermogravimetric analysis
Authors: Cartwright R. V. 
Published: May 2005

AbstractThermogravimetric analysis (TGA) at constant temperature was used to measure weight loss of plasticized nitrocellulose (NC) propellants due to vaporization of plasticizer. Plasticizers consisted of three 2‐nitroxyethylnitramine (NENA) compounds, diethylene glycol dinitrate (DEGDN), and nitroglycerin (NG). Initial concentration of plasticizer and degree of nitration of NC were also varied. Each propellant was tested at three temperatures. Plasticizer diffusivities (D) and their activation energies were calculated. Observed trends were generally consistent with calculated plasticizer solubility parameters, expected increases in molecular mobility for more highly plasticized materials, and the more polar and more disordered structure of NC with a lower degree of nitration. Some unexpected effects could be explained by changes in entropy of activation due to variation in plasticizer or NC structure. In general, the NENA plasticizers had lower vaporization rates than DEGDN or NG, suggesting that plasticizer losses during manufacturing or storage of practical formulations should not be a problem.
Thermal Decomposition of HMX and Mixtures
Authors: Hussain G. , Rees G. J. 
Published: May 2005

AbstractThermal decomposition of pure HMX shows DSC endothermic peaks at 210°C from β to γ phase transformation and at 285°C from the HMX melting followed by an instantaneous exothermic decomposition leading to a strong peak at 290°C and a very strong DTG peak at 325°C with a mass loss of 95%. However, the GS‐2 mixture shows two DSC exothermic peaks at 225°C and 270°C assigned to nitroguanidine etc. and HMX decomposition. Addition of NH4ClO4 to HMX causes the decomposition to take place before melting and decomposition peak is lowered to 230°C. However in the case of GS‐2, a strong effect was observed and the amount of the mixture was to be decreased to obtain a reasonable DSC curve. This shows that the addition of NH4CIO4 to HMX increases the decomposition of HMX, however this effect is more pronounced in GS‐2 mixture. Even the minimum concentration of NH4CIO4 tested (10%) shows strong effect.The addition of NH4NO3 to HMX and GS‐2 shows DSC exothermic decomposition peaks at 272°C and 245°C, showing a contribution from NH4NO3 decomposes near to the decomposition of HMX, it does not show a strong effect on the decomposition of HMX/GS‐2 as compared to NH4ClO4. Addition of KClO4, NaClO4 and KNO3 don't show any effect in these thermoanalytical studies.
Nitroureas II. Synthesis of Bicyclic Mono‐ and Dinitrourea Compounds
Authors: Pagoria Philip F. , Mitchell Alexander R. , Jessop Edward S. 
Published: May 2005

AbstractWe report the synthesis and characterization of several bicyclic mono‐ and dinitrourea compounds as energetic materials and discuss their use as precursors to other energetic compounds. The new nitrolyzing reagent, trifluoromethanesulfonic acid anhydride/20% N2O5/nitric acid, will also be described.
On the validity of the thermal explosion model in shock wave initiated nitromethane
Authors: Pujols Henri‐Christian , Pouligny Brigitte 
Published: May 2005

AbstractBy means of Perot Fabry Velocimetry (PFV) we recorded material velocities generated by an intense shock wave (P > 70 kbar) in pure nitromethane. Our experiments show that nitromethane does not behave according to the Campbell‐Travis model for detonation in liquid explosives. We do not find any evidence for a so‐called superdetonation, which would start behind and overtake the pressure shock wave. Our recordings of material velocities show a behavior of the liquid explosive very similar to that of solid polycrystalline explosives and are compatible with the heterogeneous decomposition scheme.
Estimation of thermodynamic stability conditions and perspectives for synthesis of covalent carbon nitride
Authors: Odintsov Victor V. , Pepekin Vitaly I. 
Published: May 2005

AbstractThe present work is devoted to the determination of conditions of thermodynamic stability of carbon nitride having structure of β‐C3N4. The thermodynamic functions of crystalline covalent carbon nitride required for thermodynamic reckoning of parameters of formation of carbon nitride were determined on the base of the Debye theory with the characteristic temperature varied in the range from 1000 K to 2500 K. The formation enthalpy of carbon nitride was estimated on the base of the energy of atomization and formation enthalpy of a mixture of atomized carbon and nitrogen. The resulted quantity of the standard formation enthalpy of covalent carbon nitride at 298.15 K made up 4.47 kcal/mol. Thermodynamic computations were accomplished with the use of the Automated System of Thermodynamic Reckonings and Algorithms ASTRAL. Behavior of the gaseous phase of a chemical system was described by the BKW‐RR equation of state. Carbon nitride was considered to be incompressible. The region of thermodynamic stability of covalent carbon nitride is computed. It is shown that in contrast to the carbon condensation into graphite the pressure of condensation of β‐C3N4 when adding other chemical elements to a thermodynamic system can not only increase but decrease as well. Consideration of detonation and explosion processes in high explosives shows a way for practical synthesis of covalent carbon nitride.
Phase State of Nitrocelluloses Plasticized with Trinitroglycerin
Authors: Lotmentsev Yu. M. , Pleshakov D. V. 
Published: May 2005

AbstractThis work aims at an investigation of the thermodynamical compatibility of nitrocellulose with nitroglycerin. The study resulted in the construction of the phase diagram for the nitrocelluloses‐trinitroglycerin system. The diagram can be used in predicting the thermodynamical stability and phase constitution of the composition prepared on the basis of these components.
Stationary phases. Part 39(1): Trace analysis of RDX in HMX on a novel copoly(vinylthiazole‐vinylimidazole) stationary phase by HPLC
Authors: Shieh Kuan‐Jiunn , Lee Sheau‐Long , Chang Chenq‐Shyong , Wen Cheng‐Hau , Den Tschau‐Gan 
Published: May 2005

AbstractA method for the HPLC analysis of RDX and HMX on a novel copoly(vinylthiazole‐vinylimidazole) stationary phase [P(Th‐Im) phase] is described. Special elution order of RDX and HMX on this phase using methanol/water (60/40∼90/10) as mobile phase is HMX > RDX, which is quite different from those on a commercial RP‐18 phase. The chromatographic selectivities (α‐values) between RDX and HMX are 2.40∼2.55. This advantage can be used to identify the limited impurity of ca. 1 ppm RDX in HMX during the manufacture of HMX.
Ignition of pyrotechnic mixture by means of a laser diode. Part II: Experimental study
Authors: Roux M. , Gillard Ph. 
Published: May 2005

AbstractAn experimental device using a laser diode is described. The laser diode is coupled with a 100 μm diameter optical fiber. Lasering times are about one ms and the energy of the pulse ranges from 0.5 mJ to 5 mJ. Output power provided by optical fiber is about 0.5 W and the wavelength of radiation is 820 nm. Before each shot the pulse energy is measured by means of a joule meter. It allows a very accurate determination of the amount of energy transferred to the solid explosive. A small reactor containing about 40 mg of explosive is used. It allows to initiate combustion with a direct contact between the output of an optical fiber and the solid explosive. Three pyrotechnic compounds were tested and tests have shown that it is possible to ignite Zr/KClO4 and Zr/PbCrO4 mixtures. Experimental results are discussed and compared with numerical simulations presented in Part I.
Shaped Charge Jet Tail Velocity
Authors: Me‐Bar Yoav , Partom Yehuda 
Published: May 2005

AbstractThe impact of a shaped charge jet, created by a stationary charge onto a moving target, creates an elongated cut on the target face. The length of the cut, together with additional data about the charge and target configuration, enables the calculation of the jet tail velocity. It was found that this velocity increases with the stand‐off distance between the charge and the target. A possible cause for this acceleration is that the jet material is under tension due to the velocity gradient along it and the stress throughout it equals the dynamic flow stress of the material. This stress pulls on the jet material towards the center of gravity and tends to reduce the velocity gradient, i.e. decelerate the tip and accelerate the tail. 1D simulations show that this mechanism results in a constant acceleration of the tail, and that the acceleration depends on the flow stress of the jet material, hence on its temperature. Based on the experimental evidence and on the simulations, it is postulated that in addition to the velocity gradient along the jet, there are temperature and strength gradients along it, as well.
Ribosome‐inhibiting proteins, retroviral reverse transcriptases, and RNase H share common structural elements
Authors: Ready Michael P. , Katzin Betsy J. , Robertus Jon D. 
Published: May 2005

AbstractPlant ribosome‐inhibiting proteins are shown to be homologous at the domain level to RNase H form Escherichia coli and to two regions of the pol gene product of retroviral reverse transcriptases. One of these regions carries the viral integrase or int function, while the other has previously been suggested to contain the viral RNase H exo activity. Several residues conserved among the ribosome inhibitors, E. coli RNase H, and the integrase proteins are seen to occupy a prominent cleft in the tertiary structure of the ribosome inhibitor ricin, suggesting roles in binding or catalysis. It is likely that these homologous sequences represent modern derivatives of an ancient protein‐folding unit capable of nucleic acid binding and modification which has been incorporated into a variety of enzyme functions.
The three‐dimensional structure of recombinant bovine chymosin at 2.3 Å resolution
Authors: Gilliland Gary L. , Winborne Evon L. , Nachman Joseph , Wlodawer Alexander 
Published: May 2005

AbstractThe crystal structure of recombinant bovine chymosin (EC 3.4.23.4; renin), which was cloned and expressed in Escherichia coli, has been determined using X‐ray data extending to 2.3 Å resolution. The crystals of the enzyme used in this study belong to the space group I222 with unit cell dimensions a = 72.7 Å, b = 80.3 Å, and c = 114.8 Å. The structure was solved by the molecular replacement method and was refined by a restrained least‐squares procedure. The crystallographic R factor is 0.165 and the deviation of bond distances from ideality is 0.020 Å. The resulting model includes all 323 amino acid residues, as well as 297 water molecules. The enzyme has an irregular shape with approximate maximum dimensions of 40 × 50 × 65 Å. The secondary structure consists primarily of parallel and antiparallel β‐strands with a few short α‐helices. The enzyme can be subdivided into N‐ and C‐ terminal domains which are separated by a deep cleft containing the active aspartate residues Asp‐34 and Asp‐216. The amino acid residues and waters at the active site form an extensive hydrogen‐bonded network which maintains the pseudo 2‐fold symmetry of the entire structure. A comparison of recombinant chymosin with other acid proteinases reveals the high degree of structural similarity with other members of this family of proteins as well as the subtle differences which make chymosin unique. In particular, Tyr‐77 of the flap region of chymosin does not hydrogen bond to Trp‐42 but protrudes out in the P1 pocket forming hydrophobic interactions with Phe‐119 and Leu‐32. This may have important implications concerning the mechanism of substrate binding and substrate specificity.