bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrogenated Hydroxy‐Terminated Polyisoprene as a Fuel Binder for composite solid propellants
Authors: Iwama Akira , Hasue Kazuo , Takahashi Terue , Matsui Kiyoshi , Ishiura Kazunari 
Published: May 2005

AbstractThe synthesis and application of hydrogenated hydroxy‐terminated polyisoprene (HHTPI) to a fuel binder of composite solid propellants were attempted. An HHTPI prepolymer was synthesized through the hydrogenation for the hydroxy‐terminated polyisoprene (HTPI) in the presence of nickel and zirconium catalysts over kieselguhr in 2.0 MPa hydrogen and at 443 K – 453 K for 24h. A prepolymer of a number‐averaged molecular weight 2500–3800, provided a viscosity level required for the use of a fuel binder from which solid propellant can be possibly made by means of direct casting method. Thermal stability and aging characteristics of HHTPI elastomer against environmental attacks are superior to those of HTPB. Some plasticizers and bonding agents can bring about the acceptable mechanical properties to the propellant grains mainly composed of HHTPI, ammonium perchlorate and aluminium powder. The linear burning rates of HHTPI‐based propellants are at the same level with that of HTPB‐based propellants. However, the composition that gives the maximum performance with HHTPI‐based propellants, shifts to 1–2 wt% fuel‐rich side from the most adequate fuel content 12 wt% in HTPB/AP/Al. The HHPTI propellants indicated the similar burning rate as HTPB‐based propellants in the linear burning rates in spite of the comparatively poor ignitability. Nevertheless, the static tests of 100 mm dia. sounding rocket motors are successfully performed by an ignition operation at the pressurized condition. The ballistic performances are not inferior to those of the HTPB‐based propellants.
Low and High Order Detonation in Tetryl
Authors: Leiper G. A. , Cooper J. 
Published: May 2005

AbstractThe detonation behaviour of tetryl has been investigated by analysing published charge diameter effect data for two mesh sizes of powders, using slightly divergent flow theory. Evidence found within the published data for the existence of high and low order detonation velocities regimes has been substantiated. The form of the global heat release function during low order detonation was found to be of the hot spot/grain burning type, and during high order detonation, of the thermal explosion type. Particle size effects are discussed both for low and high order detonation. The observed stability of low order detonation at the smaller charge diameters is explained in the model used, which predicts a ‘forbidden zone’ in shock velocity/inverse charge diameter space. The kinetics are discussed in terms of the pressure dependent functional form used in the CPeX detonation model, and models of hot spot formation in powder explosives.
Solid Propellant Degradation Kinetics via headspace sampling gas chromatography
Authors: Judge Michael D. 
Published: May 2005

AbstractThe degradation kinetics of solid rocket propellant based on a glycidyl azide polymeric binder with ammonium nitrate were determined by gas chromatographic quantitation of the headspace gases over heated samples. This approach was found to allow the determination of degradation at temperatures approaching ambient. An Arrhenius plot was constructed from the data and kinetic parameters, including activation energy and relative rates of degradation, were calculated. Two different batches of propellant were found to exhibit similar degradation kinetics, although one was estimated to have a shorter service life based on the relative volumes of gases liberated.
Influence of product species selection on thermochemical equilibrium calculations. Part I: Energetic materials
Authors: Greenlee C. L. , Butler P. B. 
Published: May 2005

AbstractChemical equilibrium calculations are made for a number of Carbon C, Hydrogen H, Nitrogen N, and Oxygen O, explosive compositions. A methodology is established to systematically limit the number of product species available in thermochemical equilibrium calculations. The calculations are then compared with “baseline” results obtained using an extensive product species library consisting of 900 gas‐phase and 600 condensed‐phase product species. Errors in bulk thermodynamic properties (detonation velocity and pressure) and in product chemical composition are quantified in terms of the number of species considered as products of reaction. The properties at states along an expansion isentrope are also presented.
High energetic materials: Reaction of Azides with Dioxygenyl Salts
Authors: Holfter Hagen , Klapötke Thomas M. , Schulz Axel 
Published: May 2005

AbstractThe reactivity of sodium azide, activated sodium azide and hydrazinium azide towards various dioxygenyl salts was studied. Under no circumstances the formation of dioxygenyl azide, O2N3, could be observed. This is in agreement with high level quantumchemical ab initio computations at correlated level (MP2, PMP2, CISD), predicting the decomposition of hypothetical O2+(g)/N3−(g) to be thermodynamically highly favorable (MP2: −326; PMP2: −328; CISD; −369 [kcal/mol]). The combustion of O2BF4 with either N2H5N3 (spontaneous reaction on contact in a coaxial solid‐propellant system) or NaN3 (safe to handle, highly exothermic reaction after ignition) is discussed in terms of high‐energy‐density materials (HEDM).
The Use and Application of Red‐Phosphorous Pyrotechnic Composition for camouflage in the infrared region of radiation
Authors: Klusáček Ladislav , Navrátil P. 
Published: May 2005

AbstractUnder laboratory conditions, there were detected burning products of pyrotechnic compositions based on red phosphorus with epoxy resin being especially trihydrogenphosphoric acid, tetrahydrogendiphosphoric acid and mixture of cyclo‐triphosphoric acid, cyclo‐tetraphosphoric acid and cyclo‐hexaphosphoric acid. In burning products of pyrotechnic composition with magnesium added there was detected only cyclo‐triphosphoric acid among cyclic derivatives. Phosphorous aerodispersions generated from smoke grenades containing these pyrotechnic compositions under field conditions could screen infrared radiation (0.82 μm, 3–5 μm, 10.6 μm wavelengths) with high efficiency. Examined pyrotechnic compositions of plasticized red phosphorus with epoxy resin proved to be suitable for smoke grenades of modern construction with both fast and slower generation of phosphorous aerodispersion.
Modification of Thermal Theories to Solid Propellant Ignitibility
Authors: Su Fu‐Hu 
Published: May 2005

AbstractThe conventional thermal theories are inventively modified for analyzing the ignition behaviors of solid propellants. Based on the modification of the thermal theory with the boundary condition of constant heat flux, the effects of heat flux, pressure, threshold of heat flux and absorbability on the radiant ignition of solid propellant are elaborated. The innovations of theoretical analyses are consistent with most of experimental results depicted in literatures. That the increase of hot gas velocity increases the ignition time of solid propellant is verified to be attributable to the decrease of hot gas temperature, ascertaining insight of the thermal theory with the boundary condition of flowing hot gas. In addition, a tentative estimation of pressurization rate effect on ignition time of solid propellant is proposed.
Influence of energetic materials on the energy‐output of gun propellants
Authors: Volk Fred , Bathelt Helmut 
Published: May 2005

AbstractFor the formulation and preparation of gun propellants containing high energetic compounds, methods have been described how to improve the performance. In addition thermodynamic data such as flame temperature, mole number, mean molecular weight, heat of explosion and specific energy were discussed, which are of main influence for the energy‐output of energetic materials. In connection with the improvement of performance, a list of components was established, which could be used to increase the energy without increasing the sensitivity of the propellants. At first, the aim was to replace conventional plasticizers by several energetic plasticizers. Taking into account different propellant formulations, the thermodynamic parameters have been calculated which are of interest for improvement of the specific energy. On the other hand, nitramine propellants manufactured at our Institute using different binder systems such as polybutadiene (PB), glycidylazide polymer (GAP) and cellulose acetate butyrate (CAB) have been investigated in a closed bomb in order to evaluate the energy‐output and in addition the reaction products by gas analysis. The performance of these LOVA‐propellants was discussed in connection with heat of formation, oxygen balance and the kind of polymeric binder system. Finally, energetic compounds such as NTO, CL‐20, TNAZ, ANTA and ammonium dinitramide (ADN) have been calculated using the ICT‐Thermodynamic Code, in order to assess the energy‐output and to be able to discuss a possible improvement of the performance.
Kinetic modelling of the stabilizer consumption and of the consecutive products of the stabilizer in a gun propellant
Authors: Bohn Manfred A. , Eisenreich Norbert 
Published: May 2005

AbstractDiphenylamine is used for the stabilization of solid propellants based on nitrocellulose. It reacts with the autocatalyticly acting decomposition product of nitrocellulose and forms consecutive products, which also stabilize. The kinetics of these stabilizing reactions are described by four reaction models. With respect to DPA and the DPA consecutive products the models have one, two and four steps. The four step model contains the DPA consecutive products up to trinitro‐DPA. By approximations an analytical equation for the stabilizer decrease could be derived, which describes the stabilizer consumption very well. The other equation systems have been integrated numerically by a Runge–Kutta procedure and their reaction rate constants have been obtained by a non‐linear least squares fit parameter calculation. This allows an evaluation of the reaction kinetic models. Relative reactivities of the DPA consecutive products with respect to DPA are calculable with the obtained reaction rate constants and an effective DPA concentration can be established. The different reactivities of mixed stabilizers as MNA and 2‐NO2‐DPA can be described with the presented method of modelling.
Controlled pyrolysis of the new energetic binder azide polyester PAP‐G
Authors: Pfeil Achim , Löbbecke Stefan 
Published: May 2005

AbstractThe degradation mechanism of the azide polyester PAP‐G (poly‐2,2‐bis(azidomethyl)‐1,3‐propandiol‐glutarate) on controlled pyrolysis differs from that of the polyether GAP (glycidyl azide polymer). The decomposition is more intensive, involves more of the carbon backbone and occurs at lower temperatures. As an energetic component in a propellant it tends to disintegrate at an early stage giving off cabonaceous material of the polymer structural backbone.Mixed metal oxides in the doped binder samples affect neither the reaction enthalpy nor the reaction products. However, they accelerate the nitrene formation by shifting the reaction interval to lower temperatures. Shifts up to 20 K were observed. In the case of PAP‐G the effect is most expressed by the additive MOVO whereas for GAP, in opposite, copper chromite is most effective.
Radiation Emitted from Rocket Plumes
Authors: Deimling Lukas , Liehmann Wolfgang , Eisenreich Norbert , Weindel Martin , Eckl Wilhelm 
Published: May 2005

AbstractThe signature of rocket plumes can be used for detection, identification and guidance of rockets. The objective was to investigate the signature of various types of solid rocket propellants by application of spectroscopic methods. The emission and transmission characteristics of plumes were studied experimentally, the results were analyzed based on molecular bands and continuum radiation. The model formulations include a nitramine propellant, a double‐base propellant and a composite propellant. Applied were rapid‐scanning filter wheel spectrometers for the wavelength region from 1.2 μm to 14 μm with a time resolution of 50 spectra/s and a wavelengths resolution of 1% of actual wavelength. The UV/VIS wavelengths region was recorded by an OMA system with wavelength resolution of 0.1 nm and 1 nm and time resolution of 10 spectra/s. Molecular bands of water and carbon dioxide dominate in the near infrared and infrared. Depending on composition, continuous radiation indicates particles in the rocket exhaust. A code was developed to calculate molecular bands and continuous radiation using temperature and species distributions found by thermodynamic estimation to obtain the radiance of the plume. Comparison with experimental data delivered plume temperatures.
Size Effect and Detonation Front Curvature
Authors: Souers P. Clark 
Published: May 2005

AbstractA simple theory relates the size effect (decrease of the detonation velocity with decreasing radius) of a cylinder with its average sonic reaction zone length, 〈xe〉, i.e. the distance from first reaction to the sonic plane. The size effect is described by

where R0 is the radius, Us and D the detonation velocities at R0 and at infinite size and σ is a function describing the extent of wall motion, which is calibrated using four explosives. In this theory, the cylindrical symmetry imposes a quadratic shape to the detonation front. The lag distance at the edge of the cylinder, L0, is related to the reaction zone length by 〈xe〉 ≈︁ L0. Collected results are presented for 56 measured curvatures on 26 explosives, with reaction zone lengths varying from 0.1 mm to 30 mm.
Ignition of pyrotechnic mixture by means of a laser diode. Part I: Numerical modelling
Authors: Gillard Ph. , Roux M. 
Published: May 2005

AbstractA numerical model of the heating and ignition of a reactive solid by a laser beam has been developed. A transient, two‐dimensional heat equation was solved numerically using an explicit scheme. A nonlinear source term (Arrhenius equation) complicates the analytical resolution of this type of problem. Laser beam absorption is considered in a few micrometer depth. Influence of depth absorption coefficient is investigated. Influence of laser power density, lasering time and thermal diffusivity on ignition are examined by this model. The developed numerical model has been used to design a laser ignition system for explosive substances. It has been shown that ignition by a 0.6 W laser diode at a fiber optics output is feasible.
Mechanical and Swelling Properties of Copolyurethanes based on Hydroxy‐Terminated Polybutadiene and its hydrogenated analog
Authors: Sekkar V. , Krishnamurthy V. N. , Jain S. R. 
Published: May 2005

AbstractCopolyurethane networks based on Hydroxy‐Terminated Polybutadiene (HTPB) and Hydrogenated HTPB (HHTPB) have been synthesized using toluene diisocyanate as curing agent. Addition of HHTPB results in enhancement of properties, such as tensile strength and modulus, at nearly the same elongation values. It is possible to generate urethane networks with similar modulus and tensile strength with widely varying elongation values and vice versa by jointly altering the comonomer ratio, and the r (NCO/OH equivalent ratio) value. Dynamic mechanical studies have been made to determine the storage and loss moduli, and their variations with temperature. Solid propellant formulations processed with the copolyurethanes have been characterized for their mechanical strengths and burn rates.
Evaluation of a New Primary Explosive: Nickel Hydrazine Nitrate (NHN) complex
Authors: Shunguan Zhu , Youchen Wu , Wenyi Zhang , Jingyan Mu 
Published: May 2005

AbstractNHN is a thermally and hydrolytically stable solid, easily prepared from available raw materials. Its preparation liquor can be used repeatedly, which means no waste‐water pollution in industrial manufacture. NHN is not sensitive to impact, friction, or electrostatic charge, but is more sensitive to flame. It is demonstrated that NHN is suitable as a replacement for lead azide as an intermediate charge in commercial detonators.
Flamespreading during Base Ignition of Propellant Charge: Theoretical and experimental studies
Authors: Jaramaz Slobodan 
Published: May 2005

AbstractIn the paper theoretical modeling of flamespreading through granular propellant charge during base ignition is given. The theoretical model includes the balance equations for the gas and solid phase, as well as necessary constitutive laws. The stable convergent numerical procedure for solution of the system of equations is developed. This procedure is included in computational program FSPC (Flame‐spreading through Propellant Charge). The program FSPC enables investigations of influence of ignition material, physical and chemical characteristics of propellant and propellant charge loading density on the flamespreading process. The experimental investigations by an especially designed apparatus are performed. The verification of the theoretical‐numerical access through the comparison with the experimental data (pressure vs. time and locations, flamespreading velocity, propellant grains displacements) is carried out. The entire access makes possible more successful solutions of many interior ballistics problems.
Flexibility of the DNA‐binding domains of trp repressor
Authors: Lawson Catherine L. , Zhang Rong‐guang , Schevitz Richard W. , Otwinowski Zdzislaw , Joachimiak Andrzej , Sigler Paul B. 
Published: May 2005

AbstractAn orthorhombic crystal form of trp repressor (aporepressor plus L‐tryptophan ligand) was solved by molecular replacement, refined to 1.65 Å resolution, and compared to the structure of the repressor in trigonal crystals. Even though these two crystal forms of repressor were grown under identical conditions, the refined structures have distinctly different conformations of the DNA‐binding domains. Unlike the repressor/aporepressor structural transition, the conformational shift is not caused by the binding or loss of the L‐tryptophan ligand. We conclude that while L‐tryptophan binding is essential for forming a specific complex with trp operator DNA, the corepressor ligand does not lock the repressor into a single conformation that is complementary to the operator. This flexibility may be required by the various binding modes proposed for trp repressor in its search for and adherence to its three different operator sites.
Molecular interactions in protein crystals: Solvent accessible surface and stability
Authors: Islam Suhail A. , Weaver David L. 
Published: May 2005

AbstractThe accessible surface areas of 58 monomeric and dimeric proteins, when measured in the crystalline environment, are found to be simply related to molecular weight. The loss of accessible surface when the proteins go from a free to their crystalline environment is well defined, implying that the hydrophobic interaction, which has been found to contribute to protein folding and stability in living systems, also contributes to protein crystal stability.
Acid helix‐turn activator motif
Authors: Zhu Qing‐Lin , Smith Temple F. , Lathrop Richard H. , Figge James 
Published: May 2005

AbstractA common sequence/structural motif pattern has been identified within the steroid/thyroid hormone receptors and other transcriptional activators using a new massively parallel symbolic learning assistant computer system. The pattern appears nearly diagnostic of transcription activation, including relative activation strength, among nuclear and DNA‐binding prokaryotic proteins. In cases where mutation/deletion/chimeric studies have identified the activation domain, the pattern matches within that domain. These facts and the nature of the pattern itself strongly support the idea that the patterned domain is directly involved in a protein‐protein transcription activation interaction.
Conformational and helicoidal analysis of the molecular dynamics of proteins: “Curves,” dials and windows for a 50 psec dynamic trajectory of BPTI
Authors: Swaminathan S. , Ravishanker G. , Beveridge David L. , Lavery Richard , Etchebest Catherine , Sklenar Heinz 
Published: May 2005

AbstractA new procedure for the graphic analysis of molecular dynamics (MD) simulations on proteins is introduced, in which comprehensive visualization of results and pattern recognition is greatly facilitated. The method involves determining the conformational and helicoidal parameters for each structure entering the analysis via the method “Curves,” developed for proteins by Sklenar, Etchebest, and Lavery (Proteins: Structure, Function Genet. 6:46–60, 1989) followed by a novel computer graphic display of the results. The graphic display is organized systematically using conformation wheels (“dials”) for each torsional parameter and “windows” on the range values assumed by the linear and angular helicoidal parameters, and is present in a form isomorphous with the primary structure per se. The complete time evolution of dynamic structure can then be depicted in a set of four composite figures. Dynamic aspects of secondary and tertiary structure are also provided. The procedure is illustrated with an analysis of a 50 psec in vacuo simulation on the 58 residue protein, bovine pancreatic trypsin inhibitor (BPTI), in the vicinity of the local minimum on the energy surface corresponding to a high resolution crystal structure. The time evolution of 272 conformational and 788 helicoidal parameters for BPTI is analyzed. A number of interesting features can be discerned in the analysis, including the dynamic range of conformational and helicoidal motions, the dynamic extent of 2° structure motifs, and the calculated fluctuations in the helix axis. This approach is expected to be useful for a critical analysis of the effects of various assumptions about force field parameters, truncation of potentials, solvation, and electrostatic effects, and can thus contribute to the development of more reliable simulation protocols for proteins. Extensions of the analysis to present differential changes in conformational and helicoidal parameters is expected to be valuable in MD studies of protein complexes with substrates, inhibitors, and effectors and in determining the nature of structural changes in protein–protein interactions.