bluuebunny/crossref_metadata_2025_split huggingface dataset:
Curing reaction of saturated aliphatic polyester modified unsaturated polyester resins
Authors: Liu S. B. , Yang J. F. , Yu T. L. 
Published: December 2004

AbstractTwo series of unsaturated polyesters (UPE from isophthalic acid, fumaric acid, and propylene glycol) were prepared. In series‐A resins, UPEs wee thickened with isocyanate‐terminated saturated aliphatic polyestes, i.e., an isocyanate‐terminated polycaprolactone diol (PE‐di‐OL), through reaction of the isocyanate group with the hydroxyl group of the UPE. In series‐B resins, the UPEs were mixed with saturated aliphatic polyesters i.e., PE‐di‐OL. The curing reaction of these two series of UPEs with styrene was studied by using differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). The DSC data show that for a fixed PE‐di‐OL molecular weight, the curing reaction rate of series‐A UPE is faster than that of series‐B UPE. The variation of microgel size during curing ws studied by GPC. These results revealed that microgel formation has a great effect on the kinetics of cure for the unsaturated polyester‐styrene system. The curing of these two series of UPEs is found to strongly depend on the compatibility of the components in the curing system.
The Characterisation of the Flow of Aerated Powders
Authors: Lloyd Philip J. , Webb Peter J. 
Published: December 2004

AbstractThis paper reviews the development of a new annular shear cell for the characterisation of aerated powders. The cell enables the measurement of the transmitted shear stress at degrees of aeration below fluidisation. Results are presented for three powders, Alumina, Phosphate Rock and Sodium Carbonate. These show a large reduction in shear stress for small quantities of air entrainment and a transition from normal coulomb‐solid flow to liquid‐type flow at high shear rates. This characterisation enables an explanation of the flooding phenomena experienced in powder handling processes.
Scattering of a Gaussian Beam by a Sphere Using a Bromwich Formulation: Case of an arbitrary location
Authors: Gouesbet Gérard , Maheu Bruno , Gréhan Gérard 
Published: December 2004

AbstractA complete theory of Gaussian beam scattering by a sphere is exposed. It is a generalization of the Lorenz‐Mie Theory to the case of Gaussian beam illumination. The spherical, isotropic and homogeneous scatterer may be located anywhere with respect to the beam. The Bromwich Scalar Potentials are used to solve the scattering problem and expressions are obtained for the scattered field (both in the near field and far field regions), the scattered intensities and the phase angle. In the limit of special cases the expressions agree with previous works restricted to more particular problems.
Determination of the Fractal Dimension of the Irregular, Compressive Stress‐Strain Relationships of brittle, crumbly particulates
Authors: Peleg Micha , Normand Mark D. 
Published: December 2004

AbstractThe apparent fractal dimension of normalized rugged compressive force‐deformation curves of two types of brittle particulates was determined using the blanket algorithm. Although the shape of the original force‐deformation relationships of the individual specimens was irreproducible, the apparent fractal dimension of the normalized data was fairly constant and characteristic of the material. The applicability of the algorithm and the validity of the results were tested with computer simulated relationships generated with a set of Weierstrass functions whose fractal dimension was known a‐priori. It is demonstrated that as long as the resolution along the two axes is the same, the fractal dimension so calculated provides an absolute rather than a relative measure of the relationship's jaggedness.
Correction of the Effect of Particle Shape on the size distribution measured with a laser diffraction instrument
Authors: Heffels Camiel M. G. , Verheijen Peter J. T. , Heitzmann Daniel , Scarlett Brian 
Published: December 2004

AbstractThis paper gives a theoretical basis for calculating Fraunhofer diffraction patterns of arbitrary polyhedron particles. It is shown that this solution can be used for calculating a scatter matrix adapted to the particle shape in a straightforward manner. Some simulations were made to show the difference between the size distribution by volume obtained with a scatter matrix for spheres and with that for the appropriate shape. Finally, some experimentally measured signatures from platelets and rods are evaluated in order to show that the spherical equivalent diameter could be accurately retrieved.
Calculating Shape Factors from Particle Sizing Data
Authors: Barreiros Fatima M. , Ferreira Paulo J. , Figueiredo M. Margarida 
Published: December 2004

AbstractIt is well established that particle size and shape substantially influence the bulk properties of powdered materials. Although these characteristics are closely interrelated, the tendency has been to analyse the particle size independently from particle shape. The aim of this work was the assessment of particle shape through particle sizing data. For this purpose, three different particle shape materials – glass beads (spherical), crushed glass (moderately irregular) and mica (lamellar) – were tested, employing four particle sizers. The shape factor selected was the Wadell's sphericity, which was evaluated utilizing distinct equations. The comparison of the results reveals problems arising from the use of approximations rather than more fundamental equations.
On the Time‐Dependence of the Force in Tests of impact sensitivity
Authors: Wild R. 
Published: December 2004

AbstractIn order to characterize the small fall‐hammer of BAM (Bundesanstalt fur Materialprüfung) its mechanical properties were determined. Using the theory of the forces between two colliding bodies expressions were derived to describe the tester which were validated by the experimental measurements. I t was found that forces of up to 21 kN were transmitted to the anvil (for 1 kg weight dropping through 0,s m) and that the impact times ranged from about 150 f i s for the small weights to about 500 f i s for the large weights. It was also found that in addition to the expected kinetic energy dependence of the forces on the anvil there was also a dependence on the actual weight used.
A General Model for the Shock Initiation of Explosives
Authors: Walker F. E. , Wasley R. J. 
Published: December 2004

AbstractA general model for the shock initiation of explosive reaction in chemical explosives is proposed. The model is based on the concepts of: (1) the kinetics of decomposition in which ions and free radicals produced by the shock wave shear forces initiate chain reactions that contribute to and accelerate the decomposition produced by the thermally activated molecules; (2) the formation of statistically random reaction sites whose number in a specific explosive is a direct function of the shock pressure as the shock transits the explosive; and (3) a critical‐ energy‐fluence requirement for initiation. This model appears to apply to explosive reaction in gases, liquids, and solids.
Thermal Decomposition of Hydrazinium Diperchlorate
Authors: Pai Verneker V. R. , Sharma A. N. , Jain S. R. 
Published: December 2004

AbstractThe mechanism of the thermal decomposition of hydrazinium diperchlorate (HP‐2) has been investigated in the temperature range 100–200°C. l he decomposition can be represented by the chemical equations:

The solid state decomposition up to 180°C ensues with an activation energy of 23 kcal/mole whereas above 180°C in the molten state the activation energy is 35 kcal/mole.
Effect of Intentional Impurities, Aging, Particle Size and Pre‐Irradiation on the Thermal Decomposition of Hydrazinium Diperchlorate
Authors: Verneker V. R. Pai , Sharma A. N. , Jain S. R. 
Published: December 2004

AbstractThe effect of dopants, aging, particle size and pre‐irradiation on the thermal decomposition of hydrazinium diperchlorate (HP‐2) has been investigated. Data on the uptake of N2H6S04 indicate that these impurities are distributed homogenously in HP‐2. Anion vacancies have been found to sensitize the decomposition while cation vacancies desensitize. The mechanism of the decomposition has been discussed in terms of the migration of ionic species and electron transfer from CIO4− ion to N2H62+ ion.The decomposition is found to desensitize with age. The aging effect is attributed to a decrease in anion vacancy concentration with age. Particle size does not seem to have any effect on the decomposition of HP‐2. Pre‐irradiation is found to affect the decomposition appreciably only when HP‐2 is irradiated for longer durations (> 1 hr), the effect being observed only during the later stages of the decomposition (01 > 0.3).
Simple and Rapid Determination of Small Amounts of Sulphate in Cellulose Nitrate
Authors: Dawoud Abdel‐Fattah , Soliman Adly A.‐W. , Saad H. A. 
Published: December 2004

AbstractOxidative decomposition of cellulose nitrate was brought about by simple wet‐ashing in a beaker with nitric acid and the digest‐residue was further oxidised with 30% hydrogen peroxide, followed by evaporation to dryness. Interferences arising from use of hydrogen peroxide were later avoided by digesting with nitric acid and Evaporation to dryness. Complete oxidation was achieved in approximately one hour. The digests allow rapid sulphate determination by the lead nitrate‐dithizone titration method. The method was greatly successful for analyzing both the unstabilized cellulose nitrates and those carefully stabilized materials.
The Tip Origin of a Shaped Charge Jet*
Authors: Carleone J. , Jameson R. , Chou Pei Chi 
Published: December 2004

AbstractThis study demonstrates that the pex portion of a typical 42° conically lined shaped charge is not being efficiently utilized. In fact, approximately 40% of the liner height at the apex end of the cone does not provide an efficient jet as far as penetration depth is concerned. In this paper, we present an experimental and theoretical study of the liner apex. First, a series of experiments were conducted in which liner apices were filled to various heights to inhibit the collapse of the apex portion of the liner. Next, a one‐dimensional analytical shaped charge model was used to simulate the filled cone experiments. From these experiments and calculations we have determined that approximately 30–40% of the cone height is used to produce a compact tip particle rather than a stretching jet. This indicates that i t may be possible to redesign the apex portion of the liner to achieve a more efficient use of liner height.
Thermal Reactivity of Methylammonium Nitrates
Authors: Jain S. R. , Rao M. V. , Pai Verneker V. R. 
Published: December 2004

AbstractThe reactivity of the mono‐, di‐ and trimethyl‐ammonium nitrates to heat has been studied using differential thermal analysis, thermogravimetry and mass spectral analysis. The decomposition temperature of these compounds increases in the order CH3NH3NO3 > (CH3)2NH2NO3 > (CH3)3NHNO3. The activation energies have been determined employing isothermal decomposition technique. Mass spectrometric investigation shows that the extent of decomposition increases with increasing substitution on the nitrogen atom. Possible reasons for such behaviour have been explored.
The State of the Detonation Products of Solid Explosives
Authors: Hornberg H. 
Published: December 2004

AbstractThe polytropic equation, together with the detonation relations, provides practicable values for all the quantities characterizing the detonation products of solid, high explosives apart from the temperature. Its application, however, is restricted to material at absolute zero, that is to solids possessing purely potential energy. Thus polytropic detonation products have the characteristics of solids although their state of aggregation is gaseous.In fact the polytropic equation can be derived by assuming a solid under an internal, expansive pressure sufficient to break all atomic bonds. In terms of the Debye theory this represents an approximation which is valid in the absence of the thermal energy contribution from atomic vibrations. This requirement is satisfied by the detonation products of solid explosives of sufficiently high density since their heat of detonation is completely absorbed by the breakage of atomic bonds or the sublimation of the atomic lattice.The sublimation process in the course of the reaction also allows the Chapman‐Jouguet temperature of the detonation products to be determined from the equilibrium between the phases. In addition the fracture theory provides material data which assign a metallic character to the polytropic detonation products and indicate that they form a conducting plasma.
Is ammonium perchlorate in composite solid propellant under strain?
Authors: Pai Verneker V. R. , Kishore K. , Prasad G. 
Published: December 2004

AbstractThermal decomposition of ammonium perchlorate‐polystyrene propellant as a function of oxidizer loading has been found to behave in a fashion analogous to the thermal decomposition of ammonium perchlorate as a function of precompression pressure. It has been argued that the above behaviour of the propellant is due to the strain caused by the binder film on ammonium perchlorate contained in the propellant matrix. The presence of strain has been demonstrated independently by x‐ray diffraction peak and infrared peak broadening and strain energy measurements.
Thermal Decomposition of Ammonium Perchlorate containing a polymeric additive
Authors: Thomas T. J. , Nandi U. S. 
Published: December 2004

AbstractThermal decomposition of ammonium perchlorate (AP) containing different concentrations of a polymeric additive such as polyvinyl pyrrolidone (PVP) has been studied by the technique of differential thermal analysis (DTA). The decomposition products have been identified by means of a mass spectrometer. The results of these two experiments suggest strong interaction between AP and PVP in the solid state.
A Photographic Study of the Combustion Zones of burning double base propellant strands
Authors: Eisenreich N. 
Published: December 2004

AbstractThe combustion zones of doublebase propellant strands and their dependence on pressure were studied by different photographic techniques to get new information on the action of ballistic modifiers. Photos of short exposure time were taken from the foam, dark and flame zones. The extinguished burning surface was studied by optical and scanning electron microscopes. A detailed picture on the production of carbonaceous material on the burning surface was obtained.
Performance Optimization of Metallized Solid Propellants
Authors: Swaminathan V. , Rajagopalan S. 
Published: December 2004

AbstractThe object of this paper is to present a method for determining, for a typical metallized solid propellant system, the optimum combination of the reactants so as to arrive at a composition which can yield the maximum specific impulse. A direct approach of this kind for optimization of propellants does not appear to have been attempted so far. The optimization is sought to be carried out by expressing the theoretical specific impulse of the propellant under frozen flow conditions as a function of the different variables involved and maximizing the same, subject to the usual linear and non‐linear constraints of mass balance, mass action, pressure balance, energy conservation and entropy conservation. The gradient projection technique due to Rosen has been adopted for carrying out this optimization. The method was programmed on the IBM 360/Model 44 Computer in FORTRAN IV language and the results of the computations for a typical metallized solid propellant system are presented in the paper. The investigations reveal that the gradient projection technique can be a useful computational device for determining the optimum composition and the corresponding performance parameters of propellant systems containing a large number of reactants and products with or without condensed phases.
A Reappraisal of Silver Fulminate as a detonant
Authors: Collins P. H. , Holloway K. J. 
Published: December 2004

AbstractThe preparation and properties of silver fulminate have been examined to assess its potential for use as a primary explosive. It is an extremely effective detonant but does not appear promising as a stab‐sensitive material. It is concluded that its extreme sensitiveness and the hazards and difficulties associated with its preparation render it unsuitable for military applications. It does find commercial use in the manufacture of toys and crackers when it is normally handled exclusively in small quantities and in the wet state.
The relationship of Impact Sensitivity with Structure of Organic High Explosives. II. Polynitroaromatic explosives
Authors: Kamlet M. J. , Adolph H. G. 
Published: December 2004

AbstractImpact sensitivities of organic high explosives are primarily functions of the rates of the thermal decomposition processes taking place in the temperature regimes generated under the impact hammer. For classes of explosives with similar decomposition mechanisms, there appear to be statistically significant linear relationships (sensitivity/composition trends) between logarithmic 50% impact heights and values OB100, a measure of oxidant balance. In addition, it is shown that polynitroaromatic explosives containing a C‐H linkage alpha to the aromatic ring are more sensitive as a class than explosives lacking such a linkage. These results are consistent with the finding that products of thermal decomposition of TNT indicate a preferred site of inter‐ and intramolecular oxidative attack to be at the alpha C‐H linkage.
The Double Pipe Test for Commercial Explosives I. Description and Results
Authors: Lownds C. M. , du Plessis M. P. 
Published: December 2004

AbstractA new test for commercial explosives called the Double Pipe Test has been devised. A column of explosive is placed in the top pipe, simulating a borehole. This pipe rests on a thick‐walled witness pipe, which is dented by the action of the explosive. The arrangement of explosive and initiator in the top pipe is made to represent as closely as possible the practical use of the explosive. No special skill or instrumentation is needed to conduct the test, and scaling up to large charge diameters is easy. Results presented show that the test is very sensitive to variables such as type of initiator and degree of consolidation of the explosive. These and other aspects of explosive performance which are important in their practical use can readily be studied quantitatively with the Double Pipe Test.
Relationships between Impact Sensitivity and Molecular Electronic Structure
Authors: Mullay John 
Published: December 2004

AbstractA very simple calculational procedure is used to investigate the electronic structure of several classes of organic explosives (polynitroaliphatics with trinitromethyl or fluorodinitromethyl groups, polynitroaromatics, polynitroaliphatic nitramines and aliphatic nitrate esters). The method utilizes a bond electronegativity equalization principle. It is shown that atom charges, bond electronegativities and charge transferred in a bond are all potential indicator quantities for predicting impact sensitivity trends for the various classes. Specifically it is shown that charge transferred to the nitro group through a trigger linkage (CNO2, NNO2, ONO2) can classify and correlate impact sensitivity trends in the compounds studied here. The results also indicate that electronic structure is not sufficient by itself to understand the phenomenon. This work in conjunction with previous work(1) shows that both a global quantity (i.e. related to the whole molecule) and a local quantity (i.e. related to the trigger linkage) are needed to understand impact sensitivity behavior.
Analysis of the Functioning of Bridgewire Igniters based on the fitted wire model
Authors: Prinse W. C. , Leeuw M. W. 
Published: December 2004

AbstractThis paper contains the results of a study concerning the thermoelectrical response of a bridgewire fuze head to a d.c. pulse. The experimental part of the study has been performed using a home‐built, improved version of the Thermal Transient Test. The experimental temperature of the bridgewire fuze head as a function of time and current amplitude is described by means of the “fitted wire model”, an extension of the well‐known Rosenthal model. The experimental results are in excellent agreement with the results obtained with the fitted wire model. On the basis of this fitted wire model and postulating a critical temperature of the bridgewire, induction times and energy and power characteristics can be calculated. Furthermore, the model enables the evaluation of the effects of changes in the model parameters upon the functioning of the bridgewire fuze head.
Ballistic Modification of RDX‐Based CMDB Propellants
Authors: Raman K. V. , Singh H. 
Published: December 2004

AbstractThe effect of lead and copper salts and certain metallic oxides was studied on the burning rates of RDX‐based CMDB propellants in the pressure region 35–105 [kg/cm2]. Lead methylene disalicylate (LMDS), basic copper salicylate (BCS). cobaltic oxide and lead stannate produced higher burning rates by 10%–16%. However, these additives were comparatively more effective with nitramine‐based CMDB propellants than AP‐based CMDB propellants. Fluorides of iron, lead and chromium were ineffective as burning rate catalysts. Inclusion of carbon black along with lead salts or metallic oxide gave only marginally higher burning rates. None of the ballistic modifiers studied produced plateau/mesa effect.
Computations of ESR Coupling Constants in Organic Radicals. II. Nitro derivatives of the phenyl radical
Authors: Hameka H. F. , Seiler F. J. 
Published: December 2004

AbstractWe compute the ESR coupling constants and the geometries of a set of nitro derivatives of the phenyl radical. We consider the three mononitrophenyls, the six dinitrophenyls and 2,4,6‐trinitrophenyl. The computations are based on the use of the Gaussian 82 Program Package with the STO‐3G basis set. There are no experimental data available.
Hazards encountered by firing monergolic liquid gun propellants
Authors: Klingenberg G. , Rockstroh H. 
Published: December 2004

AbstractThe sensitivity and hazard associated with the firing of monergolic liquid gun propellants is described in some detail taking a user oriented point of view. Emphasis is placed on the practical aspects encountered in the ignition and combustion of monopropellants in regenerative gun systems. This analysis is based upon experimental evidence obtained from compression ignition studies, closed bomb work and gun firings.
Dynamic Measurements in Combustible and Detonable Aerosols
Authors: Samirant M. , Smeets G. , Baras Ch. , Royer H. , Oudin L. R. 
Published: December 2004

AbstractWe present all the methods used at the ISL for determining the principal parameters of rapid fuel air aerosol dispersions and of their reactions, i.e. combustion and detonation. In a shock tube or in the free atmosphere. we measure the velocity of the dispersed fuel, the breaking of the droplets, their size distribution and their velocities. The investigation of the thermal variations due to the fuel evaporation allows to obtain the composition of the two‐phase mixture air/combustible gaz – fuel.