bluuebunny/crossref_metadata_2025 huggingface dataset:
The temperature and strain‐rate dependence of mechanical properties in polyoxymethylene
Authors: Plummer C. J. G. , Béguelin Ph. , Kausch H.‐H.
Published: May 2005

The computer aided design approach used in current applications of semicrystalline polyoxymethylene (POM) requires high strain‐rate mechanical data. The primary aim of this work has been to measure the room temperature modulus and tensile strength of injection molded samples of POM of different molecular weights at cross‐head speeds of between 10−5 ms−1. We observe no major transition in bulk mechanical behavior in this range of test speeds, the Young's modulus E, in particular, showing little strain rate dependence. This is rationalized on the basis of tensile tests over a range of temperatures, these indicating room temperature to correspond to the plateau in the E(T) curves (Tg for these materials is taken to be −70°C, and the DSC melting onset occurs at ∼ 170°C).

The tensile strength increases as ∼log(dϵ/dt) and the behavior is found to be highly nonlinear, strains to fail of the order of 1 being observed even at the highest strain rates, depending on the molecular weight. It is believed that the yield stress of th crystalline regions determines the tensile strength above Tg, the higher degree of crystallinity associated with lower molecular weights resulting in a slightly higher tensile strength. Nevertheless, failure is qualitatively brittle, with no necking and relatively little permanent deformation. This behavior is discussed in terms of morphological investigations of the fractured samples by optical and scanning electron microscopy (SEM).

In attempting to relate ultimate failure to the molecular/crystalline structure of the samples, measurements of the critical stress intensity for crack initiation in mode I opening, KIC, as a function of crystallization temperature Tc have been carried out using compact tension specimens machined from injection molded and compression molded plaques. KIC increases with molecular weight and decreases with Tc at low test speeds (in spite of an increase in crystallinity with Tc). This is accounted for in terms of a crack shielding model for crack initiation and of molecular rearrangements occurring during crystallization which lead to a decrease in the effective entanglement density with Tc. The implications of this model are then compared with KIC results over a range of cross‐head speeds and temperatures.
The viscoelastic behavior of microcellular plastics with varying cell size
Authors: Shimbo M. , Baldwin D. F. , Suh N. P.
Published: May 2005

In this study, the viscoelastic behavior of a microcellular plastic was investigated with particular emphasis on the effect of cell size. A poly(ethylene terephthalate) resin containing a polyolefin nucleating agent (CPET) was selected as the test material. In order to investigate the effect of cell size, microcellular CPET samples were produced having a nearly constant density of nucleated cells and a varying cell size. The viscoelastic behavior was investigated using a dynamic mechanical analyzer in tensile mode, and the relationship between viscoelastic behavior and cell size is discussed.
Radical copolymerization of acrylic monomers. IV. Effect of substituents on the radical polymerization and copolymerization of phenyl acrylates
Authors: Román J. San , Madruga E. L. , Del Puerto M. A.
Published: May 2005

The kinetics of radical polymerization of phenyl, ortho‐chlorophenyl, and para‐chlorophenyl acrylates, as well as their copolymerization with methyl methacrylate, have been studied dilatometrically. The results obtained indicate that the overall rate of polymerization is affected by the flexibility of the growing radicals. However, the copolymerization of these monomers with methyl methacrylate gives overall rates rather similar for all three systems, being fundamentally regulated by the formation of reversible π complexes between the donor aromatic rings and the acceptor methacrylic double bonds. Dilatometric methods for the study of the copolymerization reactions have been tested and the corresponding binary bonding frequencies Bij and conversion factors Kij have been calculated for the copolymerization of ortho‐ and para‐chlorophenyl acrylates with methyl methacrylate.
Determination of chemical structures by 1H‐ and 13C‐NMR for thermally degraded linear high density polyethylene
Authors: Kuroki Takeshi , Sawaguchi Takashi , Niikuni Sadayuki , Ikemura Tadashi
Published: May 2005

Chemical structures were determined for polymer residues obtained by thermal degradation of a linear high‐density polyethylene. Terminal methyl, double bonds (terminal vinyl, trans‐vinylene, and vinylidene), and long chain branching were identified by using 1H‐ and 13C‐NMR spectra data. The number of these functional groups per 1000 C was quantified with a relative error of about 10%.
Preparative fractionation of nylon 12 by column elution method and gel permeation chromatography
Authors: Ogawa Toshio , Sakai Masakazu
Published: May 2005

Nylon 12 has a low melting point compared with other commercial products like nylons 6 and 66. Nylon 12 was fractionated by the column elution method at 170.8‐C. The same sample was also fractionated by preparative gel permeation chromatography and the molecular weight distribution of the fractions obtained by these methods was similarly determined. The weight‐average molecular weight of the fractions was also found by the light scattering method. Both fractionation methods separate the sample according to molecular weight. The former, however, had narrower fractions in molecular weight distribution than the latter and it was easy to obtain a large number of fractions. It was also generally superior in practical use.
Response of Single‐Particle Optical Counters to Particles of irregular shape
Authors: Gebhart Josef
Published: May 2005

The response of optical particle counters to nonspherical particles is analyzed theoretically and on the basis of experimental results. Theoretical approximations valid for particle diameters d ≪ λ and d ≫ λ (where λ is the wavelength of light) are used to derive some general predictions about the influence of the particle shape on light scattering. These predictions are compared with experiments on six optical particle counters using nonspherical particles. The instruments differ in the kind of illumination (laser or incandescent light), the mean scattering angle and the receiver aperture. When the particle size is smaller than the wavelength the light‐scattering diameter of a nonspherical particle comes very close to its volume‐equivalent diameter. For irregularly shaped particles larger than the wavelength better conditions than giving a “projected area” response cannot be achieved with an optical arrangement for single‐particle detection.
The Analysis of Dust Cake Structures
Authors: Schmidt Eberhard , Löffler Friedrich
Published: May 2005

The operational characteristics of cake‐forming filter apparatus are strongly influenced by the structure of the dust cake formed. The quantitative evaluation of sectional images of loosely bound filter cake deposits is introduced. First the techniques with which the dust cake is prepared and with which scanning electron micrographs may be obtained are described, together with the subsequent digitization by video and computer equipment. This is followed by a comprehensive description of the evaluation of the digitized images, with special emphasis on the determination of the deposit's porosity and the computation of the particle and pore‐size distributions at selected locations. Finally, results derived from a true filter cake are presented.
Particle Sizing by Photon Correlation Spectroscopy. Part II: Average values
Authors: Finsy Robert , De Jaeger Nicolas
Published: May 2005

The average values of the diameters and the diffusion coefficients of non‐interacting homogeneous spherical particles as obtained with photon correlation spectroscopy are reviewed. In general, the average diffusion coefficients calculated from the first cumulant can be identified as intensity averages, while the average particle diameters are harmonic intensity averages. For particles with linear dimensions that are small compared to the wavelength of light, the intensity averages can be identified as z‐averages for the diffusion coefficient and as harmonic z‐averages for the diameter. For larger particles the intensity averages are, however, different from the z‐averages and are dependent on the material examined (relative refractive index) and on the experimental equipment used (laser wavelength and state of polarization and scattering angle).
The Physically Relevant Parameter Space of the Nukiyama‐Tanasawa distribution function
Authors: Paloposki Tuomas
Published: May 2005

The range of the parameters of the Nukiyama‐Tanasawa distribution function was analysed, leading to the identification of the physically relevant parameter space. The analysis was also applied to the Rosin‐Rammler distribution function.
Underwater Blasting Work by an Electromagnetic Firing Method
Authors: Taniguchi K. , Inoue K. , Fukuyama I.
Published: May 2005

There are many difficulties and dangers when carrying out underwater blasting in a rapid stream. The electromagnetic firing method is a special type of the remote control firing method and has a distinct advantage to the underwater blasting. The principle of this method is based on electromagnetic phenomena, the induced electromotive force by the coil which is set into the electromagnetic field is applied to fire the detonation cap.

In this paper, the authors discuss the fundamental theory of the electromagnetic field caused by the exciting loop, and the effect of the conductive medium. As an example, they present the procedure and results of an actual underwater blasting work which is the first application of this technique.
The effect of vacuum and radiation on solid propellant properties
Authors: Unnikrishnan K. , Pandureng L. P. , Krishnamurthy V. N.
Published: May 2005

To understand the changes occurring in solid propellants on storage under space environments, the effect of vacuum and radiation on different propellants were studied. It was found that propellants lost weight on vacuum storage and that the rate and extent of weight loss depended upon the plasticizer content, the exposed surface area and the vacuum level. Mechanical properties and burning rates were practically unaffected and the effect on thermal decomposition was marginal. On the other hand, irradiation with gamma rays resulted in a drastic deterioration of mechanical properties and in a large increase in the rate of thermal decomposition at 225 °C. Radiation had no effect on burning rates.
Performance Characteristics of a Laser Initiated Microdetonator
Authors: Yang L. C.
Published: May 2005

The test results of 320 units of a laser initiated microdetonator are summarized. The commercially fabricated units used a lead styphnate/lead azide/HMX (1 mg/17.5 mg/13.5 mg) explosive train design contained in a miniature aluminum can that was capped with a glass‐metal seal window. The test parameters were the laser energy, temperature, laser pulse duration, laser wavelength and nuclear radiation (5 × 106 rad of 1 MeV gamma rays). The performance parameters were the laser energy for ignition and the actuation response time.
Mach Reflection in Condensed Explosives
Authors: Krishnan S. , Brochet C. , Chéret R.
Published: May 2005

In an experimental setup two transparent condensed explosives of different detonation velocities are coaxially arranged to give Mach reflection in the low speed explosive (overdriven detonation). Due to the transparent characteristic of the explosive, this setup, with a suitable streak camera, is shown to give the facility of continuously recording the phenomenon of Mach reflection before as well as after its formation. The important characteristics of Mach reflection, viz., triple point growth angle, Mach‐disc configuration and its dimension, and propagation velocity can now be accurately and continuously measured; also the information on the transients before the formation of Mach reflection is made available. The possibility of generating these data continuously with the improved accuracy will help in better understanding of Mach‐reflection phenomenon.
Blast Waves in Free Air
Authors: Held M.
Published: May 2005

Simple equations are given which can be used for calculating the approximate values of peak overpressure and positive phase impulse of blast waves generated by the detonation of military high explosive charges in the free atmosphere. To the practitioner, these equations may be useful in the quick and simple design of protective systems, or in calculating the amount of explosive required to achieve a certain desired effect. Moreover, an outline is given of the derivation of simple equations for the damaging effect of blast waves as a function of distance and charge weight. A useful formula, which had been given by Westine, encompasses the following three main causes of a damaging effect:

peak overpressure, if the blast duration is long as compared to the natural vibration period of the target structure;

pressure impulse, if the blast duration is short as compared to the natural vibration period of the target structure;

product of peak overpressure multiplied by impulse in the intermediate range, i.e., if the duration of the pressure pulse is comparable to the natural vibration period of the target structure.
Performance Properties of Commercial Explosives
Authors: Johnson J. N. , Mader C. L. , Goldstein S.
Published: May 2005

The aquarium test is a proven means of obtaining nonidial performance property data for commercial blasting agents. Optical data on the detonation velocity, shock wave in water, and expansion rate of the pipe enclosing the detonation products (in combination with the equilibrium thermodynamic chemistry code BKW) give the C‐J state and degree of chemical reaction at the detonation front, as well as information on additional chemical reaction that occurs as the detonation products expand. Specific explosive systems that are studied are ammonium nitrate‐fuel oil mixture (ANFO), aluminized ANFO, flaked trinitrotoluene (TNT), and several other commercial products in 10‐cm‐diam and 20‐cm‐diam pipes of Plexiglas and clay. Experimental shock pressure data are obtained with lithium niobate transducers placed in the water surrounding the explosive charge. These data show that the addition of ∼ 100‐μm aluminum particles to ANFO significantly increases the initial peak shock pressure delivered to the surrounding medium. Peak shock pressures in the water, calculated from the shock‐wave orientation, are also useful in comparing performance properties of various commercial explosives.
Testing of a New Concept for the Storage of Granular Propellant
Authors: Frauenfelder R.
Published: May 2005

A new concept for the storage of granular propellants envisages storage buildings that consist of a number of storage rooms arranged side by side, and which avail of a common entrance room. In order to examine the possible spreading of fire from one storage room to another during the deflagration of a propellant charge in one of the rooms, a number of deflagrations have been conducted in a experimental building which consists of three adjacent storage rooms and one common entrance room. The building itself is equipped with a valve‐type roof whose corrugated sections pivot on one side. The steel doors leading from the entrance room into the storage rooms are of the lifting‐type and are fitted with a dual labyrinth seal and an interspace ventilation.

The middle storage room was used for 13 deflagrations of propellant charges ranging from 500 kg to 4500 kg. Four types of propellants of differing brisance were employed for the task. The measurements of the effects caused by deflagration upon the two neighbouring rooms and the surroundings of the building itself entailed considerable technical efforts. In virtue of the extensive test results the new storage concept is assessed as being safe.
Electrostatic charge measurements on initiators and explosive powders
Authors: Lokre V. L. , Borkar D. M. , Bankar L. K.
Published: May 2005

New mechanical handling system for simulating the handling of explosive powders in the explosives factories have been designed, developed and successfully used for measurements of electrostatic charges under actual working conditions. The results of some of the important initiators using conventional friction/rolling method have been also discussed. The observations indicate that barium styphnate (red) shows positive charge whereas barium styphnate (yellow) shows negative charge.
Smoke Generators. II. The ignition of pyrotechnic white smoke compositions containing hexachlorethane, silumin and zinc oxide using a heated metal surface
Authors: Hartley F. R. , Murray S. G. , Williams M. R.
Published: May 2005

The ignition by hot plate of a series of smoke generators containing hexachloroethane, silumin and zinc oxide, has been investigated. Pellets of hexachloroethane/silumin of 1.27 cm and 1.91 cm diameter show no significant difference in ease of ignition. This mixture showed an increase in the minimum temperature of ignition at pressing loads below 7.9×106 kg/m2. The addition of zinc oxide progressively decreased the chance of ignition within short heating times (less than 100 seconds), but did not significantly alter the minimum temperature of ignition.
Potassium Benzoate for Pyrotechnic Whistling Compositions
Authors: Whelan D. J. , Elischer P. P.
Published: May 2005

Potassium benzoate is one of the ingredients in the formulation of SR 136 Whistling Composition, but some ambiguity exists in the chemical literature as to its composition. In this investigation, it was established that potassium benzoate precipitates from aqueous alcohol and crystallizes from water as colourless plates, it does not contain water of crystallization and it does not appear to take up water from its environment. Its DSC trace over the temperature range 310 K‐730 K consists of a single endotherm occurring near 714 K, which is probably due to melting, the heat of fusion being ca. 213 J/g. It can be prepared from stoichiometric amounts of benzoic acid and either potassium hydroxide or potassium bicarbonate.
Procedure for Measuring the Response Time of Mechanical Impact Fuzes for Projectiles
Authors: Held M. , Giovanelli H. , Sögtrop G.
Published: May 2005

This paper describes the measuring equipment and procedure for determining the response time of projectile impact fuzes. Examples are given of response times of typical mechanical projectile fuzes which were determined using the measuring equipment and procedure.
Visible Spectra of Standard Navy Colored Flares
Authors: Webster Henry A.
Published: May 2005

The visible spectra, color data and output powers from standard U.S. Navy red, green and yellow signal flares are presented. The spectra were taken under essentially identical conditions on actual inservice U.S. Navy devices. The dominant emissions accounting for the output power in the flares are from the molecular bands of the alkaline earth oxides, hydroxides and chlorides in the red and green flares and from atomic sodium in the yellow flare.
Determination of Fume State Parameters from Expansion Measurements of Metal Tubes
Authors: Hornberg H.
Published: May 2005

In cylinder tests, the time progression of the radial deflection of metal tubes as a result of fume (detonation products) expansion are measured. The parameters of the relevant, analytical curves obtained can be determined via a fitting process, from which the expansion velocities of the cylinder wall are obtained through differentiation. In conjunction with conservation propositions for the gas flow in cylinders of varying cross‐sections, the course of an expansion process can be calculated iteratively. By taking the JWL curve representation as a basis, the parameters in this context may also be determined by fitting. In this way, the basis for calculation of all types of terminal ballistic data or a splinter picture of the cylinder wall can be given.

In the tests, a total of 17 explosives were included with their initial data known from literature, in order to obtain in this way a comparison with those evaluation procedures for cylinder tests which have been in use up to present.
Recent Developments in Shaped Charge Technology
Authors: Chou P. C. , Flis W. J.
Published: May 2005

Shaped‐charge principles, including analytical work, computer‐code simulations, and experimental results, are reviewed. It is assumed that the reader has a basic understanding of the functioning of shaped charges, and emphasizes developments in recent years. The survey is divided into four sections: Liner Collapse, Jet Formation, Jet Breakup, and Target Penetration. Only traditional shaped charges are covered; kinetic‐energy penetrators and self‐forging‐fragment warheads are not included. Ninety‐nine references are cited.
Time Resolved Pressure Measurement of the Initiation in Gap Test Experiments
Authors: Hollenberg K.
Published: May 2005

Time resolved measurement of shock pressures in high explosives is possible with inexpensive composite carbon resistors. These resistors are embedded plane to the surface of a Plexiglas slab fixed at the end of the explosive. This configuration was used with gap test experiments with a 10 g donor charge. No initiation delay is measured in Seismoplast I (plastic PETN) up to a gap height of 10 mm PMMA (Plexiglas) due to the time resolution of the measuring system. From 10 mm to 22.5 mm gap height distances for detonation development up to 25 mm are found. For even greater gap heights a shock wave with decreasing amplitude occurs. The detonation development can be explained by the measured structure of the shock waves. Behind a first shock front with nearly constant pressure a second front propagates with increasing pressure which at last catches up with the first and then the pressure increases further up to the Chapman‐Jouguet pressure of 160 kbar. At a gap height of 25 mm a stationary shock wave configuration with amplitudes of 20 kbar and 30 kbar was observed.
Discussion of the Experimental Findings from the initiation of covered, but unconfined high explosive charges with shaped charge jets
Authors: Held M.
Published: May 2005

The results of experiments on the initiation of covered, but unconfined high explosive charges with shaped charge jets from Chick and Hatt, which have been diagnosed by the flash X‐ray technique, as well as the author's own experiments in which the build‐up distances and the run‐up times have been recorded by means of a rotating‐mirror camera in the framing and streak modes, are analyzed and explained in detail in this paper. Build‐up distances and run‐up times versus the residual jet velocity, or versus the dynamic pressure, are in fairly good agreement, despite the somewhat different shaped charges and acceptor charges that have been used in the two approaches.

The greater initiability of an acceptor charge behind a barrier, but with an air gap between, is attributed less to a precursor shock that desensitizes the high explosive charge which is in contact with a barrier, but rather to the higher velocity of the free shaped charge jet and, particularly, to the area loading on a high explosive charge with an air gap in front.
LC/MS studies of Ethyl Centralite Stabilized Propellants
Authors: Druet L. , Angers J.
Published: May 2005

Extracts of the stabilizer ethyl centralite and its derivatives in a series of aged gun and mortar propellants were investigated by combined high performance liquid chromatography/mass spectrometry (LC/MS). The HPLC retention times and the chemical ionization mass spectra obtained allowed positive identification of several products and made it possible to construct concentration profiles as a function of aging time. These results are useful for implementation of modern methods into stability surveillance programs for gun and mortar propellants.
Derivatives of Ethyl Centralite in Australian gun propellants
Authors: Curtis N. J. , Berry P.
Published: May 2005

A new high performance liquid chromatography method has been developed for the analysis of ethyl centralite (EC) and its derivatives found in Australian gun propellants. The following derivatives were detected at > 0.05% level: 2‐nitro EC, 4‐nitro EC. 2,4′‐dinitro EC, 4,4′‐dinitro EC, N‐ethyl‐N‐nitrosoaniline and N‐ethyl‐4‐nitro‐N‐nitrosoaniline. Several minor derivatives were also identified. The ratio of monoaromatic to urea products increased as a function of EC content and also with aging at 80°C. Para derivatives were favoured over ortho substitution.
Combustion of Black Powder. Part 1: Thermo‐analytical studies
Authors: Hussain G. , Rees G. J.
Published: May 2005

An experimental programme is described, in which a number of thermo‐analytical techniques, differential scanning calorimetry (DSC), thermogravimetry (TG and DTG) are applied to investigate the combustion of black powder. The primary aim has been to investigate, and determine qualitatively and quantitatively, the nature of the solid products of combustion. Additionally, standard analytical techniques were applied, to a chemical analysis of the solid products, resulting from the electric arcignition of a sample of black‐powder, under ambient, open air conditions. The solid products formed 33% by weight of the unburned black powder, consisting of K2SO4 (15%), K2CO3 (11.5%) and small amounts of KNO3 and KNO2. The DSC, TG and DTG analyses suggest a mechanism for the combustion, based on phase changes and transition stages of sulfur and KNO3, and their interaction with charcoal.
FTIR spectroscopic study on the Interaction between Ammonium Perchlorate and Bonding Agents
Authors: Hori Keiichi , Iwama A. , Fukuda Takaaki
Published: May 2005

The interaction between ammonium perchlorate and bonding agents has been investigated by means of Fourier transform infrared spectroscopy (FTIR). The analysis results endorse that the interfacial bonding force is hydrogen bond for aziridine type compounds and ionic bond for alkylene polyamine derivatives, respectively.
Detonation Behavior of Emulsion Explosives
Authors: Lee Jaimin , Persson Per‐Anders
Published: May 2005

Detonation behavior of emulsion explosives sensitized by glass microballoons was studied. The detonation velocity and the failure diameter of emulsion explosives at various densities were measured in two charge configurations: cylindrical charges by ionization pins and conical charges by ionization pins and continuous resistance probes. The effect of microballoon size on detonation velocity and failure diameter was also determined.

The behavior of emulsion explosives showed a marked difference from that of other high explosives; the detonation velocity reached its maximum far below the maximum density; the failure diameter increased with increasing density. The detonation velocity extrapolated to infinite diameter deviated increasingly from the predictions of the BKW code and of the Kamlet method as the initial density decreased. Diameter effect curves were downward concave and the diameter effect became more pronounced with increasing density. The temperature had a negligibie effect on the detonation velocity. At a given density, the detonation velocity increased linearly with decreasing microballoon size. The increase in detonation velocity was obscured at low densities by the increasing weight of glass added. I he failure diameter had a linear relationship with the spacing between microballoons.
Characteristics of Porous Ammonium Perchlorate and propellants containing same
Authors: Chang Fang‐Mo , Huang Chen‐Chia , Yeh Tsao‐Fa , Liu Chao‐Shih , Leu An‐Lu
Published: May 2005

Porous ammonium perchlorate (PAP) was prepared by a successfully developed fluidization process at 230°C. The geometric structure of manufactured PAP was characterized by means of a scanning electron microscope (SEM). The physical and mechanical properties of composite propellans containing PAP were also determined. Owing to the diffusion of binder into pores of PAP, the elongation of propellants decreased.
Studies on octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) polymorphism
Authors: Achuthan C. P. , Jose C. I.
Published: May 2005

Various methods of preparation of the different polymorphs of HMX have been evaluated. Infrared and Raman spectra have been used to differentiate the polymorphs and understand their conformational behaviour. Possible conformation of the γ form has been suggested.
Fragment Mass Distribution of “Secondary Fragments”
Authors: Held Manfred
Published: May 2005

An analysis of the secondary fragments emerging from a target plate has shown that their mass distribution fits excellently to a formula established earlier by the author. This applies equally well to the secondary fragments of an explosive‐formed fragment from a multi‐P warhead, to those from the warhead's structural casing. and even to the fragments from the target plate itself, as well as to the sum of all of these 3 types of fragements. The correlation coefficient for the two constant parameters governing this formula (namely, the scaling factor B and the form factor λ) is always better than 0.99, when an optimum total mass Mo is southt and inserted, and when the first, large fragements are not included in the consideration, which means when one or two measured points are negiected. For secondary fragements, the form factor λ in the mass distribution is close to 1/2 = 0.5, whereas for the natural fragments of HE projectiles it is in the order of 2/3. namely, from 0.6 to 0.8.
Predicting the density distribution in pressed charges using the finite element method
Authors: Essig W. , Osswald T. A. , Saßmannshausen U.
Published: May 2005

High performance shaped charges require a perfect rotational symmetry and material homogenity. In order to obtain the desired geometry of a detonation wave the density distribution of the explosive, inside such a charge, must meet certain specifications and must be symmetric. This paper presents a finite element simulation of the pressing process of shaped charges implementing a recently developed material model. The calculated result agree well analytical solutions and experiments.
Effect of Boron Particle Surface Coating on combustion of solid propellants for ducted rockets
Authors: Liu Tai‐Kang , Luh Song‐Ping , Perng Huey‐Cherng
Published: May 2005

Combustion behavior of B/MA/AP/HTPB fuel rich propellants containing different coated boron particles was studied with several diagnostic facilities such as windowed strand burner, CO2 laser ignition facility, rapid depressurization quenched device, thermal analyzer and micromotor static test. Materials selected for boron coating include LiF, Viton A and silane. Baseline propellant containing uncoated boron was also studied for comparison Results from windowed strand burner and static test show that LiF‐propellant exhibits the most remarkable overall behavior. Ignition study indicates that LiF‐propellant gives the shortest while Viton A‐propellant gives the longest ignition time under the same heat flux. Moreover, mechanisms were proposed to elucidate the experimental results and the observed combustion phenomena.
Energetic Solid Fuels for Ducted Rockets (II)
Authors: Kubota N. , Yano Y. , Miyata K. , Kuwahara T. , Mitsuno M. , Nakagawa I.
Published: May 2005

The combustion characteristics of variable‐flow ducted rockets were evaluated in order to obtain optimum design parameters of the gas generators. The energetic solid fuels used for the gas generators were glycidyl azide polymer (GAP) with burning rate catalysts. The burning rate of GAP based energetic fuels was much higher than that of composite and double‐base based fuel‐rich propellants. The pressure exponent of the burning rate was high enough to obtain a wide range of variable‐flow rat. Two types of combustion test were conducted: a semi‐free jet and a direct connect flow. The pressure‐time response in the primary combustor obtained by the use of a throttable nozzle was evaluated.
The energy and pressure exponent of composite modified double‐base propellant
Authors: Zhulin Hou , Zeng‐guo Feng , Enpu Wang , Panming Han
Published: May 2005

The paper describes an analysis on the energy and pressure exponents of composite modified double‐base (CMDB) propellants. The evaluation of the energy was conducted by means of a thermodynami‐ cal program. Propellant burning rates were determined by the strand burner method. In the AP‐based composition, the energy is enhanced and the pressure exponent reduced with increasing AP content. When AP is partially or entirely replaced by the nitramines HMX or RDX, Isp is improved, and the pressure exponent is inevitably increased. A mixture of lead salicylate or lead o‐amino benzoate and copper 2,4‐ or 3,5‐dihydroxy benzoate produces a remarkable effect on the burning nature of the CMDB propellant. It was noted that the pressure exponent decreases from 0.66 to 0.48 with lead and copper salts added at 3.0% in AP‐Al, 0.82 to 0.60 at 2.0% in RDX‐Al and 0.72 to 0.54 at 2.5% in RDX‐AP‐Al compositions, respectively.
Thermal decomposition of energetic materials. 55. Metal Complexes of Diamioglyoxime as Potential Burn Rate Modifiers in composite propellants
Authors: Stoner C. E. , Haggerty B. S. , Rheingold A. L. , Brill T. B.
Published: May 2005

Metal complexes having the potential to modify the burn rate of rocket propellants are described. These are the diaminoglyoxime (DAG) complexes: Co(DAG–H)2·DAG, Cu(DAG–H)2·DAG, Ni(DAG–H)2 and Pd(DAG–H)2. The thermal decomposition was characterized by DSC, TGA and IR spectroscopy at a heating rate of 5°C/min, and by fast thermolysis/FTIR spectroscopy at 100–250°C/s. The M(DAG–H)2 complexes are more thermally stable than M(DAG–H)2·DAG. However, all of the compounds produce highly thermally stable residues which would be expected to retard the heat and mass transfer at a burning surface. The residues most closely resemble coordination complexes of the metal and polymeric cyclic azine compounds. The crystal and molecular structure of the previously unreported complex Ni(DAG–H)2·HCL is described.
Molecular orbital studies of the thermal decomposition mechanism of dimethylnitramine
Authors: Ling Yue , Tang Ze‐Hua , Xiao He‐Ming
Published: May 2005

The electronic structures of dimethylnitramine (DMNA) were calculated using ab initio Gaussian 80 program at the Hartree‐Fock level with STO‐3G and STO‐4‐21G basis set, respectively. The Mulliken bond order of the NNO2 bond is the least one in comparision with those of the other bonds in the DMNA molecule. Two potential energy curves along the NN bond splitting pathway (RNN) were obtained using MINDO/3 and MNDO methods, respectively. These curves have the same trend and are qualitatively consistent with the results obtained from the thermolysis of nitromethane (CH3NO2). It was found that the frontier MO levels and the net charges of groups are changed with RNN distance. The products of thermal decomposition and the energy changes were calculated by MINDO/3 method and are discussed in this paper.
LOVA Gun Propellants with GAP Binder
Authors: Schedlbauer Fritz
Published: May 2005

First results will be presented in the field of LOVA gun propellants with polyglycidylazide‐binder system. Theoretical calculations and experimental investigations were carried out to get informations about the ballistic behavior of this type of gun propellant. Chemical stability and mechanical properties were also determined. In addition, the bullet impact test was performed. All these dta were compared with those of nitramine‐gun propellants based on HTPB.
Aging Behavior of Propellants investigated by heat generation, stabilizer consumption, and molar mass degradation
Authors: Bohn Manfred A. , Volk Fred
Published: May 2005

Four double‐base rocket propellants and a single‐base gun propellant were tested to find out stabilizer consumption molar mass degradation, and heat generation between 50 °C and 90 °C and between 40 °C and 110 °C, respectively. Stabilizer depletion was measured by high performance liquid chromatography (HPLC), molar mass degradation by gel permeation chromatography (GPC), and heat generation by microcalorimetry. The conditioning times at different temperatures were determined with one of the rocket propellants, and the influence of the long‐term storage on heat generation at 60 °C for 2191 dys was investigated. A correlated experiment between stabilizer consumption and heat generation showed that heat production does not increase substantially until the stabilizer has been consumed almost completely. The experimental data of molar mass degradation are described by a kinetic model based on statistical chain scission, and the stabilizer decrease by a first order reaction. For the gun propellant the Arrhenius plots of the reaction rate constants show two temperatures of teh stabilizer consumption, molar mass degradation and heat generation were determined.
The Flow Characteristics of High Explosives
Authors: Akhavan J. , Welsh L. J.
Published: May 2005

A comparative study of flow properties of the explosive compound RDX is presented. The results were used to identify desirable free‐flowing characteristics in the powders. Various static and free‐flowing tests were conducted on the explosive powders. The results suggest that flow properties of the RDX powders tested were not influenced by particle size and surface roughness. However density, moisture content and cohesive strength between the particles had some effect on the flow properties. An increase in moisture content and cohesive strength of the particles reduced the flow rate. Whereas an increase in bluk density of the powders increased the flow rate.
Urethane Reaction Mechanism on the Amorphous Boron Surface in GAP propellants
Authors: Oyumi Yoshio , Nakashita Goro
Published: May 2005

Thermal analysis and FT‐IR spectrometry were used to characterize the urethane reaction mechanism of polyglycidyl azide (GAP) propellants with powdered amorphous boron. The amorphous boron added GAP propellant with trimethylol propane (TMP) vigorously gassed of during the cure process and did not complete its urethane reaction. Although it was curable by excess amount of isocyanates, voids or bubbles were trapped inside the propellant grain. Since the powdered amorphous boron was relatively hygroscopic compared to other crystalline metal powders, it might contain boron surface impurities, namely, water, boric acid, and/or boron oxide which disturbed the urethane reaction. TMP was also relatively hygroscopic and played an interesting role on the propellant processing, which was used for cross‐link and surface treatment agent of powdered amorphous boron.
An Improved Simple Method of Deducing JWL Parameters from cylinder expansion test
Authors: Lan I‐Feng , Hung Sheng‐Chih , Chen Chun‐Yu , Niu Yih‐Ming , Shiuan Jonq‐Hwa
Published: May 2005

A simple method which is much simpler than, while retaining the same degree of accuracy, as that of a large computer hydrocode has been developed for deducing the JWL equation of state (EOS) of high explosive detonation products from the cylinder expansion test.

The radial expansion history of metal tube, which is recorded by the streak camera, is expressed as an appropriate fitting function with the aid of a nonlinear curve fitting procedure. The measured data with respect to Eulerian coordinate are transformed to that in Lagrangian coordinate so that the p‐V relation of detonation products may be obtained from the differentiation of fitting function and equations of conservation law. Metal strength is also taken into consideration to reduce the deviation at the lower pressure region. JWL parameters are acquired through the p‐V relations by another nonlinear curve fitting procedure.

The computed results for Comp‐B, TNT, HMX, PBX‐9404 and nitromethane, which are in good agreement with Lawrence Livermore National Laboratory (LLNL) data, are listed for comparison with other procedures in literature which have been in use so far.
Quantitative Measurement of Propellant Stabilizers with tlc and liquid‐crystalline method of visualization
Authors: Miszczak Maciej , Bladek Jan
Published: May 2005

Basic compounds of propellants, nitrate esters decompose forming nitrogen oxides as the catalytic products. To inhibit further decomposition, stabilizer reacts with nitrogen oxides, and finally non‐catalytic products are formed, so autocatalytic decomposition is minimized. In this way, chemical stability of propellant increases, but the content of stabilizer decreases.

In this paper, the possibility of quantitative analysis of the weight loss of propellant stabilizer using the TLC method and the liquid crystal method of visualization is presented. The advantages of solid phase extraction (SPE) application in such analysis are also shown.
An Extension to the Critical Energy Criterion used to predict shock initiation thresholds
Authors: James H. R.
Published: May 2005

It has long been appreciated that the critical energy (Ec) criterion, developed by Walker and Wasley(1), has been limited in both the pressure range over which it applies(2), and in the number of explosive formulations which appear to obey it(3). The addition of a specific energy “cut‐off” to the criterion enables it to be applied to explosives previously considered to lie outside the original criterion, and to extend the range of impacts covered by the criterion in explosives which obey Ec within certain pressure limits. The new criterion appears particularly applicable to cast PBX formulations and insensitive high explosives such as TATB.
PBX 9502 Products Equation of State
Authors: Tang P. K.
Published: May 2005

We constructed a Jones‐Wilkins‐Lee (JWL) equation of state (EOS) for the PBX 9502 detonation products based on a standard one by lowering the Chapman‐Jouguet (CJ) pressure. We found that a slow component exists in the chemical reaction rate, and the global hydrodynamic behavior as exhibited by the standard EOS reflects such an effect. By reducing the CJ pressure, we effectively remove the contribution of the slow reaction from the standard EOS, and the new EOS should represent the detonation products better. In conjunction with a reactive burn model which includes a slow component, the products EOS performs better than the standard EOS.
Phase Transitions and Lattice Dynamics of Ammonium Nitrate
Authors: Herrmann Michael J. , Engel Walter
Published: May 2005

Advanced evaluation techniques as Rietveld refinement applied to series of temperature resolved X‐ray diffraction measurements, provide an improved insight into the lattice dynamics. The transition paths of ammonium nitrate are clearly defined and coexisting phases are quantitatively determined. The curves for the elementary cell parameters of the different phases as a function of temperature exhibit hitherto unknown details and elucidate expansion and transition mechanisms. They are used for the calculation of the volume changes during the transitions and the volumetric and linear expansion coefficients.
Disposal of Energetic Materials by Alkaline Pressure Hydrolysis and combined techniques
Authors: Bunte Gudrun , Krause Horst H. , Hirth Thomas
Published: May 2005

Due to the reduction of armament and especially due to the German reunification we are met by the objective of the disposal of energetic materials. Environmentally friendly disposal methods available for the different propellants, explosives and pyrotechnics are urgently needed. The main component of gun and rocket propellants is the energetic polymer nitrocellulose. One method to dispose nitrocellulose containing propellants is the combination of rapid chemical destruction by pressure hydrolysis and the biological degradation of the reaction mixture. The study describes the results of pressure hydrolysis of different gun and rocket propellants. Under alkaline conditions (propellant to NaOH ratio 2.3:1; reaction temperature 150 °C; pressure below 30 bar) biological degradable reaction products were formed. The main products in the liquid phase were simple mono‐ and dicarboxylic acids. Dependent on the reaction conditions 30–50 % of the nitrogen content of the propellants was transformed to nitrite and nitrate. The gaseous nitrogen containing products were N2 (16–46 %), N2O (2–23 %), NOx (0–5 %). Overall 40%–60% of the propellant nitrogen was transformed to gaseous products. In the solid residues a nitrogen content between 2 % and 9 % was found. The residues were mostly due to additives used in propellant manufacturing. In the case of nitrocellulose pressure hydrolysis below 30 bar and reaction temperature about 150 °C are sufficient.
Formation of Particles of Explosives with Supercritical Fluids
Authors: Teipel Ulrich , Förter‐Barth Ulrich , Gerber Peter , Krause Horst H.
Published: May 2005

The particle properties of components of explosives and propellants, i.e. the particle size, the particle size distribution and the particle shape, are very important. Especially with regard to insensitive explosives, the formation of crystals without spots, i.e. free of solvent inclusions, is aspired. New processes, taking advantage of the special characteristics of high‐compressed respectively supercritical fluids, offer many possibilities to influence the properties of solid particles. For the RESS process (Rapid Expansion of Supercritical Solutions), the formation of particles results from the rapid expansion of a loaded supercritical fluid. The GAS process (Gas Anti‐Solvent) uses a high‐compressed fluid as anti‐solvent to lower the solvent power of a common solvent and thus to recrystallize the solid. In this report, the different processes to form particles of explosives and propellants with supercritical fluids are explained, and the first results are presented.
Combustion and Sensitivity Characteristics of Mg/TF Pyrolants
Authors: Kuwahara T. , Matsuo S. , Shinozaki N.
Published: May 2005

Burning rate characteristics and sensitivity characteristics of energetic mixtures composed of metal particles and oxidizers, the so called ‘pyrolants’, were studied experimentally. The pyrolants tested were made of various particle sizes of magnesium (Mg) and polytetrafluoroethylene (TF). Mg/TF pyrolant produces high combustion flame temperature, so it is used as heat sources and igniter pyrolants. The maximum flame temperature (Tf) is 3271 K at 0.1 MPa, and 3483 K at 1 MPa. These values are obtained when Mg concentration is 30%. When the Mg concentrations are less than 50% the pyrolants are not able to burn stably at one atmosphere. The burning rate increases with increasing the concentration of Mg and decreases with increasing the mean diameter of Mg particles at constant pressure. Explosive energy evaluated with drop hammer test decreased with increasing burning rate, so there is strong relationship between burning rate and explosive energy.
The Electrothermal Enhancement of Propellant Burning by Plasma Injection
Authors: Proud W. G. , Bourne N. K.
Published: May 2005

A series of experimental demonstrations of plasma injection into a burning propellant interface is presented. The propellant is a nitro‐guanidine based material in the form of a right cylinder with a bore along its central axis. It is ignited by a hot‐wire system and, when a pre‐set pressure is achieved, a second wire is exploded using a high‐voltage capacitor discharge circuit. The second wire forms a plasma, precisely at, or well away from the burning interface. Comparing the pressure histories from these different geometries allows the effect of increased burning rate to be separated from Joule heating of the product gases. Analysis of these histories shows a pressure increase over that caused by Joule heating of the products.