bluuebunny/crossref_metadata_2025_split 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

AbstractThe 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

AbstractIn 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

AbstractThe 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

AbstractChemical 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

AbstractNylon 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

AbstractThe 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

AbstractThe 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

AbstractThe 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).
Underwater Blasting Work by an Electromagnetic Firing Method
Authors: Taniguchi K. , Inoue K. , Fukuyama I. 
Published: May 2005

AbstractThere 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

AbstractTo 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

AbstractThe 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

AbstractIn 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

AbstractSimple 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

AbstractThe 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

AbstractA 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

AbstractNew 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

AbstractThe 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

AbstractPotassium 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.
Visible Spectra of Standard Navy Colored Flares
Authors: Webster Henry A. 
Published: May 2005

AbstractThe 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

AbstractIn 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

AbstractShaped‐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

AbstractTime 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

AbstractThe 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

AbstractExtracts 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

AbstractA 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.