bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heterogeneous grafting on polymers containing chlorine: Grafting of amide groups in water suspension and the reactivity of the new polymer towards epoxy resins
Authors: Levin G. , Nae H. N. 
Published: May 2005

AbstractHeterogeneous grafting on polyvinylchloride suspended in water was carried out using N‐butyl‐3‐mercaptopropionamide as nucleophile. Over 50% graft was obtained by using a small amount of solvent as a swelling agent and tricapryl methyl ammonium chloride as a phase transfer catalyst. Elemental analysis of the grafted polymer shows that the chlorine displaced from the polymers is replaced by the thio‐amide group. The above conclusion is supported by NMR and IR analysis. The kinetics of the chlorine displacement from PVC by the thio amide group obeys the Shell progressive mechanism. The rate at which an individual spherical particle reacts depends on the diffusion through the reacted layer. The grafted polymer is soluble in tetrahydrofuran or nitrobenzene. The films obtained from the grafted material are brittle due to excessive internal hydrogen bonding. The electrostatic charge which is a characteristic surface phenomena in PVC is diminished in the grafted polymer which may be due to the existence of the amide group near the surface. The amide groups attached to the side chains on the polymer may participate in various reactions, e.g., with epoxy resins. IR analysis of the cured film indicates the disappearance of the oxiran band at 913 cm−1 and an increase in the hydroxyl band around 3300 cm−1. Thus, grafting of amide groups on PVC enables us to further modify PVC by epoxy resins.
The crosslinking of epoxy resins at interfaces. II. At an aromatic polyamide surface
Authors: Garton Andrew , Daly John H. 
Published: May 2005

AbstractThe first 200–400 nm of crosslinked epoxy resin adjacent to an aromatic polyamide (aramid) surface were characterized by internal reflection spectroscopy (IRS) using an aramid‐coated IRS element. The crosslinking kinetics and final crosslinked state of an anhydride‐cured epoxy resin were strongly affected by the aramid surface, which produced a localized increase in the rate of anhydride consumption and a decrease in the yield of ester products. An aromatic amine‐cured epoxy resin was less affected by the aramid surface. Unidirectional aramid fiber:epoxy composites were examined by dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC). The chemical changes detected spectroscopically were shown to correlate with mechanical and thermal transition data obtained by DMA and DSC. These results are rationalized on the basis of the effect of absorbed moisture in the aramid on the crosslinking chemistry.
Polymerization of oriented monomers. VIII. Polymerization of allyl and diallyl vesicle‐forming quaternary ammonium salts
Authors: Babilis D. , Dais Photis , Margaritis L. H. , Paleos C. M. 
Published: May 2005

AbstractThe synthesis of two novel allyl and diallyl vesicle‐forming quaternary ammonium salts is reported. The topochemical polymerization of these monomeric vesicles to their polymerized counterparts was performed by γ‐ray irradiation and the observed differentiation in polymerization rates of allyl and diallyl monomers was attributed to different polymerization mechanisms. It was further established that only polymerized vesicles which result from diallyl monomer retain the structure of the monomeric vesicles and exhibit simultaneously higher stability.
Solid‐state thermal polymerization of the heterocyclic HC7N7 acid
Authors: Skarda V. , Ivkovich D. 
Published: May 2005

AbstractThe preparation of a new type of thermally stable (up to 385°C) heterocyclic polymer, containing a five‐membered fused ring system, is described. The ultraviolet, visible, and infrared spectra indicate that this solid‐state polymerization probably proceeds via formation of an azomethine‐type intermolecular crosslink, rather than via opening of the C4N4 ring system. The reaction is facilitated by the presence of reactive protons, which act as an efficient catalyst for this nucleophilic addition to the nitrile group. It is suggested that this type of solid‐state polymerization may possibly be carried out on a single HC7N7 crystal resulting in a fully ordered macroscopic polymer single crystal.
Dehydrochlorination of polyvinylidene chloride (PVDC) in the presence of crown ether as a phase transfer agent
Authors: Yie‐Shun Chiu , Jagur‐Grodzinski Joseph , Vofsi David 
Published: May 2005

AbstractFilms of polyvinylidene chloride (PVDC) were heterogeneously dehydrochlorinated by reacting them with KF‐crown and KOH‐crown complexes dissolved in benzene. Solutions were in contact with an excess of unhydrous salts. This three‐phase reaction was very fast at 80°C and the removal of one chlorine atom per monomer unit was completed within 1 h. Further dehydrochlorination leads to triple‐bond formation and to aromatization of the system due to the intramolecular 1,6 elimination. The former reaction is dominant when KOH‐crown is used as the dehydrochlorinating agent and the latter is dominant in KF‐crown/CaO systems. The apparent energy of activation of the initial dehydrochlorination process is estimated to be 6.7 kcal./mol.
Theoretical Prediction of Energy Consumption and Particle Size Distribution in grinding and drilling of brittle materials
Authors: Weichert Reiner 
Published: May 2005

AbstractBased on physical assumptions, simple equations have been derived for the probability of breakage of particles, for the dependence of fragmentation energy on particle size and for the fragment size distributions as a function of mass‐specific energy. The particles were considered as spheres, and Hertz theory of the stress distribution at the contact between a sphere of brittle material and a flat surface was applied in combination with Weibull statistics of failure. The predicted dependence of the probability of breakage on particle size and mass‐specific energy agrees well with experimentally obtained data for single‐particle experiments, even if the particles were not spherical. The resulting fragment size distribution could be predicted by the application of fracture mechanics. The theory can also be applied to rock drilling, where the breaking material is considered as a flat surface and the drilling tool as being of spherical shape. In both comminution and drilling, the experimental results agree fairly well with the theory.
Influence of the Particle Size Distribution on the flow behaviour of fine powders
Authors: Köhler Thomas , Schubert Heinrich 
Published: May 2005

AbstractSome results are presented of investigations on the flow behaviour of very fine α‐alumina powders having different particle size distributions. Shear tests were performed in a translation shear cell. The humidity was in the range 0.3 < pD/pSD < 0.6 in order to ensure the formation of adsorbed water layers only and to exclude capillary condensation. In the region of adsorbed layer bondings, the flow behaviour of very fine powders deteriorates in comparison with regions where no adsorption layers exist. An extrapolation of the unconfined yield strength for very low consolidation stresses results in an approximately constant value for different particle size distributions. In contrast, the slope of the linear function σc = f (σ1) increases with decreasing particle size up to a certain limit. For narrow particle size distributions, there is a pronounced decrease in the bulk density with decreasing particle size. Further, the bulk density is strongly influenced by the width of the distribution.
A Re‐Examination of Piper's Shape Analysis Technique
Authors: Pickett James , Clark Nigel , Shuker Stephanie 
Published: May 2005

AbstractAn image shape analysis technique which measured the angles between adjacent vectors on the image edge was previously proposed by Piper, but the accompanying data was scant. This method is shown to have great promise when applied to several images obtained using a video camera with a computer. Better data representation is obtained using a single plot of the average measured angle at each step length versus the step length. Both scale and degree of maximum roughness are immediately evident on this plot. The measured angles may be corrected to remove image circularity effects from the angles, in which case some macroscopic shape effect is also described by the plot. Similarity with the Richardson (fractal dimension) plot is discussed.
Particle Turbulent Dispersion in 3D Magnetic Fields by using a Lagrangian approach
Authors: Berlemont Alain , Desjonqueres Philippe , Gouesbet GéRard 
Published: May 2005

AbstractA Lagrangian approach is presented for the prediction of 3D dispersion in turbulent flows. A brief description of the main characteristics of the code PALAS (Particle Lagrangian Simulation) is given and the different methods for the simulation of either a fluid particle trajectory or a discrete particle trajectory are outlined. Comparisons with experimental results for particle 3D dispersion in grid turbulence with a nonhomogeneous force field are presented and proved to be very satisfactory in most instances.
Monitoring the Coating of Powder Particles by the measurement of the low frequency impedance of the powders
Authors: Hawkins E. , Harnby Norman 
Published: May 2005

AbstractExperiments with a purpose built cylindrical capacitor are used to determine the sensitivity of low frequency impedance measurements to changes in the coatings of four different industrial powders. It is demonstrated that the technique should be suitable for off‐line quality control.
Performance of Disposable Respirators
Authors: Fardi Behzad , Liu Benjamin Y. H. 
Published: May 2005

AbstractAn experimental study of the filtration performance of several commercially available, NIOSH‐approved, disposable respirators was conducted using monodisperse DOP and NaCl particles with diameters in the 0.035 to 4 μm range.The aerosol penetration through the respirators were measured at flow rates of 16, 28 and 48 L/m using a condensation nucleus counter, an aerodynamic particle sizer, and a laser optical particle counter for purposes of comparison. The results obtained by these instruments were found to be in good agreement with each other in the overlapping region of particle size of the instruments.The peak penetration through the respirator filters was found to range from approximately 1.2% to 30% at 16 L/m, 3.5% to 37% at 28 L/m, and 6% to 45% at 48 L/m. The most penetrating particle size was found to lie in the 0.1 to 0.4 μm diameter range. Further, no significant difference in penetration for NaCl and DOP particles was found, suggesting that the particlebounce effect was not important in the present study.
The Influence of Temperature in the Range from 77 k to 338 k on the Detonation Velocity of RDX/TNT 60/40
Authors: Hollenberg K. 
Published: May 2005

AbstractThe detonation velocity of rods made of RDX/TNT 60/40 was determined with high accuracy in the temperature range from 77 K to 338 K. It was found out that the detonation velocity decreases with increasing temperature. To explain this thermodynamically unusual behaviour it is assumed that the effect of the increase of the detonation velocity with increasing temperature is superposed on the decrease caused by the simultaneous decreasing density of the explosive.
Shock Initiation of PBX‐9404 by electrically driven flyer plates
Authors: Weingart R. C. , Jackson R. K. , Honodel C. A. , Lee R. S. 
Published: May 2005

AbstractThe shock initiation threshold of PBX‐9404 has been studied over the pressure range 3.1 GPa‐28 GPa with pulse lengths ranging from 0.007 μs‐0.63 μs. The short‐duration, high pressure pulses were produced by the impact of thin plastic flyer plates accelerated by electrically exploded metal foils. We performed the experiments on explosive pellets 25.4 mm in diameter with thicknesses of 6.0 mm, 10.1 mm and 19.1 mm. No dependence of the initiation threshold on pellet thickness was observed. The data are represented reasonably well by either the critical initiation energy or by the constant P2τ initiation criteria.
A Comparative Study on some Explosive Properties of cobalt picrate and cobalt picramate
Authors: Agarwal J. P. , Agrawal (late) S. P. 
Published: May 2005

AbstractCobalt picrate and cobalt picramate were prepared, their IR spectra were recorded in KBr. Explosion delay, explosion temperature, activation energy, and explosion pressure were measured. Cobalt picrate is thermally more stable than cobalt picramate.
The Dynamic Shear Storage Modulus of Plastic‐Bonded Explosives and its relationship to sensitivity
Authors: Matuszak M. L. , Upham D. L. , Hildner R. A. , Shaw M. T. 
Published: May 2005

AbstractThe linear dynamic mechanical properties of plastic‐bonded explosives (PBXs) were measured from −40 °C to +50 °C over the frequency range of 0.1 Hz to 4 Hz with a Rheometrics dynamic mechanical spectrometer. The purpose of the measurements was to develop correlations between the viscoelastic properties of composite high explosive systems and their impact sensitivities. Data from drop‐skid tests using the 45°‐angled target, as performed by the Los Alamos Scientific Laboratory (LASL), were used in the sensitivity measurements. The skid‐test drop height was inversely proportional to the shear storage modulus of the PBXs and the glass transition temperature (measured dynamically) of the PBXs tested.
Quantum Mechanics and Molecular Dynamics Calculations provide new evidence for a free‐radical shock initiation model
Authors: Walker F. E. 
Published: May 2005

AbstractThe contrast between a hydrodynamic model for shock initiation of explosives and a newer microscopic free‐radical model is presented. The primary considerations of the free‐radical model are that shock energy is very coherent and that it is strong enough to cause mechanical fracture of covalent bonds. The shock front on a microscopic scale is very narrow (∼5 Å to 15 Å) and thermal equilibrium does not exist in the front. The free atoms and radicals formed by the shear and acceleration forces in the shock front initiate the chemical reaction that leads to hot spots and the eventual decomposition of the explosive materials. Energy‐release rates and vibrational velocities of the covalently bound atoms are factors in establishing detonation velocities. A number of explosives phenomena are discussed as the new model provides explanations for them. New information from molecular dynamics and quantum mechanical calculations on shock waves in condensed systems and recent experimental data are shown to support the free‐radical model.
Removal of 2,4,6‐trinitrotoluene (TNT) and 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX) from aqueous solutions with surfactants
Authors: Okamoto Y. , Chou E. J. , Croce M. , Freeman D. , Roth M. , Colitti O. 
Published: May 2005

Abstract2,4,6‐Trinitrotoluene (TNT) was found to react in aqueous solution with surfactants containing amino and quaternary ammonium groups at pH 10–11 at ambient temperature. The surfactants investigated included N‐tallow 1,3‐diaminopropane, trimethyl N‐tallow ammonium chloride and N,N,N′,N′,N′‐pentamethyl N‐tallow 1,3‐propane diammonium dichloride. The reaction products were insoluble in water and readily separated through filtration. The dried solids were not explosive and the solids burned without explosion. The results showed that TNT can be reduced to less than 0.1 ppm from the initial concentration of 110 ppm in 2–3 hours. The wastewater of Composition B contains TNT and 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX). Treatment of the wastewater with the ammonium cationic surfactants showed that TNT was removed quantitatively by precipitation and RDX was simultaneously hydrolyzed. The mechanism of this treatment is discussed.
Etude mécanique de chargements moulé‐collés en propergol doublebase composite par Une méthode viscoélastique non‐linéaire
Authors: Meili G. , Dubroca G. , Pasquier M. , Thépenier J. 
Published: May 2005

AbstractL'article présente une méthode d'étude mécanique de chargements moulé‐collés en propergol double‐base composite (en abrégé DBC) soumis à des cycles thermiques. La méthode proposée pour déterminer les contraintes et le coefficient de sécurité est basée sur le comportement non‐linéaire et la compressibilité du propergol. Le comportement non‐linéaire est obtenu d'après des essais de traction. Les équations d'équilibre sont résolues numériquement en découpant l'épaisseur de propergol en plusieurs couches. Les non‐linéarités affectent essentiellement le module et on utilise un critère multiaxial et l'équivalence temps‐température. On calcule à chaque pas de temps et pour chaque couche la température, le temps réduit, le facteur non‐linéaire, le coefficient de Poisson, et le dommage (selon le concept de Farris). Différents types de chargements (bloc à canal central étoilé, à mamelles, finocyl) ont été soumis à différents types de cycles thermiques. La comparison entre prédiction et expérience est convenable même pour des enchaînements complexes d'allongement et de température.
Effect of Burning Rate Modifiers on Propellant Performance. A theoretical study
Authors: Madhavan N. S. , Thanki K. P. 
Published: May 2005

AbstractThe addition of burning rate enhancers or suppressers in solid propellant composition is seen to affect the energy level considerably. In the present paper, an attempt is made to quantify such effects. Even though the study is carried out over the theoretical values of the performance parameters, the trends in the variations and the corrections occurring therefrom for the inclusion of burning rate modifiers seem to be applicable to the delivered or the actual values also more or less equally.
New Procedures for Purifying TNT
Authors: Gilbert E. E. , Siele V. I. , Chandler C. D. , Mundy R. A. , Spencer J. R. , Gibson G. R. , Bolleter W. T. 
Published: May 2005

AbstractAmmonium and magnesium sulfites were tested for purifying crude TNT in comparison with the conventional (“sellite”) process using sodium sulfite. The magnesium process easily gave an acceptable product in better yield, of higher quality, and at lower estimated cost. Magnesium values suitable for recycle were recovered from the waste water by calcination. The ammonium process gave an acceptable product only under specific reaction conditions, but the waste water can be recovered by mixing it with TNT process spent sulfuric acid, thereby eliminating a calcination step.
The Chemistry of Detonations. IX. Some observations regarding a computer based parametric study of detonation characteristics of CHNO explosives
Authors: Short J. M. , Eccleston H. F. , Baroody E. E. , Mueller K. F. , Kamlet M. J. 
Published: May 2005

AbstractSwaminathan and Rajagopalan (S and R) have recently published a parameter study describing the dependence of important detonation characteristics of CHNO explosives on their densities and enthalpies of formation which is seriously inconsistent with earlier highly reliable calculations by Mader using the same equation of state and presumably the same input information. S and R's computer‐based conclusions are also not in accord with parametric relationships established over a decade ago by Johansson and Persson and Kamlet and Jacobs. S and R's calculated detonation pressures are significantly lower at high loading densities and higher at lower loading densities than Mader's corresponding calculations. Also out of line on the high side (compared with Mader's calculations or experimentally observed values) are S and R's calculated detonation velocities. The differences between S and R's parametric relationships and those of the other workers can have important and misleading implications to the planning of future explosives chemistry research. It is suggested to those interested in such parametric studies that the simplified method for detonation property calculation be used, since the input information is explicit and easily checked and the results are at least as reliable as those from complex computer programs.
Synthesis and Properties of 1,1,1,3,5,5,5‐Heptanitropentane
Authors: Klager K. , Smith R. M. 
Published: May 2005

AbstractA nearly zero oxygen balance of organic compounds is characteristic for explosives and high performance solid rocket propellants. Because of its high oxygen content, the introduction of a trinitromethyl group into suitable organic compounds presents an attractive and simple way to produce new explosives. The reaction of 2‐nitro‐3‐acetoxy‐1‐propene with nitroform is described which yields 1,1,1,3,5,5,5‐heptanitropentane. The properties of this compound are described to assess the usefulness of this explosive in a comparison with known explosives of similar structure using theoretical calculations for the lead block, ballistic mortar and detonation properties. Although a possibility exists to introduce another nitro group in position 3 which would produce a compound with even higher oxygen balance, all attempts so far have not achieved this desirable goal.
Explosively Disseminated Colored Smokes
Authors: Webster H. A. 
Published: May 2005

AbstractThe use high decomposition temperature fluorescent dyes to produce explosively disseminated colored smoke puffs has been demonstrated. The dye material used was a commercially available pigment that was a solid solution of an organic fluorescer in a polyamide resin. Practice shells were loaded with the fluorescent dye and the payload ejected with a black powder charge. Large, highly colored smoke clouds were produced by this method. The fluorescence spectra of the dyes and calculations of increased acquisition range due to the added fluorescence are presented.
Approximate Method of Calculating Critical Shock Initiation conditions and run distance to detonation
Authors: Andersen W. H. 
Published: May 2005

AbstractAn approximate model for pressure buildup behind the front of an initiating shock wave is developed. This model leads to the widely used P2t initiation criterion, but the pressure index is not limited to a value of two. Expressions for wave run time and distance to detonation are also obtained. The use of the model is illustrated using explosives widely discussed in the literature. It is shown that critical shock initiation and run distance to detonation can be rapidly estimated to good approximation over a wide range of shock conditions from the results of one or two relatively simple experiments. The calculational method may be useful for various applications.
Auto‐inflammation de la nitrocellulose
Authors: Isler J. 
Published: May 2005

AbstractLes résultats présentés dans cet article composent le premier volet d'une étude menée au GERPy sur l'auto‐inflammation des munitions chargées en poudre à base de nitrocellulose. Une corrélation entre la cinétique de décomposition et l'auto‐inflammation d'échantillons cylindriques homogènes a été établie après modélisation du phénomène. Le modèle décrit permet de déterminer les profils de température ainsi que la température critique.
The Double Pipe Test for Commercial Explosives II. Numerical modelling and interpretation
Authors: Lownds C. M. , Du Plessis M. P. 
Published: May 2005

AbstractAn approximate numerical model of the Double Pipe Test has been devised to examine the effects of properties of the top pipe, witness pipe and the explosive on the depth of dent generated in the witness pipe. The model is based on a static calibration of the strength of the witness pipe, with strain‐rate correction for high rates of loading. The inertia of all material accelerated by the explosive product gases is also considered. A comparison of predicted and measured dent depths for various peak explosive pressures shows that the model adequately describes dynamic behaviour during the test. Measured dent depths are expected to correlate with the ability of an explosive to generate a shock wave in rock.