bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of glycidol and its derivatives: A new rearrangement polymerization
Authors: Vandenberg E. J. 
Published: May 2005

AbstractAnionic (KOH) polymerization of glycidol, or its trimethylsilyl ether (TMSGE) followed by hydrolysis, gives a low molecular weight, largely amorphous polymer that is not the reported 1,3‐polyglycidol but, based on 13C‐NMR, largely a 1,4‐poly(3‐hydroxyoxetane) with much branching. This result is achieved by a simple rearrangement of the usual, propagating secondary oxyanion to a primary one. Substantial amounts of four dimers (5–10%), four trimers, and some tetramers were also found. One dimer was isolated and shown to be glycidyl glycerin, the usual thermal dimer from glycidol. Possible structures of the other dimers are proposed. The polymerization appears to begin with the rapid formation of the glycidoxy anion , formed by base abstraction of a proton from glycidol and by nucleophilic displacement of the SiMe3 group from TMSGE. Other bases such as KOtert‐Bu give similar 1,4 polymer for glycidol but, with TMSGE, there is considerable 1,3 polymerization. Detailed mechanisms are proposed. The polymer perpared from R‐TMSGE with KOH was highly crystalline, high melting (166°C), H2O soluble, isotactic poly(3‐hydroxyoxetane). The cationic polymerization of tert‐butyl glycidyl ether (TBGE) and TMSGE gave low molecular weight 1,3 polyethers. The TBGE polymer was all head‐to‐tail whereas the polyglycidol from TMSGE contained extensive head‐to‐head chain units with considerable branching. Mechanisms for these interesting differences are proposed.
A study of molecular weight of methyl methacrylate–styrene copolymer
Authors: Bataille Pierre F. , Granger Francois 
Published: May 2005

AbstractAn alternating copolymer of methyl methacrylate and styrene was obtained by the reaction of these two monomers in the aqueous phase and in presence of zinc chloride acting as complexing agent. It was found that the optimum conditions were obtained when the monomer concentrations are equal. The molecular weight and the molecular weight distribution were obtained by gel permeation chromatography (GPC). The polymers obtained have a very narrow molecular weight distribution. A model which takes into account the various parameters is proposed.
Analysis of some phenolic copolymer mixtures by electrometric titration techniques
Authors: Chatterjee S. K. , Katyal Anita 
Published: May 2005

AbstractSome two‐, three‐ and four‐component phenolic copolymers have been characterized, and mixed in definite stoichiometric proportions. The total amount of acidic and basic functional groups in a given weight of the copolymer mixture have been calculated from the characteristic parameters of the polymer components. Analysis of these copolymer mixtures by electrometric titration techniques revealed an excellent correlation between the calculated and observed values of functional groups.
Thermal polymerization of N‐tert‐butylacrylamide in 1,4‐dioxane
Authors: Aşikoğlu Bi̇lge , Kiliç Soner , Baysal Bahatti̇n M. 
Published: May 2005

AbstractThe kinetics of the thermal polymerization of N‐tert‐butylacrylamide were investigated in 1,4‐dioxane as solvent, in the 65–80°C temperature range. It was found that the overall rate of polymerization which was determined by a gravimetric method is proportional to the 1.9 power of monomer concentration at 70°C. The rate of initiation was determined by ESR spectroscopy using DPPH as an inhibitor, and it was found that the order of initiation rate is 1.8 with respect to monomer concentration at 70°C. The overall activation energy for the thermal polymerization of N‐tert‐butylacrylamide was found to be 64 ± 9 kJ mol−1 in the 65–80°C temperature range. The activation energy for the rate of initiation was also determined and it was found to be 90 ± 23 kJ mol‐1.
The effect of molecular weight on the behavior of hydrophobic polyacids
Authors: Strauss U. P. , Andrechak J. A. 
Published: May 2005

AbstractThe effect of the degree of polymerization on the potentiometric titration behavior of alternating copolymers of maleic anhydride and alkyl vinyl ethers was investigated. Apparent abnormalities in the titration curves of the lower oligomers were attributable to endgroups. After accounting for these effects, the potential was found to decrease with diminishing molecular weight. However, the decreases were much more pronounced with the butyl, pentyl, and decyl copolymers which have compact conformations at low degrees of deprotonation, than with the propyl copolymer which shows random coil behavior over its whole ionization range. The standard free energy of complete deprotonation, ΔG°, generally increased with the degree of polymerization, but this increase was relatively small compared to the difference between ΔG° of the monomer and ΔG° of the lowest oligomer investigated.
Direct mass spectrometry of polymers. XII. Thermal fragmentation processes in poly‐α‐aminoacids
Authors: Ballistreri Alberto , Giuffrida Mario , Maravigna Pietro , Montaudo Giorgio 
Published: May 2005

AbstractThe thermal fragmentation processes in poly‐α‐aminoacids have been investigated by direct pyrolysis–Mass Spectrometry. The mass spectral data show that the pyrolytic breakdown of polyglycine, polysarcosine, and polyproline leads to the formation of cyclic oligomers. Polyalanine, polyphenylalanine, and polytyrosine decompose yielding compounds with olefin and nitrile end‐groups. Finally, in the case of poly‐α‐methylglutamate, the primary thermal process is the loss of methanol with consequent formation, along the polymer chain, of pyroglutamic units, which yield cyclic dimer as main pyrolysis product.
Particle Growth by Coalescence and Agglomeration
Authors: Koch Wolfgang , Friedlander Sheldon K. 
Published: May 2005

AbstractA dispersed system is considered which will form its condensed phase at high temperatures and is characterized by a high density of very small supercritical nuclei. It is assumed that particle growth is determined by coagulation and (viscous flow) coalescence. The morphology of the final particles depends on the temperature history of the formation process. Compact spherical particles and agglomerates may be formed. Agglomerates result when the process temperature decreases to an extent that coalescence is quenched in the course of the growth process. The average size of the primary particles in the agglomerates is calculated by using the analysis and the approximations described in a previous paper. The growth kinetics of the primary particles are presented in a dimensionless form. The results show that the dimensionless size of the primary particles depends only on the ratio of two characteristic lengths of the system. For small values of this ratio, the size of the primary particles composing the agglomerates, although much greater than the initially formed nuclei, is independent of the volume fraction of the condensed aerosol. For large values of this parameter, the theory merges into the classical theory of perfectly coalescing spheres.
Development of an Automatic System for Measuring Particle Charge and Size distributions in a clean room
Authors: Adachi Motoaki , Liu Benjamin Y. H. , Pui David Y. H. 
Published: May 2005

AbstractAn automatic measuring system was developed to perform simultaneous measurements of particle size and charge distributions in a clean room and other aerosol sources. The system consists of an electrostatic condenser (EC) and an optical particle counter (OPC), which are controlled by a personal computer (PC). The PC automatically varies the voltage on the EC and converts the corresponding OPC counts to charge distributions. The reliabilities of the data inversion method and the automatic measuring system were confirmed by theoretical and experimental examinations, respectively. In the theoretical examination, inverted charge distributions were tested and compared with various assumed input distributions. In the experiment where monodisperse aerosols neutralized by a 85Kr neutralizer were used, the measurement results agreed well with the theoretical Boltzmann charge distribution. The application of this technique is demonstrated by the measurement of charge and size distributions of aerosols in a clean room.
Top‐Hat Beam Technique: Improvements and application to bubble measurements
Authors: Corbin Frédéric , Gréhan Gérard , Gouesbet Gérard 
Published: May 2005

AbstractA new‐generation velocimeter/sizemeter is described. Size measurement is based on the top‐hat beam technique. Velocity measurement is carried out by using laser Doppler velocimetry. Advantages and limitations of the top‐hat beam technique are discussed and compared with other techniques (pedestal, visibility, phase Doppler). Bubble diagnosis in a turbulent pipe flow is reported.
Design Data for Cyclones
Authors: König Christine , Büttner Helmut , Ebert Fritz 
Published: May 2005

AbstractFor many years efforts have been made to describe the complex process of particle separation in cyclones, and a multitude of separation models have been set up. A comparison of such separation models fails because insufficient usable test results are available and systematic and precise investigations are missing.It is important for the design of cyclones to rate their separation properties by means of the fractional collection efficiency. On account of the known measuring problems, the data supply of reliable fractional efficiency curves of cyclones is still too small. Fractional efficiency as a function of the entrance velocity was measured with a high‐speed optical measuring technique. Measurements of low dust concentrations are presented. Geometrically similar cyclones of four different sizes were investigated. The fractional efficiency curves are plotted versus dimensionless parameters and the validity of the design criteria gained in this way is shown. The influence of particle shape on the fractional efficiency curves is discussed.
Contribution à l'Etude de la Thermolyse de la Nitroglycérine
Authors: Caire‐Maurisier M. , Tranchant J. 
Published: May 2005

AbstractPar l'utilisation de méthodes analytiques modernes, telles que la résonance paramagnétique électronique, la spectrophotométrie infrarouge avec étude des déplacements de masse, la spectrométrie de masse et la fragmentométrie, combinées avec des analyses de gaz et des couplages chromatographie‐spectrométrie de masse, on a pu mettre en évidence le caractère radicalaire de la décomposition thermolytique de la nitroglycérine, puis proposer une série de réactions secondaires aboutissant aux produits de réaction observés.
A Unique Failure Criterion for Characterizing the Fracture of Propellants
Authors: Gledhill R. A. , Kinloch A. J. 
Published: May 2005

AbstractThe problem of crack growth in a nitrocellulose/nitroglycerin propellant has been studied employing a continuum fracture mechanics approach. Values of the stress‐intensity factor, Kc, at the onset of crack propagation have been ascertained and found to be dependent upon both the thickness of the specimen and the test temperature. By proposing that the value of Kc arises from the sum of a plane‐strain and a plane‐stress component a unique failure criterion, which is constant over a wide temperature range, has been identified. Namely, that crack propagation in the propellant occurs when the plane‐stress plastic‐zone at the crack tip attains a critical size.
Separation and quantitation of nitrocellulose, nitroglycerin, diethylphthalate, and centralite in double‐base powder
Authors: Sjöbom R. A. , Oresten H. G. 
Published: May 2005

AbstractA method is described which makes possible a direct determination of nitrocellulose in double‐base powder and powder paste after separation from low‐molecular components by gel permeation chromatography and subsequent integration of the nitrocellulose peak. It is also possible to determine nitroglycerin and stabilizers in the same sample by collecting the components in the low‐molecular peak and subsequent injection into a reversed‐phase chromatography system. The procedure is exemplified on a powder paste containing nitrocellulose, nitroglycerin, centralite I, and diethylphthalate. The whole quantitation procedure will take less than an hour.
Free Radicales of TATB
Authors: Britt A. D. , Moniz W. B. , Chingas G. C. , Moore D. W. , Heller C. A. , Ko C. L. 
Published: May 2005

AbstractTATB (1,3,5‐triamino‐2,4,6‐trinitrobenzene) forms an unusually stable free radical upon irradiation with ultraviolet light. Extraction with dimethylsulfoxide yields a liquid solution ESR spectrum which is, apparently, due to a TATB‐H adduct. The g‐values, spectral widths, and hyperfine assignments for the solution radical are given.
Some Observations on Sublimation and Decomposition of Ammonium Perchlorate
Authors: Pai Verneker V. R. , Kishore K. , Chaturvedi B. K. , Ramanath M. 
Published: May 2005

AbstractAmmoniumperchlorate (AP) was aged at 100 °C and 150 °C. Depending on the aging time, AP shows different decomposition characteristics. By a special experimental arrangement sublimation and thermal decomposition could be separated.
Effect of Lead and Copper Methylene Disalicylates on the combustion rates of double‐base rocket propellants
Authors: Singh H. , Rao K. 
Published: May 2005

AbstractThe effect of lead and copper methylene disalicylates and their mixtures was studied on the burning rates (35 kg/cm2‐140 kg/cm2), heat of explosion, stability and thermal decomposition of double‐base propelants. The results indicate that these salts are very effective catalyst and their mixtures produce super‐rate burning (140% increase) with a uniform pressure index value in the entire pressure range. These additives lower “n” value to about 0.2–0.3 in some of the pressure regions. Results of DTA study suggest that these additives decompose in an exothermic mode in the temperature range close to the surface temperature of double base propellants.
Quelques propriétés physico‐chimiques des Solutions aqueuses de perchlorate d'ammonium
Authors: Hiquily N. , Laguerie C. 
Published: May 2005

AbstractLa solubilité du perchlorate d'ammonium dans l'eau, la masse volumique, la viscosité, I'indice de réraction et la conductivité électrique des solutions aqueuses ont été mesurés et comparés à d'autres valeurs de la bibliographie.
The Detonation Properties of Explosive‐Water Mixtures
Authors: Zygmunt B. 
Published: May 2005

AbstractMixtures of crystalline explosive and water have as a rule detonation properties different from the dry material. It has been shown that the character of those changes is closely related to the structure of the particles (crystals, granules) of the explosives. The critical diameters and detonation velocities have been measured for a range of explosive‐water mixtures, and the results are interpreted in terms of the hotspot theory.
Vereinfachte gasvolumetrische Gehaltsbestimmung von Diazodinitrophenol
Authors: Runge‐Eschen F. , Helbig G. 
Published: May 2005

AbstractDiazodinitrophenol wird durch Reduktion der Diazonium‐Gruppe zu molekularem Stickstoff in einer Sandmeyer‐Reaktion mit CuCl oder durch Umsetzung mit TiCl3 quantitativ bestimmt. Da diese Reaktionen selektiv verlaufen, stören nitrogruppenhaltige Beimengungen nicht. Zur vereinfachten routinemäßigen Durchführung wird ein modifizierter Schulze‐Tiemann‐Apparat verwendet.
Thermal Decomposition of Tetraethylammonium Perchlorate
Authors: Udupa M. R. 
Published: May 2005

AbstractThermal decomposition of tetraethylammonium perchlorate has been studied by thermogravimetry, differential thermal analysis and mass spectrometry. The title compound undergoes crystallographic transformation at 98°C and explodes at 298°C. The heat of phase transformation is calculated to be 2.5 kcal/mol. The mass spectral data suggest that the salt undergoes thermal decomposition into neutral particles which are then vapourized and ionized as well as oxidized.
Thermal Study on Picryl Azide (2‐azido‐1,3,5‐trinitrobenzene) decomposition using simultaneous thermogravimetry and differential scanning calorimetry
Authors: Reddy G. Om , Murali B. K. Mohan , Chatterjee A. K. 
Published: May 2005

AbstractThermal decomposition of picryl azide has been studied under non‐isothermal and isothermal conditions using a simultaneous TG‐DSC technique. Picryl azide melts and then decomposes to give 4,6‐dinitrobenzofurazan oxide which melts again and decomposes to gaseous products. Enthalpies (ΔH) of fusion and decomposition have been calculated. The order of reaction (n) is calculated and found to be one. Arrhenius parameters like specific rate constant (k), activation energy (Eact) and frequency factor (Z) have been calculated under both conditions using different methods. The values calculated from non‐isothermal and isothermal techniques agree fairly well with each other. The observed lower activation energy when compared with phenylazide and 2‐nitrophenyl azide is probably due to an enhanced ortho effect.
Contribution à l'étude de propriétés des molécules d'explosif dans l'état active. II. Volumes molaires des derivés nitrés aromatiques
Authors: Bernard M. L. 
Published: May 2005

AbstractLes incréments de volumes moléculaires affecté à chaque atome ou groupement d'atomes ont été déterminés sur dix explosifs aromatiques nitrés, tant à l'état cristallin qu'à l'état activé, au sens de la théorie cinétique de la détonation. Comme dans le cas des esters nitriques, on constate que seuls les groupements explosophores sont comprimés, ainsi que le groupe phénol. Les autres atomes ou groupements ont des volumes voisins de ceux déterminés dans les cristaux d'après les règles d'additivité établies récemment dans les solides cristallins.
Some Experiments on Model Composite Solid Propellants
Authors: Ramaprasad P. R. , Raghunandan B. N. , Mukunda H. S. 
Published: May 2005

AbstractExperiments on two‐dimensional model propellants using cylindrical oxidizer (ammonium perchlorate) pellets in a fuel matrix (CTPB) are described. Measurements show that burning rate of AP in the fuel environment is lower than of pure AP. The oxidizer‐to‐fuel ratio seems to be fuel‐rich when the oxidizer particles are imbedded in contact with the fuel and it becomes oxidizer‐rich for a non‐zero separation between oxidizer particle and the fuel.
Décomposition thermique en phase gazeuse du nitrate d'isopropyle
Authors: Jullien J. , Pechine J.‐M. , Perez F. , Sadek M. A. 
Published: May 2005

AbstractLa décomposition thermique en phase gazeuse homogène du nitrate d'isopropyle a été étudiée dans un tube à choc unique. On a utilisé une méthode comparative avec le peroxyde de di‐t‐butyle comme référence interne. Sur l'intervalle de température de 533 K à 635 K, l'expression de la vitesse pour cette décomposition du nitrate d'isopropyle obéit à la relation:
Identification of Combustion Products from Colored Smokes containing organic dyes
Authors: Chin A. , Borer L. 
Published: May 2005

AbstractDevices producing different colored smokes have been widely used by military and civilians for signaling, screening, and display. Attention has not yet been placed on the analysis of the combustion products from these devices which may be hazardous. Combustion products from these colored smokes containing organic dyes produced at the normal function temperature (approximately 400°C–600°C) of the compositions have been studied in our laboratory. The five dyes contained in the smoke compositions studied are: benzanthrone, dibenzo(a,h)pyrene‐7,14‐dione, 1,4‐di‐p‐toluidino‐anthraquinone, 1‐methylamino‐anthraquinone, and α‐xylene‐azo‐β‐naphthol. A modified EPA‐Method 5 sampling train containing Amberlite XAD‐2 as the absorbant was used to sample the organic vapors and particulates in the effluent. ánalytical methods used to separate, purify, and identify the products include TLC, HPLC, GC, GC‐MS, and NMR.Minimum destruction of the organic dyes is desired for a good smoke. Our preliminary investigations indicate that 90%–95% of the organic dye sublimes while the other 5%–10% is lost to combustion. The combustion products observed, to date, have been identified as polynuclear aromatic hydrocarbons (PAH's) and polynuclear organic materials (POM's) which are the result of thermal decomposition and thermal rearrangement of the parent dyes. At the temperature of functioning, no ring opening of the dyes has been observed.
The Potentiometric Titration of Aluminum in Explosives
Authors: Selig W. 
Published: May 2005

AbstractAluminum in explosives is determined after sample dissolution with concentrated nitric acid. The pH of suitable aliquots, containing from 5 mg to 10 mg of aluminum, is adjusted to 3.4 to 3.8 with solid sodium acetate. Solutions are then titrated potentiometrically with 0.5 M sodium fluoride. The emf's are monitored with a fluoride ion‐selective electrode and a single‐junction reference electrode.
Oil/High Explosive Compatibility Study. Selection of safing fluids for damaged explosives assemblies
Authors: Harris B. W. 
Published: May 2005

AbstractA series of explosive compositions was treated with commercially available oils. Samples were analyzed by differential thermal analysis, accelerating rate calorimetry, and drop‐weight impact test. Results were compared with those of the untreated compositions. Some systems showed definite incompatibilities. These data are beneficial to individuals who must select safing fluids for desensitizing explosives contained in assemblies that are damaged as a result of an accident. This is especially true where broken pieces of high explosives might rub together or against metal surfaces, thus causing increased hazards during handling operations.
Some Observations on the Thermal Stability of double‐base propellants
Authors: Kishore K. , Pai Verneker V. R. , Subhas C. B. V. 
Published: May 2005

AbstractHeats of decomposition and explosion of double base propellants were measured as a function of aging time. They show opposite trends with aging time: heat of decomposition shows a gradual increase and heat of explosion a systematic decrease. This happens because nitroglycerin oozes out of the system during aging. The loosening of the bond between the liner and the propellant during aging was shown to be due to the contraction of the propellant which occurs on account of nitroglycerin migration from the propellant system.
Use of NMR Spectometry for studying the acetolysis of hexamethylenetetramine. I. The reaction of TAT formation from DAPT
Authors: Ju Chen , Shao‐Fang Wang 
Published: May 2005

AbstractThe reaction of forming TAT from DAPT was followed by 1H NMR spectroscopy. This investigation shows that water or ammonium acetate quickens the reaction and they do take part in the reaction. Reaction intermediates were detected and according to the information obtained by NMR, their structures were postulated to be X or X1 in the absence or presence of water respectively.magnified imageThe kinetic study further indicated that acetylation of X1 to TAT is first order in X1 and in acetic anhydride. In other words, it is a bimolecular reaction. The rate constant k was found to be 1.46 × 10−4 mol−1 · s−1.
Smoke Generators. III. The ignition of pyrotechnic white smoke compositions containing hexachloroethane, silumin and metal oxides using a heated metal surface
Authors: Hartley F. R. , Murray S. G. , Williams M. R. 
Published: May 2005

AbstractThe addition of metal oxides to silumin‐hexachloroethane pyrotechnic smoke mixtures makes ignition on a hot plate more difficult in the order aluminium oxide < zinc oxide < magnesium oxide. Evidence is presented that suggests that aluminium oxide inhibits ignition by acting as an inert diluent separating the active reactants whereas the effect of magnesium oxide is believed to be chemical in nature. The addition of small amounts of ferric oxide or potassium iodide has little effect on the onset of smoke formation in a silumin‐hexachloroethane‐zinc oxide composition but promotes the transition from smoke to flame reaction. In contrast small amounts of either iodine or trityl chloride inhibit the onset of the smoke reaction. A mechanism is proposed for the ignition of silumin‐hexachloroethane compositions that accounts for these observations.