bluuebunny/crossref_metadata_2025 huggingface dataset:
Permeable boundary condition for numerical simulation in resin transfer molding
Authors: Wu Ching‐Jenn , Hourng Lih‐Wu
Published: May 2005

In the present study of resin transfer molding, an effective gap located between the side wall and the fiber mats is proposed. The concept of the effective gap leads to a permeable boundary condition on the interface between the fiber mats and the side wall. The porosity is no longer assumed to be a constant in the whole domain. Results show that the effective gap concept can explain the phenomena of edge effects reasonably. In our model, the filling process is simulated by the body‐fitted finite element method and the limitation of the time increment for the quasi‐steady state process is discussed in detail.
Aromatic polyetherimides as promising fusible film binders
Authors: Svetlichnyi V. M. , Zhukova T. I. , Kudriavtsev V. V. , Yudin V. E. , Gubanova G. N. , Leksovskii A. M.
Published: May 2005

Polyetherimides (PEI) based on dianhydrides of 3,3′, 4,4′‐dipheniloxytetracarboxylic acid and 1,3‐bis‐(3,4‐di‐carboxyphenoxy)benzene that contain fragments of such thermoplastic polymers as poly(ether sulfone) or poly(phenylene oxide) have been synthesized. Thermoplastic properties of synthesized PEI were characterized by flow temperature Tf and melt viscosity ηm. The properties obtained are outstanding for the production of PEI as fusible film binders, and composites can be produced without toxic solvents. Carbon fiber reinforced plastics (CFRP) based on PEI films were analyzed using an Acoustic Emission (AE) technique.
Mechanisms of mixing in single and co‐rotating twin screw extruders
Authors: Lawal Adeniyi , Kalyon Dilhan M.
Published: May 2005

Previous experimental studies have revealed that the mixing efficiencies of widely used continuous processors such as the single and twin screw extruders depend on the types of screw elements, which are utilized. It is generally recognized that the basic single screw extruder and the fully‐fighted sections of the fully‐intermeshing co‐rotating twin screw extruders are not efficient mixers, in contrast to the specialized mixing elements such as the kneading discs used in co‐rotating twin screw extruders. However, no simulation techniques were available to characterize quantitatively and rigorously the mixing efficiencies of continuous processors. In this study, we have solved the three‐dimensional equations of conservation of mass and momentum, and utilized various tools of dynamics to analyze the mixing occurring in single and co‐rotating twin screw extruders. It is shown that simulation methods can indeed capture the relative differences in the mixing mechanisms of continuous processors like the single and twin screw extruders. The ability to distinguish quantitatively between the distributive mixing capabilities of various continuous processors should facilitate numerical testing of new continuous mixer designs, optimization of operating conditions and geometries of existing mixers and the material‐specific design of new mixers.
A non‐Markovian model of desorption
Authors: Stastna J. , De Kee D. , Harrison B.
Published: May 2005

The desorption kinetics of small hydrocarbon molecules in a low‐density polyethylene (LDPE) film has been simulated via the continuous time random walk approach. A scaling relation between the amount of penetrant remaining in the film during the final stage of the process and the time has been obtained. A constant scaling exponent was obtained for various hydrocarbon penetrants in LDPE. The mutual relation between phenomenological and statistical models has been exploited.
Viscoelastic properties of acrylonitrile‐butadiene‐styrene (ABS) polymers in the molten state
Authors: Bertin Marie‐Pierre , Marin Gérard , Montfort Jean‐Pierre
Published: May 2005

The viscoelastic behavior of acrylonitrile‐butadiene‐styrene (ABS) terpolymers is studied in the molten state. First, the behavior of the styrene‐acrylonitrile (SAN) matrix is determined. Then, the effect of the degree of grafting on ABS rheological properties is emphasized. A critical degree of grafting (DGc), corresponding to a minimum of the viscoelastic functions in the low frequency region, is determined. It defines a critical thickness of the grafted layer, and is related to the conformation of the grafted chains at the surface of the rubber particle. The DGc affects the morphology of the ABS and also affects the appearance of a secondary plateau at low frequencies. The effects of the rubber particles, of the grafted chains, and of the morphology on the appearance of the secondary plateau at low frequencies are clearly dissociated.
Graft polymerization of monomers onto cellulose and lignocelluloses by chemically induced initiator
Authors: Mansour O. Y. , Nagaty A. , Beshay A. D. , Nosseir M. H.
Published: May 2005

The presence of a low percentage of lignin retards and inhibits the graft polymerization reaction of some vinyl monomers on lignocellulosic substrates. The retardation or inhibition effects of lignin in situ are discussed.
Piezoelectric polymer films. II. Piezoelectric and pyroelectric evaluation
Authors: Liepins R. , Timmons M. L. , Morosoff N.
Published: May 2005

The concept of piezoelectric and pyroelectric effects in amorphous polymers is presented, with experimental results, details on sample preparation, and activity evaluation. Most evaluations were performed on 25–30 mol% tributyltin methacrylate/methyl methacrylate copolymers, which possessed good piezoelectric activity, antifouling properties, and paint‐formulation characteristics. Solvent‐induced orientation effects that lead to piezoelectric activity in amorphous, unpoled, polymers are also described.
Phenylated polyimides via bifunctional monomers
Authors: Feld William A. , Serico Lucia , Genez Beverly G. , Friar Linda L.
Published: May 2005

The synthesis of two phenylated bifunctional monomers, dimethyl 4‐(4‐(p‐aminophenoxy)phenyl)‐3,5,6‐triphenylphthalate and dimethyl 4‐(4‐(4‐(p‐aminophenoxy)phenoxy)phenyl)‐3,5,6‐triphenylphthlate, was accomplished. Polymerization in solution or by a bulk polymerization procedure yielded a series of low molecular weight phenylated polyimides. The polymers were soluble in chlorinated hydrocarbons and exhibited thermal stabilities comparable to other polyimide systems.
Esters of alternating copolymers of maleic or 2,3‐dimethylmaleic anhydride with alkyl vinyl ethers
Authors: Xi Fu , Bassett Walter , Vogl Otto
Published: May 2005

Maleic anhydride or 2,3‐dimethylmaleic anhydride was copolymerized with a number of alkyl vinyl ethers, with AIBN as the initiator. The comonomers were always alternating and were obtained in yields ranging from 15 to 99%. The acid anhydride group in both series of copolymers was converted to the corresponding methyl esters in a two‐step reaction. The structure of these polymers was established by elemental analysis and by infrared, 1H‐and 13C‐NMR spectroscopy. Addtional characterization of these copolymers were carried out by viscosity measurements, differential scanning calorimetry for the determination of glass transition temperatures, and thermal degradation for the determination of the thermal stability of the copolymers.
Chemical modification of poly(vinyl chloride): A conclusive study of the influence of tacticity
Authors: Millán J. , Martinez G. , Mijangos C.
Published: May 2005

Three samples, A, B and C, of poly(vinyl chloride) (PVC) were prepared at 90, 60, and 0°C, respectively, to give them different isotactic content measured by 13C‐NMR spectroscopy. A kinetic study of the nucleophilic substitution with sodium thiophenate, carried out for the three samples, showed that even at temperatures as high as 60°C a fraction of the units remain unreactive and that the extent of this fraction depends on the syndiotactic content of the polymer. This was also supported by a comparison of the behavior of samples B and C in substitution experiments at 5 and 60°C. In contrast the substitution experiments at −30°C demonstrated that, as suggested, a small fraction of extremely reactive units exists in PVC, the content of which is higher as the isotactic content of the polymer increases. In this connection, and even though a slight contribution of some defect structures cannot be ruled out, a 13C‐NMR analysis of sample B after modification at 40°C to various degrees demonstrates that the reactivity of the isotactic triads is high in relation to the heterotactic. On the basis of the results obtained and the possible conformations in PVC the substitution mechanism is related to the occurrence of isotactic TT conformations. The results, as discussed in terms of the various ways in which isotactic TT conformations appear open new prospects in the field of PVC chemical modification and stabilization mechanisms.
Oligomerization of vinyl monomers 20. Carbon‐13 NMR of oligomers of 2‐vinylpyridine. Studies of labelled end groups
Authors: Huang S. Strong , Hogen‐Esch Thieo E.
Published: May 2005

Oligomers of 2‐vinylpyridine initiated with Li, Na, K, and Rb salts of 13C‐labeled or‐unlabeled 2‐ethylpyridine and terminated with 13C‐labeled or ‐unlabeled methyl iodide were separated by liquid chromatography and analyzed by 13C‐NMR of the initial or terminal CH3 group. The stereochemistry of the three dyads which flank the initial or terminal methyl group could be determined and this allowed us to evaluate the stereochemistry of both methylation and vinyl addition. The methylation of the Li and Na salts of the oligomer anions is highly (> 95%) stereoselective and independent of chain length, whereas the stereoselectivity of the K and Rb salts is substantially less. These data indicate that the Li and Na oligomer and polymer anions exist in a chelated form in which the metal ion is complexed with the penultimate 2‐pyridine group, the other counterions being chelated to a lesser extent. The stereochemistry of monomer addition was found to be less stereoselective than that of methylation for the Li and Na salts. In addition, the apparent meso‐stereoselectivity of monomer addition of the Na, K, and Rb systems was greater than that of the Li ion. For the latter system, in particular, the mechanism appeared to be Markoff‐like and consistent with different reactivities of anions flanked by a distinct dyad or triad stereochemistry. These data appear to be consistent with the intramolecular coordination that tends to hold the third asymmetric center close to the propagating carbanion.
Polyaromatic ether–ketones and ether–keto–sulfones having various hydrophilic groups
Authors: Ogawa Takeshi , Marvel C. S.
Published: May 2005

Polyaromatic ether–ketones and polyaromatic ether–keto–sulfones were sulfonated by suspending the polymer powders in dichloroethane containing liquid sulfur tiroxide and trialkyl phosphate at room temperature. It was found that more than one sulfonic group can be introduced per each repeating unit of the polymers without degradation. The sulfonated polymers were soluble in various organic solvents, and solubility and mechanical properties depended on the initial molecular weight of polymers as well as the degrees of sulfonation. Strong films can be cast from their dimethylformamide solutions.
Peculiar temperature dependence on the binding of methyl orange and its homologs by 2‐hydroxyethyl methacrylate‐N‐vinyl‐2‐pyrrolidone copolymers
Authors: Kozuka Hiroshi , Takagishi Toru , Hamano Hiromitsu , Kuroki Nobuhiko
Published: May 2005

2‐Hydroxyethyl methacrylate (HEMA)‐N‐vinyl‐2‐pyrrolidone (VPy) copolymers of various compositions have been prepared. The copolymers obtained were examined for their ability to bind a homologous series of methyl orange derivatives, methyl orange, ethyl orange, propyl orange, and butyl orange, at 5, 15, 25, and 35°C, respectively, in an aqueous solution. The first binding constants and the thermodynamic parameters that accompanied the binding were evaluated. The binding ability of the copolymer for the small cosolute was enhanced with an increase of the HEMA content in the copolymer. Moreover, a bell‐shaped curve appeared in the binding of butyl orange by the copolymers having higher HEMA residues when the first binding constant was plotted as a function of temperature, whereas no such phenomenon was detected for the copolymers with less HEMA content or for the less hydrophobic dye, methyl orange, ethyl orange, or propyl orange. This peculiar temperature dependence of the first binding constant shows that the enthalpy of the binding varies from a positive (unfavorable) value below ca. 15°C to a negative (favorable) one above this temperature. This behavior can be accounted for in terms of more hydrophobic effects involved in the binding process.
Modern Methods of On‐Line Size Analysis for Particulate Process Streams
Authors: Hobbel Erik F. , Davies Reg , Rennie Foster W. , Allen Terence , Butler Larry E. , Waters Edward R. , Smith James T. , Sylvester Robert W.
Published: May 2005

Two techniques for on‐line particle size measurement are evaluated on the reproducibility of their volume distribution determinations. A forward scattering laser light devise is interfaced with a dilutor to examine the potential of this technique for high concentration streams. The forward scattering instruments are capable of outputting extremely reproducible distributions and here we show that when the dilutor is well designed, the on‐line instrument can have similar performance. We compare this with a scanning back scatter instrument which is directly inserted in highly concentrated slurries. We present the methods used to improve the robustness of the conversion of the output of the back scatter instrument to volume distributions. The output of the back scatter instrument is inherently less stable but with the proper methods one can obtain reproducibilities of the order of 2 to 6 percent.
New Developments in Aerosol Characterization from the Physical Point of View
Authors: Schmidt‐Ott Andreas
Published: May 2005

There are a limited number of phenomena occuring with aerosol particles that depend only on physical quantities. Examples of new developments in aerosol particle characterization in situ that make use of such phenomena are briefly reviewed. They concern electrophoretic size classification, inertial size analysis and shape characterization of agglomerates. In addition to deriving basic descriptors, measurements of composite quantities can be performed and developed into sensors. Examples of sensors responding to relevant complex aerosol quantities are explained.
Characterizing the Structure of Fumed Pigments using the concepts of fractal geometry
Authors: Kaye Brian H.
Published: May 2005

Many commercially important pigments such as titanium dioxide and carbonblack are produced as fumes from a combustion process. The fuming process generates open structured agglomerates conforming to a morphology predicated by physical considerations. For this reason widely different chemical pigments often manifest common physical structure. This structure can be characterized using the concepts of fractal geometry. In this communication the potential usefulness and physical significance of descriptive parameters of the agglomerate structure of fumed pigments based on the concepts of fractal geometry are explored. Similar structures present in high energy ceramic powders are discussed and the potential importance of fractal dimension parameters for the prediction of the physical behaviour of powders is outlined.
On the Droplet Deposition and Mist Supercooling in a turbulent channel flow
Authors: Yang Z. H. , Lee S. L.
Published: May 2005

A combined experimental and theoretical study of the droplet deposition and mist supercooling in a turbulent channel flow has been performed. The measurement of droplet deposition on the unheated and heated channel wall was carried out using a particle‐sizing two‐dimensional reference‐mode laser‐Doppler anemomentry technique in a 41 mm × 41 mm vertical square channel at Re = 1.0 × 104 − 6.05 × 104. The dimensionless deposition coefficient kd/u

Z. H. Yang Prof. S. L. Lee Department of Mechanical Engineering, State University of New York at Stony Brook, Stony Brook, NY 11794 (USA)

is analyzed theoretically based on a new unified theoretical approach for the entire transverse flow region from the turbulent core to the quasi‐laminar region next to the boundary wall. The proposed analytical model shows satisfactory agreement with the results of present experimental measurement. In the mist supercooling, the heated surface is cooled by the evaporation on the outside surface of an extra thin continuous liquid film which is maintained by the continuous deposition of extremely small droplets of an optimal size determined by a selection process on the droplets transverse migration due to the dynamic interaction between the phases in a parallel turbulent mist flow. The heat transfer enhancement coefficient depends on droplet deposition rate, droplet size, concentration and the Reynolds number.
A Study of Particle Factors Affecting Dust Explosions
Authors: van der Wel Peter , Lemkowitz Saul , Scarlett Brian , van Wingerden Kees
Published: May 2005

Some parameters which affect the explosibility of dusts have been investigated. Important parameters are particle size, dust concentration, pore size and chemical composition. The dust explosion index measurements illustrate the importance of pore size and particle size. The reaction mechanism occurring is also important. Particles which burn at the solid surface and form gaseous products tend to react completely whereas other materials show a limited transport of the reactants.
An Estimate of Some Statistical Properties of Extinction signals in dilute and concentrated suspensions of monosized spherical particles
Authors: Riebel Ulrich
Published: May 2005

A statistical analysis is made for the extinction of radiations in suspensions, whereby the whole range of possible particle concentrations is covered. The extinction signals are characterized by their average value and by a characteristic length of fluctuation. For simplicity, the considerations are restricted to geometric ray propagation in dispersions of perfectly absorbent, monosized spherical particles. An extinction equation is derived, which reduces to Lambert‐Beer's law in the limit of low particle concentrations. For higher concentrations, significant deviations from Lamberg‐Beer's law due to steric particle‐particle interactions are predicted. The characteristic length of the fluctuations is a function of particle diameter and transmission and has a broad minimum with medium transmissions, allowing for maximum resolution with measurements in this range.
Simultaneous In Situ Measurements of Size and Velocity of burning droplets
Authors: Anders Klaus , Roth Norbert , Frohn Arnold
Published: May 2005

An optical instrument for simultaneous on‐line measurements of the droplet size and droplet velocity of periodically generated droplets is described. This instrument is suitable for studying basic phenomena such as the evaporation or combustion of small droplets and the mutual interaction of neighbouring droplets. For the study of evaporation and combustion rates it is important to have precisely defined initial and boundary conditions. A vibrating‐orifice generator is used to produce monodisperse droplet streams which are characterized by their highly coherent structure. The droplets all have the same size, the same spacing and the same initial velocity. These characteristic parameters of the droplet stream can be adjusted over a wide range as required for the specific experiment. The droplet size is measured with a sizing method of very high accuracy, which evaluates the intensity distribution of the light scattered by the droplets. The droplet diameter ranges from 10 to 150 μm. The droplet velocity is measured by a particle image displacement velocimeter and is compared with conventional LDV measurements. The results of the two methods agree very well. Typical droplet velocities lie in the range from 10 to 20 m/s. Some exemplary experimental results are presented for burning droplet streams, which show the influence of a finite spacing between the droplets on the burning rate.
Anomalous Diffraction Effects in the Sizing of solid particles in liquids
Authors: Brown Dennis J. , Alexander Keith , Cao Jing
Published: May 2005

A study has been made of anomalous diffraction effects in the sizing of solid particles in liquids using a Malvern laser diffraction sizer. The particles were N.B.S. standard reference material 1004 glass spheres. The five liquids used were chosen to give a range of refractive index (R.I.) above and below that of the glass; the ratio of solid R.I. to liquid R.I. (m) ranged from 0.92 to 1.15. Measurements were made of the change in the light energy distribution pattern as the value of | m − 1 | was in creased or reduced towards zero. At high values of | m − 1 | the measured light energy distribution pattern was predicted adequately by the Fraunhofer diffraction approximation to Mie theory and the Fraunhofer computer software could be used to derive particle size distribution from the light energy pattern. For values of | m − 1 | near to zero, the Fraunhofer approach was in error but the anomalous diffraction approximation and software proved adequate for the back‐calculation of size distribution from energy pattern.
Sedimentation of Nonspherical Particles
Authors: Bernhardt Claus
Published: May 2005

The motion of real oblate particles of different cross‐section can be described with sufficient accuracy by equation valid for spheroids. The proof was effected by means of velocity measurements.

The application of theoretical considerations to sedimentation analysis allows it to be used to calculate apparent distributions occurring in the sedimentation of monodisperse particles of uniform shape at any orientation relative to the direction of sedimentation. The transfer to polydisperse systems involves several difficulties, which can be avoided in part by suitable approximations. In the case of a particle system with a polydisperse distribution of a main axis, but a constant particle shape, it is possible to calculate the resulting apparent distributions and their deviations from those distributions obtained when applying the volume equivalent particle diameter.
A Comparative Study on Different Scattering Techniques and data evaluation methods for sizing of colloidal systems using light scattering
Authors: Glatter Otto , Sieberer Johann , Schnablegger Heimo
Published: May 2005

Quasi‐elastic light scattering, elastic light scattering and Fraunhofer diffraction can be used for optical particle sizing. Simulated data were used to compare the different scattering techniques in terms of resolution and range of applicability. Elastic scattering techniques have a ten times higher resolution but cover a smaller size range than quasi‐elastic light scattering. The most important inversion techniques for data evaluation for such experiments were also compared. Regularization techniques with positivity constraints and interpolating cubic B‐splines proved to be superior to truncated singular value decomposition and maximum entropy methods.
Thermal Reactivity of Double‐Base Rocket Propellants
Authors: Pai Verneker V. R. , Kishore K. , Subhas C. B. V.
Published: May 2005

Thermal decomposition studies on double‐base propellants have been carried out in air and vacuum using differential scanning calorimetric, thermogravimetric and mass spectrometric techniques. Low temperature (90 °C–170 °C) decomposition seems to involve diffusion controlled process, the mechanism in air and vacuum being different. High temperature (170 °–205 °C) decomposition involves bond breakage.
Reproducibility of Planewave Transit Times in three explosives during initiation: Comparison to wedge experiments
Authors: Dick J. J. , Engelke R.
Published: May 2005

Planewave transit times were measured in three explosives: PBX‐9404, pressed TNT, and PBX‐9502. Four nominally identical disks were used on each shot to measure the reproducibility of the transit time. Standard deviations in transit times were 1%–2% if most of the wave trajectory was in the initiation phase. The standard deviation in transit times is larger than the measurement precision; this indicates a distribution in the response to the input pressure wave. Comparison was made to results of previous wedge initiation experiments. We conclude that most of the scatter in run distances to detonation found in wedge experiments is not inherent in the initiation process or the explosive quality. The scatter may be due to the imprecision of the free‐surface velocity measurement coupled with the power‐law character of the relation between run distance to detonation and input pressure.
Esters nitriques de polyols. Conformation de la nitroglycérine. Résonance magnétique nucléaire et moment dipolaire
Authors: Lemanceau B. , Caire‐Maurisier M.
Published: May 2005

Le spectre RMN de la nitroglycérine, du type ABCA'B', montre que la molécule est symétrique par rapport au plan HCO passant par le carbone central. Les constantes de couplage protonique peuvent être interprétées par la rigidié du squelette CH2CHCH2 qui se présente alors sous deux conformations possibles telles que deux motifs magnified image contigus soient en position presque éclipsée. Il en est de même pour les groupes CH2ONO2, CHONO2 du dinitrate de propane diol 1–2 et trinitrate de butane triol 1–2–4. Un calcul du moment dipolaire de la nitroglycérine en fonction de la conformation du squelette CH2CHCH2 et de la rotation des groupes NO3 autour des liaisons CO, montre que ce dernier facteur a autant d'importance que le premier. Il ne nous semble donc pas nécessaire de supposer une modification du squelette pour expliquer les variations du moment dipolaire de la nitroglycérine en fonction du solvant.
Brittle Tensile Failure Characteristics of Propellants derived from flexural tests
Authors: Margetson J. , Brokenbrow B. E.
Published: May 2005

The low temperature failure characteristics of two types of solid propellant are derived from the flexural tests on round bar specimens. Quantities which measure strength and variability are established and master curves expressing these quantities in terms of strain rate and temperature are determined. The method is applied to two types of propellants and failure probability contour curves are obtained for each material.
Growth of 1,3,5‐Triamino‐2,4,6,‐Trinitrobenzene (TATB). II. Control of growth by use of high Tg polymeric binders
Authors: Rizzo H. F. , Humphrey J. R. , Kolb J. R.
Published: May 2005

The remarkable safety characteristics of the high explosive 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) are revolutionizing the design and deployment of nuclear weapons. Kel‐F 800 is used as the binder to obtain high‐density, mechanically stable billets of TATB that can be machined into desired shapes. However, repeated thermal cycling between − 54 °C and 74 °C of high density, pure, and plastic‐bonded TATB billets causes a permanent volume expansion (growth) of about 1.5 vol% to 2.0 vol%. Debonding of the Kel‐F 800 binder occurs during growth, causing a reduction in the mechanical properties of the plastic‐bonded explosive. The coefficient of thermal expansion (CTE) of these TATB billets between ambient temperature and 74 °C is 67.0 × 10−6/°C. TATB undergoes a secondary mechanical relaxation just above room temperature, coinciding with the onset of a high CTE, above the glass transition temperature (Tg) of Kel‐F 800. Thus, by judicious selection of a high‐Tg binder, we have essentially eliminated growth, stopped the degradation of mechanical properties after thermal cycling, suppressed the secondary mechanical relaxation, and lowered the CTE to 50.0 × 10−6/°C between ambient temperature and 74 °C.
Predicting High Explosive Detonation Velocities from their composition and structure (II)
Authors: Rothstein L. R.
Published: May 2005

An earlier paper(1) described a simple linear relationship between detonation velocity of 64 ideal C,H,N,O type explosives at their theoretical maximum densities (TMD's) and a factor. F, that is dependent solely upon chemical composition and structure. Based upon available experimental data for nine fluorine‐containing explosives, the equation for calculating the factor has been expanded to include compositional terms for fluorinated compounds. In addition, the reliability of the linear relationship has been further tested against seven more recently published C,H,N,O type explosive experimental detonation velocity data points. The calculated detonation velocity values for all 16 explosives lie within 6.0% of experimental with an absolute error of ± 3.0%.
The ammonium nitrate with 15 WT% potassium nitrate‐ethylenediamine dinitrate‐nitroguanidine system
Authors: Spencer W. , Cady H. H.
Published: May 2005

The phase diagram for the ternary system ammonium nitrate(AN) with 15 wt% potassium nitrate(AN:15KN)‐ethylenediamine dinitrate(EDD)‐nitroguanidine(NQ) has been determined from room temperature to the melting point. The ternary eutectic temperature, measured for a mixture containing 67.24, 25.30, and 7.46 mole% of AN:15KN, EDD, and NQ, respectively, was found to be 98.9 ·°C. The binary phase diagrams for the systems AN:15KN‐EDD, AN:15KN‐NQ, and EDD‐NQ were also determined.
Flame Penetration into Solid Propellant Holes
Authors: Andoh E. , Kubota N.
Published: May 2005

The phenomenon of flame penetration into solid propellant holes has been observed in a nitrogen pressurized strandburner. The phenomenon is largely dependent on the size of the holes, the burning rate (or pressure), and the burned gas temperature. Flame penetration was never observed when the holes were not perforated. The pressure difference between the ends of the hole which is induced by the propellant burning causes the gas to flow into the hole and ignite the interior surface of the hole.
Detonation Properties of 1,3,5‐Triamino‐2,4,6‐Trinitrobenzene when impacted by hypervelocity projectiles
Authors: Delistraty J. , Brandt H.
Published: May 2005

This investigation analyzes the reaction of an insensitive high explosive with binder to hypervelocity impact by four projectiles of two types: rod and plate. The insensitive high explosive is composed of 92.5% 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) and 7.5% Kel‐F 800 binder, a vinylidene fluoride‐chlorotrifluoroethylene copolymer. In this paper, for simplicity, we refer to this composition as “TATB”.

Of the the impacting projectiles, three are steel‐rod assemblies ranging in weight from 32.6 g to 34.6 g, and are composed of a steel rod 8 mm in diameter and 19 mm in length, of which 9 mm protrudes from a Polyzelux plastic holder. The fourth is a tantalum‐plate assembly, weighing 23.9 grams and composed of a tantalum plate 24.2 mm in diameter and 1.5 mm in thickness mounted on a Polyzelux holder. The tantalum‐plate experiment provides a highly efficient diverging detonation profile as predicted by similar previous investigations with flyer plates and TATB. The steel‐rod experiments are compared to the tantalum‐plate experiment to determine if detonation has occurred with the steel‐rod impacts.

The projectiles are accelerated by a two‐stage, light‐gas gun to velocities in the range of 3.1 km/s to 6.5 km/s (10,171 ft/s to 21,325 ft/s) and have bracketed the detonation threshold of the impacted TATB target. Comparisons of the TATB reaction data to a computer modeling of the experiment show that at 3.06 km/s, the computer model correctly predicts no initiation of detonation; at 4.75 km/s, the computer model correctly predicts a partial detonation; and at 5.67 km/s and 6.53 km/s, both the computer analyses and the experiments give divergent detonations.
On the possibility of Detecting Case/Liner and Liner/Propellant Debonds in a Rocket Motor by means of the ultrasonic multiple reflection pulse echo technique
Authors: Zwijnenburg A. , Korting P. A. O. G. , Reitsma H. J.
Published: May 2005

In order to examine whether and to what extent the ultrasonic multiple reflection technique can be used for detecting case/liner and liner/propellant debonds, measurements were performed on samples sawn from a particular case‐bonded rocket motor consisting of a layer of 2.4 mm steel, a layer of 1,3 mm liner material (a polymer) and a thick layer of composite (AP/PU) propellant respectively. It was found that case/liner debonds could be traced reasonably well; liner/propellant debonds, however, could not be evidenced owing to strong quenching of the ultrasound in the liner. Investigations of the texture of the liner material with the aid of a scanning electron microscope proved the strong quenching in the liner to be mainly due to the presence of many voids with diameters of some 50 μm–200 μm which strongly disperse the sound beam.
Factors Influencing the Pyrotechnic Reaction of Silicon and Red Lead
Authors: Hedger J. T.
Published: May 2005

The delay time of a column of pyrotechnic material when used in a delayed action electric detonator is defined as the time between the application of the initiating electrical impulse and the detonation of the explosive charge of the detonator. The effects of fuel/oxidant ratio and fuel surface area on the delay time have been measured for the silicon/red lead system. From the data obtained it has been possible to identify a possible reaction mechanism for this pyrotechnic composition.
Thermal Decomposition of Guanidinium Perchlorate
Authors: Udupa M. R.
Published: May 2005

Thermal decomposition of guanidinium perchlorate has been studied by thermogravimetry, differential thermal analysis, mass spectrometry and X‐ray diffractometry. The title compound undergoes crystallographic phase transformation at 180°C before melting at 255°C. It decomposes exothermally into gaseous products in the temperature range 275°C–325°C. The mass spectral results suggest that the compound undergoes thermal decomposition into neutral particles which are then vapourized, ionized and oxidized. The fragment cyanamide is found to undergo trimerization to give melamine.
On the Break‐Up of Shaped Charge Jets
Authors: Haugstad B.
Published: May 2005

It is shown from dimensional arguments that the semi‐empirical jet break‐up formula of Hirsch(1) is consistent with physical models characterized by ideal plasticity (yield stress σ0), the material initial density (ϱ0), strain rate (η0), and jet radius (r0). Similar arguments applied to a one‐dimensional jet stretching model yields the existence of a maximum unstable perturbation wavelength, and fixes its value to within a numerical constant. Within the class of physical models considered the plastic velocity appearing in the Hirsch formula, the incremental velocity between successive fragments of a particulated jet, and the velocity (σ0/ϱ0)1/2 are all related, as originally conjectured by Hirsch.
Application of the Robbins‐Monro method to the sensitivity testing of explosives. II. The experimental practice
Authors: Schilperoord A. A. , Bruckman H. W. L. , Schelling B. A.
Published: May 2005

In this second part of a series of publications dealing with the application of the Robbins‐Monro method to the sensitivity testing of explosives, the experimental aspects are treated. The results of an experimental program with a primer drop‐test apparatus confirmed the efficiency which was concluded from the computer simulation study, also for extreme percentage points. Further a method is described to determine the reliability of the outcome after the execution of the Robbins‐Monro process. It is shown that for an efficient application of the Robbins‐Monro method the level distance which can be adjusted should be about 1/2 to 1/3 of the standard deviation (of a normal distribution) dependent on the percentage point.
Explosives Performance Potential ‐ A New Definition
Authors: Krishna Mohan V. , Tang Tong B.
Published: May 2005

A new method for predicting explosive performance potential is suggested. This parameter, which has the dimension of power density, can be theoretically evaluated from three readily available quantities, as the product of the cube root of the volume ratio of detonation products to reactant, heat of detonation, and detonation velocity of the explosive. The calculated performance potential has been found to correlate well with the strength and brisance data for a number of explosives. Experimental detonation pressure gives equally satisfactory correlation; since its measurement is difficult, the approach advocated here is preferable.
Low Pressure Combustion of Composite Propellant
Authors: Schöyer H. F. R. , Korting P. A. O. G.
Published: May 2005

The combustion behaviour of two batches of a new type of composite propellant was investigated in the pressure range between 5 kPa and 915 kPa absolute. A newly developed technique to determine simultaneously the burning rate, combustion efficiency, and the propellant's sensitivity for combustion instability is described together with a specially developed data reduction code. Notwithstanding the low pressure during the experiments no lower deflagration limit could be traced but a Vieille type burning rate law appeared to be applicable for the whole pressure range of interest. A large difference found in the combustion behaviour could be attributed to the fact that the two batches had been manufactured with AP from different suppliers. Combustion efficiency was poor while combustion instability occurred in the whole pressure range.
The Characteristic Temperature Method to Estimate Kinetic Parameters from DTA curves and to evaluate the compatibility of explosives
Authors: Liu Z. R. , Yin C. M. , Wu C. H. Y. , Chang M. N.
Published: May 2005

The thermal analysis technique was used to rapidly evaluate the compatibility of explosives with contacted materials. The three kinetic parameters viz. activation energy E, reaction order n and pre‐exponential factor A were calculated from three characteristic temperatures of a single DTA curve. The compatibility was evaluated from the four parameters E, n and the characteristic temperatures Tm (peak maximum) and To (decomposition starting point on the DTA curve). The results are compared to those obtained from the gasometric method.
Sintox ‐ A New, Non‐Toxic Primer Composition by Dynamit Nobel AG
Authors: Hagel R. , Redecker K.
Published: May 2005

A general development of proven composition variants is derived from the historical evolution of primer compositions. Rules and requirements for new developments can be drawn up. On the basis of this knowledge the concept of a primer mixture, containing non‐toxic elements is laid down. An analysis of the air in firing ranges enables a comparison of the emission behaviour of conventional sinoxide ammunition and the new sintox ammunition. (Sintox is a protected trade‐mark (brand name) of Dynamit Nobel AG.)
Decomposition Chemistry of TAGN
Authors: Kubota Naminosuke , Hirata Norimasa , Sakamoto Satoshi
Published: May 2005

Triaminoguanidine nitrate (TAGN) is a unique energetic material which produces relatively low molecular weight combustion products. TAGN is characterized by the oxidizer fragment “HNO3” that is attached by an ionic bond in the molecular structure. In this study, various types of experiments were conducted in order to elucidate the physicochemical decomposition process of TAGN. The exothermic rapid reaction observed at the early stage of the decomposition is the process representing the nature of energetics of TAGN. This exothermic reaction occurs immediately after the endothermic phase change from solid to liquid. Since the weakest chemical bond consisting in the TAGN molecule is the NN bond (159 kJ/mol), the initial bond breakage should be the amino groups and the NH2 radicals split off. The energy released by the dissociation of the NH2 radicals (104.3 kJ/mol) is the heat produced at the early stage decomposition of TAGN. Thus, the burning rate of TAGN is considered to be dominated by the dissociation of the NH2 radicals. It must be noted that the burning rate of TAGN is almost double that of HMX even though the energy contained in the unit mass of TAGN is less than that of HMX. The HNO3 attached to the molecular structure of TAGN is not the fragment to produce the exothermic rapid reaction observed at the early stage decomposition process.
Thermal Decomposition of Energetic Materials XXVIII. Predictions and results for nitramines of bis‐imidazolidinedione: DINGU, TNGU and TDCD
Authors: Oyumi Y. , Brill T. B.
Published: May 2005

Structural/thermal decomposition relationships are assessed in this project. The relative concentrations of the first observed, infrared‐active gas products generated by fast thermolysis (dT/dt = 110 K/s) of 2,5‐dioxo‐1,3,4,6‐tetranitro‐tetrahydrocyclobutan[1,2‐d : 3,4‐d′]diimidazole (TDCD) and 1,3,4,6‐tetranitroglycoluril (TNGU) were successfully predictable from structure/thermal decomposition relationships. The predictions for 1,4‐dinitroglycoluril (DINGU) were only partly successful. The departures from expection appear to originate from the different degree of stability of the non‐energetic backbone of these molecules. The dependence of the first‐observed gas products on pressure from these molecules was qualitatively predicted from the nature of the products liberated at atmospheric pressure.
Critical energy criterion for the Initiation of Explosives by Spherical Projectiles
Authors: James H. R. , Hewitt D. B.
Published: May 2005

Evidence is given of a fundamental difference between the response of bare explosive to the impact of a flat‐nosed rod, and the response to a sphere or round‐nosed rod. For relatively insensitive explosives such as Composition B, a spherical projectile, in contrast to a flat‐nosed rod, can have a range of impact velocities that produce a blast output which falls short of the output expected from a full detonation. It is postulated that this effect is caused by the divergent flow behind the initial impact shock created by the sphere. Without such divergence it is assumed that these impacts would produce full detonation. Consequently thc critical energy criterion for spherical impacts should be applied to the non‐reaction/reaction boundary and not the reaction/detonation boundary. This is shown to give constant values of critical energy for different sizes of sphere impacting the same explosive, and to give similar energy values to those obtained from impacts of flat‐nosed rods.
A rapid non‐aqueous titrimetric estimation of ammonium perchlorate in pyrotechnic compositions
Authors: Ninan K. N. , Madhavan A. , Sadhana R.
Published: May 2005

A rapid and safe nonaqueous titrimetric method has been developed for the estimation of ammonium perchlorate (AP) in pyrotechnic compositions. It uses tetrabutyl ammonium hydroxide as titrant and dimethyl formamide, pyridine or dimethyl sulfoxide as solvent. The validity of the method has been confirmed using pure AP and AP mixed with known quantities of aluminium, zirconium or boron. Both visual (thymol blue indicator) and potentiometric methods are employed in the estimation.
Study on the Mechanism of the Acetolysis of Hexamethylenetetramine
Authors: Ju Chen , Shaofang Wang , Fuping Li
Published: May 2005

The acetolysis of hexamethylenetetramine (hexamine) to give 3,7‐diacetyl‐1,3,5,7‐tetraaza‐[3.3.1]‐bicyclononane (DAPT), 1,3,5,7‐tetraacetyl‐1,3,5,7‐tetraazacyclooctane (TAT) and 1,3,5‐triacetyl‐1,3,5‐triazacyclohexane (TRAT) was studied. NMR tracing showed the courses of acetolysis, the effects of the reaction conditions on its directions, and the evidence that the methylene degraded from hexamine was the formaldehyde. Based on these results, the acetolysis mechanism was proposed. The comparison of the acetolysis with the nitrolysis of hexamine showed that the two reactions experienced the similar courses, which would be useful for searching out a way to improve the yield of 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX) in Bachmann process.
Investigation of Liquid Gun Propellants: Electrical ignition of LGP 1846
Authors: Klingenberg G. , Rockstroh H. , Knapton J. D. , Despirito J. , Frieske H.‐J.
Published: May 2005

Progress achieved in the study of the electrical ignition of the hydroxylammonium nitrate(HAN)‐based liquid gun propellant LGP 1846 is described. The goal of the work is to develop an igniter system suitable for regenerative liquid propellant guns. Several igniter configurations of the one‐ as well as the two‐stage types designed by the Ballistic Research Laboratory and the Fraunhofer‐Institut EMI‐AFB, have been tested. Voltage and current as well as the pressure histories were recorded. Calculations of electrostatic field distributions discussed here were obtained by a finite element code implemented at Dynamit Nobel. The theoretical analysis yielded alternative electrode designs for future testing. In addition, a specially designed igniter chamber equipped with sapphire windows was used at EMJ‐AFB to study the fundamentals of the electrical discharge by means of high‐speed photography.
Correlations between Reaction Dynamics Experiments and the Detonation of Explosives
Authors: Walker Franklin E.
Published: May 2005

Data and information reported from reaction dynamics experiments appear to correlate very well with data and calculations from the detonation of chemical explosives. Comparisons are presented of particle and vibratiional velocities, atomic and molecular kinetic energics, time scales for reaction, bond strengths, and shock velocity data. A rationale and method for determining detonation velocities and evidence for rate‐determining kinetics from the reaction dynamics data and molecular dynamics calculations are presented. It is concluded that first order values for detonation characteristics can be calculated from the energy and reaction rate factors considered, and that the methods of reaction dynamics discussed could be applied to the study of probable detonation reactions to give refined quantitative values for detonation processes.
Isomer distribution of nitro derivatives of diphenylamine in gun propellants: Nitrosamine Chemistry
Authors: Curtis Neville J.
Published: May 2005

The derivatisation of diphenylamine (DPA) in single base gun propellants was studied as a function of aging at 80°C. The relative proportions of 2‐nitro DPA and 4‐nitro DPA varied from 32 : 68 to 63 : 37 according to propellant type. Preferences for para substitution were seen in experimental lots “stabilized” with 2‐nitroDPA, 4‐nitroDPA and N‐nitrosoDPA. Increasing water content resulted in higher preferences for ortho substitution. 4‐NitroDPA is a better stabilizer than 2‐nitroDPA. Model studies performed using nitro substituted N‐nitrosamines show that para substitution is preferred in boiling acetic acid. Mechanisms for the conversion of N‐nitrosamines into isomeric nitro derivatives are discussed with relation to the model studies and the behaviour in propellants. Detailed experimental procedures are given for the preparation of N‐nitrosamines.
Uncontrolled ignition mechanisms in liquid propellant guns
Authors: Knapton John D. , Coffee Terence P.
Published: May 2005

Two potential mechanisms are described which may result in uncontrolled ignition in liquid propellant regenerative guns. The two mechanisms are related to reverse burn in the injection orifice. One mechanism is associated with a poorly designed injection orifice, which may result in a low discharge coefficient, boundary layer separation, and flame holding in the orifice. The second mechanism is related to the response of the liquid propellant reservoir to the ignition pressure, which may excite pressure oscillations in the reservoir resulting in a reverse orifice pressure gradient. Both mechanisms may result in a reverse orifice burn or flash back to the reservoir.
Ignition Mechanisms in Monopropellants
Authors: Messina Neale A. , Ingram Larry S. , Tarczynski Marek , Knapton John D.
Published: May 2005

The sensitivity of liquid monopropellants is examined when subjected to compression ignition, including the case of purposeful sensitization with air bubbles; and frictional heating. The monopropellant is a hydroxylammonium nitrate (HAN)‐based propellant. Conditions are identified which will likely result in ignition from rapid compression. Ignition from frictional heating associated with hydroynamic flow is less certain, however attempts to model this phenomenon theoretically have been made.