bluuebunny/crossref_metadata_2025 huggingface dataset:
Miscibility of polyamide‐6 and polystyrene functionalized with sulfonic acid groups
Authors: Molnár Attila , Eisenberg Adi
Published: December 2004

Polyamide‐6 (PA‐6) and sulfonated polystyrene (SPS) interact strongly in solution. Thus, solution blends of PA‐6 and SPS (sulfonation levels from 0 to 12.3 mol%) in m‐cresol form clear, hazy, or gelled solutions–depending on the ratio of amide (A) to sulfonic acid (S) groups (A/S). NMR studies show that the S groups interact with the nitrogen of the amides, most probably through the transfer of the sulfonic acid protons. During melt blending, the addition of SPS to the PA‐6 leads to a torque rise because of strong interactions. The glass transition temperatures of the components in the melt blended samples shift towards each other as the sulfonation level of the SPS increases, indicating enhanced miscibility. The analysis of the extracted PA‐6 from thee blends, however, shows that it is degraded at processing temperatures (250°C), owing to some residual water and the catalytic activity of the sulfonic acid groups. The extent of the PA‐6 degradation is inversely related to the A/S ratio. Each sulfonic acid group causes between one and two chain scissions of the PA‐6. In blends with high A/S ratios, the degradation of the PA‐6 is minimal; yet considerable dispersion of the SPS can be achieved, as evidenced by scanning electron micrographs of the fracture surfaces.
Experimental investigation of the drag flow assumption in extruder analysis
Authors: Campbell G. A. , Sweeney P. A. , Felton J. N.
Published: December 2004

A new screw pump or extruder has been constructed with the goal of testing the drag flow analysis currently used in the evaluation of polymeric extruders. The new device has been constructed in a manner that allows the barrel, screw helix, and screw core to be rotated independently or in pairs. The experimental results of the flow produced for rotation of the barrel agree well with the theory. However, the flow produced by rotation of the screw elements does not agree with the predictions of the currently accepted theory. The experimental results indicate that the primary element that produced fluid propulsion when the screw is rotated is the screw helix. A new qualitative theory is proposed that is in agreement with the data.
Analysis of isothermal two‐layer blown film coextrusion
Authors: Yoon K.‐S. , Park C.‐W.
Published: December 2004

The mechanics of a bicomponent two‐layer blown film coextrusion is studied theoretically. As a first step for the modeling of this complex process, we adopt a simple system in which the flow is assumed to be isothermal and the two layers are a Newtonian and an upper‐convected Maxwell fluid (UCM), respectively. The two fluids are chosen to investigate the relative influence of viscous and viscoelastic forces on the flow mechanics of the process. For a given total flow rate, blow‐up ratio, freeze‐line height, and film gage, the radius and the melt thickness profiles of the blown film are determined numerically for various values of the flow rate ratio of the two fluids. When the relaxation time of the UCM layer is small, the flow mechanics including the shape of the bubble (or the radius profile) is not much different from that of a Newtonian single‐layer flow. With increasing relaxation time, the viscoelasticity effect of the UCM layer becomes more and more pronounced and eventually dominates the bubble dynamics even though its layer thickness may be smaller than that of the Newtonian layer.
Properties of a thermotropic liquid crystalline polymer blended with different thermoplastics
Authors: Chapleau Nathalie , Carreau Pierre J. , Peleteiro Carmen , Lavoie Paul‐André , Malik Tariq M.
Published: December 2004

Thermal, rheological, morphological, and mechanical properties of a thermotropic liquid crystalline polymer, TLCP (copolyester Vectra A‐950 from Hoechst), blended with a polycarbonate (PC), a polyethylene glycol terephthalate (PETG), and a blend of PC and PETG (20/80) are presented and discussed. Important supercooling effects are observed for the TLCP. For the blends the glass transition temperature of the matrix is shown to decrease slightly, suggesting partial miscibility of the components. A finer dispersion is observed for the TLCP/PC blends, at least for TLCP concentrations lower than 20%, for which the mechanical properties are quite good. For higher TLCP concentrations, as well as for the other two matrices, the mechanical properties follow more or less the mixing rule, and the morphology of the blends suggests poor adhesion. We were unable to obtain fibrillar structures by extruding the blends through a capillary rheometer; in the TLCP/PC blends, the TLCP domains were too small, and for the other blends the extrudates had not enough melt strength.
Internal friction in two longitudinal polymer liquid crystal esters
Authors: Brostow Witold , Samatowicz Danuta
Published: December 2004

Internal friction (IF) was measured for two polymer liquid crystal (PLC) esters, PET/xPHB, where PET is poly(ethylene terephthalate), PHB is p‐hydroxybenzoic acid, with the mole fractions x of the PHB in the copolymers 0.5 and 0.6. Pure PET was also studied for comparison. The internal friction parameter Q−1 and the square of the output vibration frequency ƒ2 were determined as a function of temperature between −150°C and +400°C for a fixed input frequency. Values of the latter were varied between 0.5 and 30 Hz; all spectra were recorded under vacuum of 0.10 Torr. The IF results are virtually independent of the substrate used, namely silica glass or platinum. Multiple transitions found in each sample agree fairly well with those determined by other methods, including thermally stimulated depolarization. In contrast to other dynamic mechanical methods, a single internal friction vs. temperature run can be used to locate transitions in solid as well as in melt phases.
Modeling of the conveying of solid polymer in the feeding zone of intermeshing co‐rotating twin screw extruders
Authors: Carrot C. , Guillet J. , May J. F. , Puaux J. P.
Published: December 2004

In this paper, a model for the conveying of solid polymer in the feeding zone of intermeshing co‐rotating twin screw extruders is proposed. The theoretical model uses an approach that is similar to that commonly used in single screw extruders; however, it takes into account the particular geometry of the screw channel, the partially filled channel, and the special configuration of the two self‐wiping screws. The model thus considers two conveying mechanisms: the first one in the channel, which is analyzed in terms of polymer‐metal friction, and the second one, which is mainly an axial transport in the intermeshing zone. The theoretical predictions of the model are compared with the experimental results obtained on a laboratory extruder with a polymer in powder form, and satisfactory agreement is observed. The model enables the prediction of the evolution of the filling of the screws towards the geometry and the operating conditions. This is an important key to analyzing the thermal aspects in this zone, which can lead to a prediction of the melting capacity of the extruder. Indeed, the filling of the feeding zone defines the heat transport that occurs between the hot barrel and the solid polymer.
Modeling fountain flow and filling front shape in reaction injection molding
Authors: Perrett F. J. , Reible D. D. , McIlhenny R. C.
Published: December 2004

A numerical model of the reaction injection molding process was developed to test front shape and flow approximations employed in previous models. The model was two‐dimensional and simulated the flow, reaction, and heat transfer in the typically long axial dimension and the typically small thickness dimension of a mold. The filling front shape and the velocity profiles in the filling fluid were determined by numerical solution of the momentum equation with the appropriate stress boundary conditions using the method of Patankar (1980). The predicted temperature and conversion results agreed with calculations assuming that the front was flat perpendicular to the flow and that a parabolic velocity profile existed behind the fountain flow region at the front. Thus, simple assumptions about front shape and velocity in the thin dimension of a reaction injection mold can be employed without significant loss of accuracy in modeling reaction injection molding.
Structure and properties of nylon 6 modified by γ‐irradiated linear low density polyethylene
Authors: Valenza A. , Spadaro G. , Calderaro E. , Acierno D.
Published: December 2004

In this work, structure and properties of blends of nylon 6 with 10% linear low density polyethylene γ‐irradiated in air at different integrated doses are presented. More particularly, Molau tests, DSC, SEM, and mechanical tests have been performed. Results show that positive morphological changes with respect to the blend with unirradiated linear low density polyethylene are well evident, especially in the blend with polyethylene irradiated at 50 KGy. This blend also shows an enhancement of the elongation at break and of the impact properties.
Fatigue behavior of medium‐density polyethylene pipes for gas distribution
Authors: Nishimura Hiroyuki , Nakashiba Akio , Nakakura Masahiro , Sasai Kunihiro
Published: December 2004

This paper illustrates the factors that control brittle failure under fatigue loading for test specimens cut from medium‐density polyethylene pipes for gas distribution. A square bar specimen cut from a pipe with a notch was made and a fatigue test was conducted to cause a brittle failure. To obtain the correlation among stress range, frequency, temperature, and cycles to failure in this fatigue test, Coffin‐Manson's frequency‐modified fatigue life equation was adopted and the material constants were determined. By gradually lowering the frequency, the resistance to creep can be estimated because cycles to failure—indicating the fatigue damage—decreased, and the actual loading time—indicating the creep damage—increased.
The role of the fibrillar structures in the compressive behavior of rigid‐rod polymeric fibers
Authors: Lee Charles Y.‐C. , Santhosh U.
Published: December 2004

The buckling of a fiber with a fibrillar microstructure is examined in light of all possible buckling modes. Parametric studies are done at variously assumed morphological levels, from a fibril down to a molecular chain, and it is shown that the buckling mode could, be different depending on the dimensional level of the individual buckling unit and the degree of interaction between the buckling elements. It is argued that fibrillar, instability is the principal reason for the low compressive strength of rigid‐rod polymeric fibers, and alternative approaches to improve the degree of interaction between the fibrils are considered.
Compatibilizing agents in polymer blends: Interfacial tension, phase morphology, and mechanical properties
Authors: Chen Cheng Chung , White James L.
Published: December 2004

The interfacial tension, phase morphology, and phase growth was determined for four polymer blend systems: polyethylene/polystyrene, polyethylene/polyamide‐6, polystyrene/polyamide‐6, and polystyrene/poly(ethylene terephthalate). Generally, high interfacial tension correlates with coarse phase morphology and rapid phase coalescence. The addition of various potential compatibilizing agents to these binary blend systems results in lowered interfacial tension, finer and stabilized phase morphologies. The characteristics of different compatibilizing agents were compared for several of the blend systems. We also look at the influences of compatibilizing agents on mechanical properties of the blend systems. Some compatibilizing agents are able to produce substantial improvements in ultimate properties.
Rheological behavior of a semirigid liquid crystal polymer
Authors: La Mantia F. P. , Valenza A. , Paci M. , Magagnini P. L. , Pedretti U. , Roggero A.
Published: December 2004

The rheological behavior of liquid crystal polymers is still far from completely clarified from both experimental and theoretical points of view. In this paper, the shear flow and the non‐isothermal elongation flow behavior of a semirigid liquid crystal copolyester is discussed. The viscosity strongly decreases when the test temperature is increased above the crystal‐nematic transition temperature; below this temperature the viscosity is very high. The thermal history strongly affects the shear viscosity. The elongational flow behavior depends also on temperature. Above the crystal‐nematic transition temperature and the mesophase is easily spinnable, whereas below this temperature, the spinnability is very poor.
Spin coating behavior of polyimide precursor solutions
Authors: Levinson William A. , Arnold Anthony , Dehodgins Ofelia
Published: December 2004

Experimental data confirm the utility of the following simple equation in predicting the spin coating behavior of polyimide precursor solutions:

in which

.
The dielectric behavior of glassy amorphous polymers at 2.45 GHz
Authors: Chen M. , Siochi E. J. , Ward T. C. , McGrath J. E.
Published: December 2004

The dielectric behavior of glassy thermoplastic polymer in the microwave frequency range was investigated. Specifically, the relationship between energy absorption and temperature for several thermoplastic systems was examined to test the theoretical basis for heating under microwave irradiation. Irradiation under traveling and standing wave conditions were explored. The heating rate versus temperature data at a frequency of 2.45 GHz yielded a microwave calorimetry procedure for examination of the dielectric and relaxation behaviors. Correlations were drawn between (a) the apparent activation energy and the critical temperature, and (b) the shape of the dielectric spectra at 2.45 GHz and its shape in the kHz region. WLF relationships were examined for glassy thermoplastics to show the difference in changing activation energy with temperature.
Viscoelastic properties of a styrene‐isoprene‐styrene triblock copolymer and its blends with polyisoprene homopolymer and styrene‐isoprene diblock copolymer
Authors: Berglund Charles A. , McKay Kevin W.
Published: December 2004

The effects of added polyisoprene homopolymer (PI) and polyisoprene‐blockstyrene diblock copolymer (SI) on the viscoelastic properties of a polystyrene‐block‐polyisoprene‐block‐polystyrene triblock copolymer (SIS) having a spherical domain morphology have been examined. The former two species are used to model the effects of imperfections in structures that result from triblock copolymers missing, respectively, two or one polystyrene end blocks. The results indicate that the loss modulus and tangent delta in the plateau region can be dominated by imperfections in the copolymer structure. The interpretation of viscoelastic data in the rubbery plateau region as an indication of interface structure in block copolymers is therefore greatly complicated. Small angle X‐ray scattering (SAXS) and rheological tests were also used to determine the order‐disorder transition temperature for an SIS triblock copolymer and its blend with an SI diblock. The SAXS data are consistent with Han's rheological criteria for determining the order‐disorder transition temperature. However, the complex viscosity does exhibit Newtonian behavior for low rates at the highest temperatures, even though the domain morphology persists. Stress relaxation and dynamic modulus data at high temperatures clearly show a secondary “rubbery” plateau at long times, and we offer a qualitative explanation for this feature based on a proposed relaxation mechanism.
Process of unsaturated polyester resin synthesis on a laboratory and industrial scale
Authors: Korbar J. , Golob J. , Šebenik A.
Published: December 2004

A study of the progress of the synthesis of unsaturated polyesters, based on anhydrides of phthalic and maleic acid and propylene glycol without added catalysts was done. The reaction was carried out on a laboratory and industrial scale. The acid number and molecular weight distribution were determined. In the laboratory synthesis the, amount of water produced during the reaction was also measured. Two steps in the reactions were observed. The first is the reaction of anhydrides with glycol producing monoester which is followed by step‐growth polymerization reaction producing polymer. The kinetics of step‐growth polymerization reaction was found to be third order with an activation energy of Ea = 54.3 kJ mol−1 and ko = 15.2 kg2mol−2s−1. The kinetic model was prepared and compared with results obtained from reactions carried out on an industrial scale. A method is presented for determining a heating program based on a limited reaction rate and a maximal reaction temperature for a particular system. The MWD of polyester resin was determined and disagreement was found compared to the “most probable” MWD.
Boundary element study on particle orientation caused by the fountain flow in injection molding
Authors: Jin Xiaoshi
Published: December 2004

A boundary element model is used for simulating the fountain flow in injection molding. The particle orientation caused by the fountain effect is illustrated with a tracer‐in‐domain technique which is similar to the Marker‐And‐Cell technique. The efficiency and accuracy of the boundary element model are shown through this simulation, in determination of the free surface shape, and the particle orientation patterns. Clear and correct information is obtained to interpret the complicated effects upon formation of the orientation, especially regarding the “V” shape pattern in the skin areas. The simulation is in agreement with both Schmidt's experiment and some finite element analysis.
Design and processing optimization of extruder screws
Authors: Potente H. , Hanhart W. , Reski T.
Published: December 2004

Only recently has increasing use been made of computer simulation in the field of extruder engineering. This simulation is based on physico‐mathematical process models. In order to achieve a closed, process engineering‐based extruder layout and operating behavior simulation it is necessary to have models describing the throughput behavior, the melting process, the temperature development, the pressure profile over the screw length, the residence time distribution, the mixing and dispersion processes, and also the torque and power requirements. In the Plastics Technology Section of the University of Paderborn (KTP) a program for the computer‐aided design of extruders (REX), financed by 17 companies, was developed which will permit rapid application of the models developed there and will fulfill the requirements set out above. Since no computation‐intensive numerical methods like Finite Element or Finite Difference Methods (FEM, FDM) are required, the algorithms are very rapid, which means that short computing times are achieved (just a few seconds on an IBM AT).
Crosslinking in halogen containing novolac electron beam negative resists
Authors: Lampe I. V. , Reinhardt M.
Published: December 2004

Halogenophenol novolac (HPN)‐based negative resists exhibit excellent sensitivity and pattern resolution properties. The HPNs act as synergists for crosslinking with other irradiation labile compounds such as naphthoquinone diazide and bisazide vs. hydrogen halide (HX) elimination reaction, resulting in additional crosslinking, probably by aryl radical recombination and/or addition. We describe a new resist formulation based on HPN binder and melamine crosslinker (Cymel 303). In this case the irradiation induced HX elimination additionally catalyzes the melamine crosslinking.
Rheology of thermoplastic starch: Effects of temperature, moisture content, and additives on melt viscosity
Authors: Willett J. L. , Jasberg B. K. , Swanson C. L.
Published: December 2004

The melt viscosity of thermoplastic starch has been investigated as a function of temperature, moisture content, and processing conditions. The effects of various low molecular weight additives have also been studied. Starch melts exhibit power law behavior over the range of shear rates studied. Melt viscosity decreased with increasing temperature and moisture content (MC). The power law index m increased with increasing temperature. The consistency K decreased with increasing temperature and increasing moisture content. Moisture content during the pelletizing step influenced melt viscosities measured after equilibration to different MCs. All additives studied except glycerol monostearate (GMS) significantly lowered the melt viscosity of starch, some more effectively than water relative to starch with 15% MC. Starch with GMS had viscosities essentially the same as, or slightly higher than, starch/water. This behavior may be due to the presence of unmelted helical inclusion complexes of starch and GMS. Starch formulations at 160°C exhibited melt visocosities similar to an LDPE of melt index 1.8.
On the phenomenology of yield in bisphenol‐a polycarbonate
Authors: Stokes Vijay K. , Bushko Wit C.
Published: December 2004

The phenomenology of yield in bisphenol‐A polycarbonate is explored through tensile tests on thin rectangular specimens and through pressure‐induced bulging of thin, clamped circular disks. In a tensile test, while the nominal critical stress at which yield initiates and the nominal draw stress at which a stable neck propagates along a specimen depend on the temperature and the strain rate, the ratio of the draw stress to the critical stress is shown to be approximately 0.75 over a temperature range of 22 to 65°C and strain‐rates in the range of 10−4 to 100 s−1. Specimens subjected to constant tensile loads between the draw and critical stresses are shown first to creep till stretches on the order of 1.06 are attained and then are shown to undergo stable necking. Tensile tests on thin, wide rectangular specimens show that yielding initiates through shear bands that broaden and intersect to generate necks, which subsequently propagate along the specimen. In pressure‐induced bulging of clamped disks, biaxial stretching progresses monotonically under increasing pressures; strain localization does occur near the outer edges of the specimens, however. Heating of a specimen with a substantial stably necked region shows that the temperature‐induced recovery of the specimen from its deformed state begins well below the transition temperature Tg of the material, although most of the recovery occurs at Tg.
Extrusion die design for multiple stripes
Authors: Wen Shu‐Heng , Liu Ta‐Jo
Published: December 2004

Two numerical approaches have been applied to examine the possibility of adding shims to conventional extrusion dies such as T‐dies and coat‐hanger dies to produce multiple stripes. The first numerical approach is based on a one or two‐dimensional lubrication approximation and the second one is the three‐dimensional finite element simulation. Both approaches are applicable, but the lubrication approximation is accurate and much simpler to use. The extruded stripes are assumed to obey a non‐Newtonian power‐law model. It has been found that the T‐die with a shim can produce multiple stripes of acceptable uniformity, irrespective of the strip numbers and widths and the power‐law index. The coat‐hanger die with a shim did not deliver multiple stripes with good uniformity. Adding an outer manifold to the coat‐hanger die can serve as an effective means to reduce flow nonuniformities.
A cure study on alumina trihydrate reinforced allylester resins by differential scanning calorimetry
Authors: Jang Jyongsik , Yi Jieun
Published: December 2004

Allylester prepolymers were synthesized by transesterification, and curing kinetics of alumina tihydrate reinforced allylester resins was studied by means of a differential scanning calorimetry dynamic experiment. The activation energies and the frequency factors of the reinforced allylester prepolymers were estimated by means of Ozawa's and Kissinger's methods. The values determined from the Ozawa method are higher than those from the Kissinger method. The peak exotherm temperature of reinforced allylester resin was shifted to a lower temperature as the concentration of curing agent increased. The peak exotherm temperature as the concentration of curing agent increased. The peak exotherm temperature of reinforced allylester resin was, however, shifted to a higher temperature as the content of alumina trihydrate increased. In the case of the dynamic experiment, both the activation energy and the frequency factor decreased as the concentration of curing agent was increased. Meanwhile, there exist minimum values of both the activation energy and th frequency factor with varying contents of alumina trihydrate.
Rheological study on poly‐D(‐)(3‐hydroxybutyrate) and its blends with poly(ethylene oxide)
Authors: Choi H. J. , Park S. H. , Yoon J. S. , Lee H‐S. , Choi S. J.
Published: December 2004

Aspects of thermal, morphological, and rheological properties of biodegradable poly‐D(‐)(3‐hydeoxybutyrate) (PHB) blended with poly(ethylene oxide) (PEO) have been studied. Thermal properties and morphology of the blends were examined by scanning electron microscopy and differential scanning calorimetry, respectively. A rotational theometer with parallel plate geometry was also adopted to investigate the rheological properties of these blends. In addition, dynamic ciscoelasticity was measured by a Rheovibron as functions of time and temperature. From these measurements, PHB and PEO were observed to be miscible in the melt state. In the case of the blend systen 80/20 PHB/PEO by weight, the vacant domains of the PHB were filled with PEO particles, and this morphological state enhanced the rheological properties. Furthermore, PHB and its blends were found to have high crystallinities, but to have unstable thermal behavior about Tm.
Low shear viscosity and crystallization in dilute solutions of polymers at high pressures: Falling body viscometry of high molecular weight polyethylene solutions
Authors: Akki Rashi , Bair Scott , Abhiraman A. S.
Published: December 2004

A specially designed falling body viscometer has been used to obtain low shear viscosities of dilute solutions of high molecular weight polyethylene in decalin and for detecting phase transitions at high pressures. The method provides valuable rheological data at pressures that correspond to those I lubrication and some extrusion processes. In addition, the method enables detection of phase transitions, such as crystallization, that result in detectable changes in rheology. The influence of pressure as high as 0.6 GPa ( ∼ 80.000 psi) is illustrated here through a study of crystallization, with verification from light scattering and calorimetry.
Modeling the mechanical properties in polypropylene/polyamide‐6 blends with core shell morphology
Authors: Rösch Jocachim
Published: December 2004

Polypropylene/Polyamide‐6 (PP.PA) blends containing maleic anhydride grafted elastomers were prepared by reactive blending. Three different types of core shell morphologies were obtained and characterized by transmission electron microscopy (TEM). The midulus of these elastomer midified PP/PA (70/30) blends with core shell type morphology is compared to predictions derived from the Kerner model. The multiphase morphology of these blends could be modeled by sequential application of the Kerner equation to two‐phase subinclusions. Using morphological data ontained by TEM, good agreement between experimental and calculated values was ontained. The results are used to tailor PP/Pa‐6 blends combining stiffness and toughness.
Application of the Virial Equation of State in calculating interior ballistics quantities
Authors: Volk F. , Bathelt H.
Published: December 2004

In calculating interior ballistics quantities the virial equation state is applied as an equation of state for real gases. A method shown of calculating the second and third virial coefficients for and mixtures of gases by using potential functions. A FORTRAN program has been set up for these calculations.
The Quantity/Distance Category of Gun and Rocket Propellants
Authors: Bascombe K. N. , Wyatt R. M. H.
Published: December 2004

The quantity/distance categorisation of explosive materials is discussed. The procedure for the standard UK laboratory‐type test (large sealed vessel test) is described. The borderline, in terms of the test, between fire and explosive risks has been established by testing materials for which the nature of the hazard is previously known. Trials have established that boxed UK plastic (composite) propellants are fire risks only.
The Influence of Additives on Pressure and Momentum of the Air Shock from detonating charges
Authors: Licht H. H. , Froböse M.
Published: December 2004

The air blast effect produced by high explosives with additives of various types and quantities was studied. To this end, air shock intensities and pressure profiles were recorded at certain distances from an unconfined charge. Among those additives which by their reaction with the gaseous products of the detonated explosive theoretically should increase the energy potential, aluminum and zirconium exhibit a positive effect while other substances such as boron react too slowly for strengthening the blast effect. An addition of aluminum (32 weight%) causes the shock wave pressure to increase by about 15% and the momentum by 30% as compared with the pure explosive.
CTPB Cure Studies‐effect of experimental variables on epoxide cure and properties of gumstocks
Authors: McGuchan R. , Spickernell G. J.
Published: December 2004

The effects of various processing and compositional variables the cure rate and mechanical properties of epoxide‐cured CTPB gumstocks have been evaluated.

Viscosity changes during the initial stages of cure and tensile properties of fully cured gumstocks are sensitive to the nature and functionality of the epoxide curative even though comparisons are made at epoxy/carboxyl equivalence ratios giving the same density of crosslinks. Batch‐to‐batch variations in prepolymer structure, functionality and impurities also are important. In particular, glutaric acid impurity inhibits the cure, the effect being very marked when the mixing procedure involves heating the prepolymer and catalyst together before the addition of epoxide.

Effects due to plasticisers and ammonium perchlorate filler also are reported. The mechanical behaviour of gumstocks and of corresponding filled systems (propellants) show little correlation.
New Aspects in Ferroelectric Energy Sources for Impact Fuzes
Authors: Bauer F. , Vollrath K.
Published: December 2004

In order to find materials with increased specific electrical energy, especially for impact fuzes, the irreversible conversion of mechanical to electrical energy in ferroelectric ceramics of the Pb(Zr1‐xTix) O3 type with a considerable proportion of zirconium is studied. The depolarization of the ceramics is measured for shock compressions between 0 and 30 kbar. The maximum electrical energy, obtained at about 18 kbar, is of the order of 1.8 J/cm3 with Pb(Zr0.965Ti0.035)03 + 1% Nb2O5 and of the order of 0.8 J/cm3 with a Pb(Zr0.54Ti0.46)03 + 1% Nb205. As an example for application, the initiation of a 3.5 ω bridge wire PETN detonator is described.
A Simplified Oxidative Preparation of Aromatic Nitro Compounds
Authors: Gilbert E. E. , Leccacorvi J. R.
Published: December 2004

Twelve nitro‐ or chloroaromatic amines were oxidized to the nitro analogues by a simplified procedure. Limitations of the method are indicated.
Chemistry of Titanium, Zirconium and Thorium Picramates
Authors: Srivastava R. S. , Agrawal S. P. , Bhargava H. N.
Published: December 2004

Picramates of titanium, zirconium and thorium are prepared by treating the aqueous sulphate, chloride and nitrate solutions with sodium picramate. Micro‐analysis, colorimetry and spectrophoto‐ metry are used to establish the compositions (metal : ligand ratio) of these picramates as 1 : 2 (for titanium and zirconium) and 1 : 4 (for thorium). IR studies indicate H2N → Me coordination (where Me denotes the metal). A number of explosive properties of these picramates point to the fact that the zirconium picramate is thermally more stable than the picramates of titanium and thorium.
Technology of the Screw‐Extrusion Process for the manufacture of double‐base rocket propellants
Authors: Homburg A. , Brachert H.
Published: December 2004

Description of a continuous, remote‐controlled and largely automated processing method for double‐base solid propellants for the propulsion of rockets. The base materials are mixed as an aqueous batch and processed into a wet mix paste with concurrent homogenization. Kneading is a continuous and automatic process performed by disc kneaders. Compression to the granulate, as the intermediate product, is also a continuous and automatic two‐stage process performed in twin‐screw extruders with automatic mixing of the batch quantity into a homogeneous product between these two operations. Before the last operation, compression molding, the propellant mix which is continuously dewatered in the various operations, is dried to the moisture content required for the end product and, in the last stage, it is again continuously and automatically compressed in twin‐screw extruders to form the propellant grain.

This process is distinguished by the high homogeneity of the end product, high reliability, rational and material‐saving processing and a broad field of application.
Thermal Decomposition Studies on Hexahydro‐1,3,5‐trinitro‐s‐triazine (RDX) by differential scanning calorimetry
Authors: Kishore K.
Published: December 2004

Thermal decomposition of KDX has been studied by Differential Scanning Calorimetry. KDX was found to decompose significantly below its melting point. The rate and activation energy (E) of the decomposition in the open and closed‐pan conditions were different. Under closed‐pan conditions the products seem to catalyse the decomposition. The E value for the decomposition of KDX (under open‐pan conditions) both under isothermal and dynamic conditions was estimated to be (41±2) kcal/mol. The method of E estimation was free from kinetic assumptions. The order of reaction was found to be 0.6.
The High Velocity Detonation of Single Crystals of α‐Lead Azide
Authors: Chaudhri M. M. , Garrett W. L. , Sandus O. , Slagg N.
Published: December 2004

A high speed photographic study at a framing rate of 5 × 106 s−1 has been made of the propagation of high velocity detonation in single crystals of α‐lead azide. Crystals of cross section 2 mm × 2 mm and greater detonated at∼8000 m/s whereas those of smaller sizes (∼1 mm) deflagrated at ∼ 3000 m/s. Finally, the mechanism of propagation of high velocity detonation has been discussed.
Propellant Evaluations by Free Energy Minimization through Random Search
Authors: Swaminathan V.
Published: December 2004

The present paper describes a method for determining the equilibrium composition of the combustion products and the performance of propellants by using the Free Energy Minimization Technique. This minimization is sought to be carried out by a direct random search technique and systematic reduction of the size of the search region. The problem was programmed on the IBM 360/ Model 44 Computer in FORTRAN IV and rhe results for a typical metallized propellant are shown in the paper.
La Migration de la Nitroglycérine dans les Inhibiteurs de Poudres à Double‐base
Authors: Caire‐Maurisier M. , Tranchant J.
Published: December 2004

Les inhibiteurs de combustion pour blocs d'autopropulsion en propergols double‐base à la nitroglycerine sont generalement des polyesters. On montre comment et pourquoi I'ester nitrique migre de la poudre vers I'inhibiteur au cours du vieillissement, et on etudie des moyens pour eviter cette migration.
Determination of Moments of Inertia and Rotational Unbalance of a Projectile and the resulting forces on and deflections of the muzzle
Authors: Leisinger K. F.
Published: December 2004

Asymmetries in the mass distribution of a projectile lead to rotational unbalance. A technique for determining this unbalance will be described. One must distinguish between static unbalance, where the centre of gravity does not lie on the axis of rotation, and dynamic unbalance, where the axis of rotation deviates from that of one of the principal moments of inertia. On firing, due to the spin of the projectile, both kinds of unbalance lead to a bending of the barrel. This is calculated using a simple theoretical model and measured values of moments of inertia and unbalance.
EXTEST International Study Group for the standardization of the methods of testing explosives. (Formerly European commission for the standardization of the tests of explosives)
Authors: Persson P. A.
Published: December 2004

The report gives an account of the discussions and the agreements reached during the 7th meeting of the Commission together with the full texts of the 18 technical papers presented to the meeting.

Recommended standards and testing procedures were finally approved for the following:

Ballistic mortar

Transmission of detonation of ion‐exchanged explosives

Test detonators with 0.6 g and 0.25 g PETN

Method of testing the initiating strength of detonators.

The following new themes were included in the plan for the next period of work of the Commission:

Toxic fumes from explosives in blasting

Initiation and stability of detonation of slurry and water gel explosives under different conditions

Sensitivity of slurry and water gel explosives

The underwater explosion test

Deflagration and transition from deflagration to detonation.

The Commission agreed on a change of its name. The new name will be: „EXTEST International Study Group for the Standardization of the Methods of Testing Explosives”︁. A suggestion for the Commission to seek a form for association with other international corporative bodies such as the International Organization for Standardization (ISO), suitable for furthering the objectives of the Commission, was discussed and will be further investigated.

The next meeting of the Commission will be in 1978 in Czechoslovakia.
Résultats Particuliers d' Essais sur Explosifs en Gels aqueux sensibilisés à l' Aluminium
Authors: Goffart P. R.
Published: December 2004

Les slurries sensibilisés à l'aluminium, produits par simple mélange d'une solution aqueuse de sels oxydants (nitrates inorganiques) avec des combustibles à l'état sec, peuvent être amorçcables au détonateur.

Leur préparation se complète par addition d'agents de réticulation et d'allègement, qui agissent à bref délai après mélange et chargement en étui d'encartouchage ou en trou de mine: la bouillie se transforme alors en gel aqueux emprisonnant une multitude de bulles de gaz, qui sont autant de discontinuités de milieu.

On pourrait croire que ces bulles d'allègement sont indispensables pour conférer la sensibilité au détonateur, comme c'est d'ailleurs généralement le cas pour les explosifs classiques ou les slurries sensibilisés par nitrates organiques.

Nous montrons par résultats expérimentaux ayant une signification statistique, que les bulles gazeuses générées au dernier stade de la fabrication permettent certes d'ajuster la densité du gel à l'aluminium, mais que vitesse de détonation et également aptitude à détoner (au sens de sensibilité au détonateur) sont toutes deux nettement moindres lorsqu'il s'agit du gel comparé à sa bouillie‐mère d'origine, non encore réticulée ni allégée.

Cette particularité des slurries sensibilisés à l'aluminium pourrait être en rapport étroit avec leur remarquable sécurité au pompage.
Underwater Explosion
Authors: Paterson S. , Begg A. H.
Published: December 2004

The facilities and methods in use at Nobel's Explosives Company Ltd. for assessing explosive potential by the underwater method are described. Quantities measured include the velocity of detonation, the bubble period, the maximum bubble radius and the pressure‐time signature of the shock wave. From these, shock and bubble energies can be deduced and used as figures of merit for the material under test.

Results obtained in this way for a variety of types of explosive are summarized and their significance as an index of performance is discussed.
Experimental investigation into the L* instability of double base rocket propellants
Authors: Schöyer H. F. R. , De Boer R. S.
Published: December 2004

In a continuous joint research program, the Department of Aerospace Engineering of DUT and the Technological Laboratory TNO investigate unstable combustion of solid rocket propellants. Some results of this research program are discussed here. The oscillatory combustion phenomenon is discussed qualitatively, and the interaction between the acoustics of the cavity and the pyrolysis of the propellants is explained. For the investigation of the low‐frequency unstable combustion, a special device, the L* burner, is very suited. A description is given of the two L* burners of different size, which were used in the experiments discussed here. Reproducible ignition is of the utmost importance to conduct these tests. Various ignition methods have been tried and are described together with a very successful one, which was evaluated and finally selected. The experimental results of JPN and ARP propellant experiments are discussed extensively. Oscillatory combustion as well as chuffing has been observed, and it turns out that both phenomena are related to the L* and pressure. As L* burners of different sizes were used, it was possible to estimate the damping, and hence the propellant growth constant. On the basis of the results of these experiments it seems most likely that the damping is volumetric. It has been discovered that for a very large pressure range (∼ 3 MPa) the frequency of the oscillations is linearly dependent on the mean pressure, while at low pressures (<1 MPa) oscillations with a higher frequency, also dependent on the mean pressure, are observed. These observed pressurefrequency correlations are the same for the two L* burners of different size, and hence it may be concluded that these correlations are not affected by the dimensions of the motor cavity.
A New Method for Cast‐Loading Mixtures of Explosives
Authors: Witt W. , Sabranski U.
Published: December 2004

A new method for cast‐loading of explosive charges is described. Up to now cooling was used to solidify the melt of the explosive. In this method the state of the explosive is changed by applying pressure which causes an immediate rise of the melting point according to Clausius‐Clapeyron's equation. The total melt solidifies immediately and uniformly. The method has the advantage that voids are avoided and short loading times are obtained if the melting point is raised in this manner to the temperature momentarily present in the explosive.
A Design Criterion for Permissible Water Gel Explosives
Authors: Krishna Mohan V. , Srinivas M. A.
Published: December 2004

This paper presents an analysis of the relationship between oxygen balance, inert content, computed detonation parameters and incendivity for several water‐gel explosives. A mathematical technique has been developed for correlating compositional details and the permissibility test result for a number of existing compositions. The analysis covers two types of explosive compositions and three categories of permissibility tests. Using energy of detonation, oxygen balance and percentages of water and sodium chloride in the composition, this technique is able to consistently predict the permissibility test result with less than 10% exceptions. It is felt that this method will facilitate the design of new explosive formulations which have a high probability of success in permissibility tests.
Rapid Determination of Nitroguanidine and nitrate ion in the spent sulfuric acid
Authors: Chen T. H.
Published: December 2004

A rapid method for simultaneous determinations of nitroguanidine and nitrate ion in the spent sulfuric acid has been developed. This method consists of merely diluting an aliquot of sample with water and measuring the absorbances of nitroguanidine and nitrate ion at 265 nm and 203 nm, respectively. In the concentration ranges studied, average accuracies of better than 1% and 2% were obtained for nitroguanidine and nitrate ion, respectively. The precision was better than 1% in both cases.
Indirect Determination of Water in Nitroglycerin‐Nitrocellulose Pastes by gas‐liquid chromatography
Authors: Blanco J. A. , Rucci A. O. , Revuelto S. C. , Dubini A. A. , Gonzalez R. A.
Published: December 2004

A gas‐liquid chromatographic procedure was developed in connection with the determination of water in nitroglycerin‐nitrocellulose pastes. The method is based on the reaction of water with 2,2‐dimethoxypropane and its conversion to acetone which is subsequently determined. The technique is simple, rapid, and shows good accuracy and precision.

A simplified method, which is less accurate but does not involve chromatography, is also proposed.
Relation entre La Structure Electronique et la Sensibilité au Choc des Explosifs Secondaires Nitrés. III. Influence de l'environnement cristallin
Authors: Delpuech A. , Cherville J.
Published: December 2004

On étudie l'influence des interactions cristallines sur les paramètres moléculaires corrélés à la sensibilité au choc lors de précédents travaux. Les résultats obtenus permettent de mieux préciser les rǒles respectifs de la molécule et du cristal lors de l'initiation de la détonation. Ils montrent que dans ce domaine, les conclusions tirées de calculs effectués sur une molécule isolée dans sa conformation cristalline sont valables pour le cristal entier.
A model explaining the Rule for Calculating the Break‐up Time of homogeneous ductile metals
Authors: Hirsch E.
Published: December 2004

It was shown in a previous paper(1) that the break‐up time of homogenious ductile metals which elongate due to explosions, is equal to the sample's smallest initial dimension (thickness) divided by the velocity Vpl which characterizes the metal. It is attempted to explain this rule by suggesting a break‐up mechanism where holes caused by a pile‐up of vacancies are formed at the metal surface and gradually increase until breaking it. This model also predicts the existence of a strain rate threshold below which other mechanisms dominate the break‐up process. Its validity is supported by experimental evidence which is also presented.
Role of the friction coefficient in the frictional heating ignition of explosives
Authors: Andersen W. H.
Published: December 2004

An expression is developed for the friction coefficient of a material in terms of the parameters that control the friction shear. This expression in conjunction with the frictional heating equation describes the hot spot temperature produced in a friction event. Hot spot temperature increases with an increase in the particle size and shear strength of the explosive material, with an increase in the (shock) loading pressure and friction velocity, and with a decrease in material thermal conductivity. The equations are discussed in terms of their implications regarding the factors that control the sensitivity of an explosive or propellant to frictional heating under various conditions, and the results of experimental studies given in the literature.
Structure moléculaire des dérivés nitrés aromatiques. IV. Etats électroniques singulets du 1,3,5‐triamino‐2,4,6‐trinitrobenzène (TATB) dans la symétrie D3h
Authors: Leclercq J. M. , Lavenir E. , Leclercq J. , Boileau J. , Odiot S. , Blain M.
Published: December 2004

Une coupe des hypersurfaces d'énergie potentielle, le long de la coordonnée de symétrie correspondant au déplacement totalement symétrique des trois groupes NO2, est présentée pout l'état fondamental et les huit premiers états électroniques singulets excités du modèle D3h du TATB. Une suite de calculs auto‐cohérents ab initio (STO‐3 G) de l'énergie de l'état fondamental a été effectuée. Une étude semi‐empirique CNDO/S a permis d'estimer, d'une part la corrélation électronique dans cet état, d'autre part les écarts énergétiques entre les états excités singulets et le fondamental.