bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deformation behavior of plasticized poly(vinyl chloride) membranes with barium content
Authors: Abu‐Samra M. A. , Ahmad M. S. , Zihlif A. M. 
Published: May 2005

AbstractBarium complexes were embedded in plasticized poly(vinyl chloride) (PVC) membranes. Effects of these metallic complexes were followed as a function temperature and strain rate. It was found that both the elastic modulus and yield stress decrease with barium content. This behavior is attributed to a lack of uniform structure and the existence of irregularities and voids in the bulk membranes. Another factor which may reduce the tensile strength is te internal and interfacial residual stresses developed at the metal‐matrix interface. These internal stresses and the structural nonuniformity influence the electrical conduction mechanism and performance of the PVC matrix ion‐selective electrodes during aging. Also, it was observed that the yield stress of these membranes has a strain rate and temperature dependence.
Temperature measurements of polymer melts in the heating barrel during injection molding. Part 3: Effects of screw geometry
Authors: Amano Osamu , Utsugi Shirou 
Published: May 2005

AbstractWe have developed a new method to measure the true temperature of the polymer melt and its three‐dimensional distribution of a shot stored in the reservoir during injection. By means of this method, it is demonstrated that the temperature distribution of the polymer melt stored in the reservoir is strongly dependent on the setup molding conditions, the polymer investigated, and the geometry of the screw used. Further, it is noted qualitatively that there are two major effects of screw geometry on the temperature distribution of polymer melts. One, which governs strongly the temperature in the high temperature zone, is shear heat generated within the polymer itself in the metering zone of the screw during the transporting process. The second is the ability to preheat and plasticate the polymer in the compression zone, which is indispensable for uniform plastication.
Theoretical model for flow of polymer melts in the screw channel
Authors: Steller Ryszard T. 
Published: May 2005

AbstractIsothermal and nonisothermal flows of polymer melts in a screw channel are discussed. An exact solution for the isothermal flow of a power law fluid in a rectangular channel including both longitudinal and transverse velocity components is presented. A method to describe the effects of flights and curvature on flow behavior is proposed. The results are extended to deal with various nonisothermal flow conditions. The proposed theory has been numerically verified.
Design of a composite polymer plant using a simulation system
Authors: Lin Linda , Sommerfeld Jude T. , McKendry Margaret L. 
Published: May 2005

AbstractThis paper describes the use of the General Purpose Simulation System (GPSS) to simulate the manufacture of a typical line of thermotropic liquid crystal polymer resins. Specifically considered were composite polymers based on parahydroxybenzoic acid with glass, graphite, or talc added as a filler or reinforcing agent. The process examined consists of a combination of batch and semicontinuous operations. Product campaigning and equipment cleaning requirements were also incorporated into the GPSS model. Different equipment configurations and manpower distributions were simulated to aid in the design of such a polymer plant. The simulation results were analyzed, and the calculated return on investment was used to select the final plant design.
On the synthesis of poly(ε‐caprolactam)—poly(butadiene‐co‐acrylonitrile) block copolymers for the reaction injection molding process
Authors: Stehlíček Jaroslav , Lednický Frantiček , Baldrian Josef , Šebenda Jan , Neuhäusl Emil 
Published: May 2005

AbstractThe liquid rubbers Hycar ATBN and HTBN were used in the preparation of poly(ε‐caprolactam)—poly(butadiene‐co‐acrylonitrile) block copolymers intended for reaction injection molding by the anionic polymerization of ε‐caprolactam. The conversion of Hycar end groups to polymerization growth centers and the conditions of polymerization influence the crystallization, morphology, and mechanical properties of the product through its molecular structure. The contribution of individual reactions to this molecular structure is discussed.
Laser interferometry: A measurement technique for diffusion studies in thin polymer films
Authors: Saenger K. L. , Tong H. M. 
Published: May 2005

AbstractLaser interferometric techniques have many applications in the area of thin film science and technology due to their sensitivity, simplicity, and low cost. Typically, changes in thickness and/or refractive index of a transparent polymer film sample are detected from changes in film reflectivity, as measured by variations in the intensity of reflected laser light. Diffusion related properties such as solvent uptake/swelling, dissolution, and drying rates are accessible with laser interferometry since each of these processes involves a change in the film's thickness and/or refractive index. The principles and basic experimental considerations common to these three applications will be discussed. Illustrative examples from our lab will include n‐methyl‐2‐pyrrolidone diffusion in polyimide, and methanol diffusion in poly(methyl methacrylate).
Dynamic melt rheology. I: Re‐examining dynamic viscosity in relationship to the steady shear flow viscosity
Authors: Khanna Y. P. 
Published: May 2005

AbstractSince 1950's, theoretical as well as experimental efforts have been made to explain the similarity between the shear rate dependence of the steady flow apparent viscosity and the frequency dependence of the dynamic viscosity. The literature points out agreements, as well as occasional disagreements, between the two viscosity terms, depending on the polymer system. In this manuscript, some critical results are presented which suggest that the strain rate dependence of the two viscosities, has entirely different origins and that it is only a coincidence that these data happen to be closer for the common polymers. A time‐temperature dependence of viscoelastic parameters is brought into the discussion to argue the observed pseudo‐plasticity in dynamic melt rheology and to demonstrate, in principle, that the strain rate dependence of the dynamic and steady flow viscosities should be different. Nevertheless, we must mention that the dynamic and steady flow measurements have their own merits and these techniques can complement each other very well.
Electrically conductive adhesives: Effect of particle composition and size distribution
Authors: Lyons Alan M. 
Published: May 2005

AbstractThe effects of particle composition and size distribution on the electrical properties of conductive adhesives were studied. Silver‐plated glass and silver‐plated nickel particles with both narrow (37‐44 μm) and broad (< 44 μm) size distributions were dispersed in an epoxy matrix. In all cases, formulations incorporating narrow particle size distributions required greater concentrations of particles to exceed the percolation threshold for electrical conduction than when broad particle distributions were used. Differences between glass and nickel particles were observed and attributed to the higher density of nickel particles, as well as subtle variations in particle size distributions.
Structure development during flow of polyblends containing liquid crystalline polymers
Authors: Beery D. , Kenig S. , Siegmann A. 
Published: May 2005

AbstractThe microstructure development during capillary flow of polyblends containing Liquid Crystalline Polymers (LCPs) was studied. In the present investigation the wholly aromatic LCP constituent was the minor phase suspended in polycarbonate (PC), poly(butyleneterephthalate) (PBT) or Nylon 6 (N‐6), in addition to previously studied amorphous nylon matrix Experimental results showed that the viscous forces acting at the components' interface are predominating the elongational deformation and the resulting structure development of the LCP phase. In cases where the viscosity of the suspending matrix was higher than the LCP one (PC, amorphous nylon) scanning electron micrographs indicated that fibrillar structure developed. In cases where the viscosity of the matrix polymers was lower than the LCP suspended phase, fibrous structures developed only at very high shear rates. Due to velocity rearrangement effects at the capillary exit a skin core morphology was observed. Since the polymers viscosity depends both on shear rate and temperature, the in situ composite structure development depends on the specific processing methods and conditions that the LCP containing polyblends experience.
Methods of describing oxidation reactions in fractal spaces
Authors: Kozlov GV , Afaunova ZI , Zaikov GE 
Published: May 2005

AbstractThree methods for describing kinetic curves of oxygen consumption using the scaling approach and fractal analysis are offered. These models are used for the description of the polymer melt structure. All three methods account for the nonuniformity of this structure, which is characteristic for a fractal object, and give the correct description of kinetic curves of the autodecelerated type. Copyright © 2005 Society of Chemical Industry
Chemical and Morphological Characterization of Ultra‐Thin Fluorocarbon Plasma‐Polymer Deposition on 316 Stainless Steel Substrates: A First Step Toward the Improvement of the Long‐Term Safety of Coated‐Stents
Authors: Haïdopoulos Marie , Turgeon Stéphane , Laroche Gaétan , Mantovani Diego 
Published: May 2005

AbstractSummary: Metallic intravascular stents are medical devices used to scaffold a biological lumen, most often diseased arteries, after balloon angioplasty. They are commonly made of 316L stainless steel or Nitinol, two alloys containing nickel and chromium, which are classified as potentially toxic and carcinogenic by the International Agency for Research on Cancer. Their long‐term safety is therefore controversial, since the corrosion processes may lead to the release of several metallic compounds potentially toxic. Therefore, the strategy behind this work was to develop a process aiming the complete isolation of the devices from the body fluids by a thin, cohesive and strongly adherent coating of a plasma‐polymerized fluoropolymer. Ultra thin fluorocarbon films were deposited on pre‐treated stainless steel surfaces by radio frequency glow discharge plasma. Chemical composition, structure, hydrophobicity and morphology of the plasma‐polymer films were investigated by X‐ray photoelectron spectroscopy, Fourier‐transform infrared spectroscopy, water contact angle measurements and atomic force microscopy. Results show that the films were partially hydrogenated, amorphous, highly hydrophobic, smooth and pinhole‐free. Deposition on as‐received substrates however leads to partially hydrogenated, porous fluorocarbon coatings that consisted of heterogeneously distributed nanospherical particles. Thus, careful pre‐treatment prior to deposition proved essential, as demonstrated by its strong influence on the chemical composition of the interface, as well as the chemical structure and the morphology of the plasma‐polymer films. Finally, plasma‐polymer films were validated with respect to impermeability in a medium reproducing the physiological conditions that prevail in coronary arteries.
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Nanoporous Organosilicate Glass Films via Chemical Vapor Deposition onto Colloidal Crystal Templates
Authors: Wu Qingguo , Ross April D. , Gleason Karen K. 
Published: May 2005

AbstractSummary: Templated nanoporous organosilicate glass (OSG) films with extremely low dielectric constants and refractive indeces, as low as 1.4 and 1.067 respectively, were fabricated via chemical vapor deposition. Well‐ordered assemblies of polymer nanospheres serve as templates for the pores. To enable three‐dimensional crystal templates to form on substrate areas larger than 10 cm2, a method using rapid evaporation‐induced self‐assembly of polystyrene (PS) nanospheres was developed. Conformal plasma‐enhanced CVD using dimethylsilane and oxygen precursors fills the interstices of the colloidal crystal to form the OSG matrix. With subsequent annealing at 500 °C the labile polymer beads decompose, resulting in a nanoporous organosilicate thin film.TEM image of nanoporous OSG film using the 15 nm bead template.magnified imageTEM image of nanoporous OSG film using the 15 nm bead template.
Particle Characterization, Present State and possible Future Trends
Authors: Leschonski Kurt 
Published: May 2005

AbstractThe investigations of single and combined properties of particles or of particulate matter still belongs to the most important areas of present research and practical applications of Particle Characterization. Methods to measure single particle properties, as for instance particle size, shape, composition and velocity, are of much higher sophistication than before and they still aim at improved accuracy and higher resolution. There still is a considerable lack of understanding, and lack of theoretical interpretation and of experimental evidence of the differences seen in the correlation of different equivalent diameters, obtained when analysing the same irregularly shaped particle, or a distribution of particles, using different physical principles. Furthermore, there still is a lack of understanding of the influence of shape on the results obtained with optical methods using diffraction, light scattering etc., thus asking for more information with respect to the transferability of results from one physical principle to another. The measurement of combined particle properties comprises the simultaneous measurement of, for instance, size, velocity and concentration, which is of particular importance in the comprehensive description of multiphase flow systems. Those instruments which are in working order are highly complicated, not easy to use and to handle and they are in most cases special adaptations for a limited range of the variables to be analysed. There is also growing interest in the evaluation of socalled property functions. Particle Characterization will remain for quite a number of years just as exciting as it has been in the past. If industrial demand enforces the use of on‐line instrumentation it might even become more interesting.
Applications of Condition Numbers A‐priori Analysis of Moment Method for Describing Size Distributions
Authors: Gentry James W. , Calabrese Richard V. 
Published: May 2005

AbstractA procedure for estimating the effectiveness of algorithms which retrieve size distribution parameters from cumulative fractions or moments is described. The principle of the algorithm is to select moments, or cumulative fractions, which minimize the condition number. Extensive tests of the algorithm for a distribution consisting of the sum of two log normal distributions were carried out. This procedure can be easily extended to use different numbers and types of constituent functions. The simulations indicated that moment methods which include positive and negative moments give the best result. When the means of the constituent distribution are close, the large condition numbers indicate that no algorithm will give unambiguous values for the parameters.
Triboelectric Charging of Polymer Particles by Impact
Authors: Yamamoto Hideo , Scarlett Brian 
Published: May 2005

AbstractThis paper describes an experimental investigation of the charge acquired by a single polymer particle when striking a plate. The particle was projected from a pneumatic gun with variable velocity and angle of impact. The deflected particle was then captured in a Faraday cup and the net acquired charge so measured. The measurements of charge are related, particularly, to the initial potential of the surfaces and to their work functions.
Estimation of Particle Size Distributions Using Pipet‐Withdrawal Centrifuges
Authors: Dumm Timothy F. , Hogg Richard 
Published: May 2005

AbstractThe mathematical treatments used in the evaluation of particle size distribution from pipet‐withdrawal centrifuge data are reviewed. An error in the published procedure for multiple‐sample withdrawal systems is pointed out and a corrected formulation is presented. An alternative treatment, based on a piece‐wise linearization of the size distribution is described. Computer simulations of the analytical and data evaluation procedures indicate that the errors in the original formulation are not generally serious and that the corrected and alternative procedures lead to very similar estimates. Except for some cases involving very narrow size distributions, the alternative approach appears to give slightly closer estimates of the size distribution. Comparisons based on actual experimental data are also described.
Observations during Reactions and Melting of Freely Suspended Solid Particles
Authors: Straubel Harald , Straubel Edith 
Published: May 2005

AbstractWith the three‐plate‐capacitor method, as described previously by the author, reactions and heating processes in freely suspended particles (diameter 5‐50 μm) were investigated by using the diffraction pattern of a laser beam. Change of weight can be registered, during operation, by the a. c. and d. c. voltage connected to a capacitor. This device enables information to be obtained, from inside the droplets, on the gradient of density or the precipitation of small particles and on the formation and solution process of a crystal nucleus in anorganic and low molecular organic substances. The behaviour of high polymer materials was studied during heating in the central region ca. 4 μm of the droplet.The diffraction patterns are similar to those of crystals (micells), but they do not show any crystal nucleus in the center. The application of heat, up to the softening point, gradually diffuses this cell arrangement. Such phenomena have not previously been studied within a droplet.
Explosive desensitization studies via chemical group modification. Nitroso‐Derivatives of RDX and 3‐Amino‐TNT
Authors: Iyer S. 
Published: May 2005

AbstractWith aims toward desensitizing RDX and TNT via molecular modification, mono‐ and trinitroso‐derivatives of RDX and 3‐amino‐TNT were synthesized and subjected to sensitivity tests. Impact and shock sensitivity data show these compounds to be markedly desensitized. Explosive yield measurements indicate that the changes in power output due to these molecular modifications are minor.
A contribution to the Study of Decomposition and Combustion of HMX. influence of some additives
Authors: Cohen‐Nir E. , Sannier H. 
Published: May 2005

AbstractThe work presented is an initial step in the attempt to obtain higher burning rates with nitramine‐based propellants. We have studied the influence of some boron and sodium compounds on the decomposition mechanism and on the burning rate of HMX. Results indicate that additives such as hydrazine monoborane, sodium boron hydride and methylamine monoborane lead to a significant increase of the decomposition heat of HMX and reduce as well as the activation energy and the temperature of maximum decomposition rate.Experimental results about rb(p) and rb(To) laws of HMX and HMX/additive mixtures are presented. Quantitative investigations show that the burning rate of HMX can be increased by approximately a factor of 3 by addition of 10% boron compounds. Moreover, the pressure exponent is reduced from 0.9 to 0.6.
Some physicochemical problems of extraction of explosives from ammunition
Authors: Kondrikov Boris N. 
Published: May 2005

AbstractHeat exchange peculiarities, burning heat instability phenomena, and the possible ways of initiation of a charge of explosive at dismantlement of ammunition are considered as the physico chemical ground for elaboration of the dismantlement methods of the higher productivity and safety. Melting of the explosive, contact and non‐contact mechanical technologies, unscrewing, cutting, milling, and turning of the ammunition are studied in outline from the point of view of the considered physicochemical processes importance, and some proposals concerning augmentation of safety and productivity of the dismantlement methods are formulated.
Modelling of the Shaped Charge Jet Break‐Up
Authors: Hennequin E. 
Published: May 2005

AbstractA new model for shaped charge jet break‐up was devised. For this purpose, the fragments of a shaped charge jet were analyzed and their characteristics compared against the ones predicted by the break‐up proposed by Pfeffer, Hirsch, Chou und Haugstad. As the predictions provided by these models are not fully satisfactory, the break‐up process was analyzed in order to develop a new break‐up model which provides a better estimation of the break‐up time and the accumulated length of the jet. This model makes use of one parameter, the fragment shape index, which can be determined ex‐ perimentally. This parameter characterizes the type of jet break‐up (ductile or brittle) and is hence indicative of the jet quality.
Rheology of HTPB Propellant: Development of generalized correlation and evaluation of pot life
Authors: Muthiah Rm. , Krishnamurthy V. N. , Gupta B. R. 
Published: May 2005

AbstractComposite solid propellants based on hydroxy‐terminated polybutadiene (HTPB) have become the workhorse propellants in the present‐day solid rocket motors world‐wide. Because of the high solid loading, the rheological behavior of such propellants is quite complex. The effect of solid loading, oxidizer particle size and aluminium content has been studied and reported. Similarly, the effect of temperature and mixer kinematics and mixing cycle time have also been studied and reported. In the present paper a generalized correlation has been developed for shear stress‐shear rate based on the rheological parameters like yield stress, consistency index and pseudoplasticity index which are in turn functions of solid volume fraction, cure time, t, and temperature, and has a correlation coefficient of 0.94 with the experimental values. Also a commonly used term in propellant industries, pot life, has been defined and evaluated for the HTPB propellant system.
Estimation of Aluminium in HTPB Based Composite Solid Propellants by hydrogen evolution method
Authors: Ajaz Aslam G. 
Published: May 2005

AbstractHydrogen gas evolution method has been applied to determine the percentage of aluminium (Al) in hydroxy‐terminated polybutadiene (HTPB) based composite solid propellants premix/pastes. The determination is not effected by the presence of Zn, Fe, Cu or small amounts of silicon but magnesium has been found to interfere in the analysis. The results are obtained with remarkable accuracy and reproducibility.
Thermoanalytical Investigations on the Effect of Atmospheric Oxygen on HTPB resin
Authors: Ninan K. N. , Krishnan K. , Rajeev R. , Viswanathan G. 
Published: May 2005

AbstractTG‐DSC studies, carried out on hydroxy‐terminated polybutadiene (HTPB) in air and nitrogen atmospheres show three transitions which give rise to (1) an exothermic DSC peak and mass gain in TG at 170°C–240°C, seen only in air (2) exothermic peak and low mass loss, both in air and nitrogen, due to depolymerization, cyclization and cross linking, and (3) final mass loss corresponding to pyrolysis in nitrogen and combustion in air, appearing respectively as an endothermic peak and as a sharp exothermic peak in the two atmospheres. The FTIR spectrum of the product isolated from TG after the mass gain step shows addition of oxygen to the butadiene back bone. Arrhenius activation parameters (E and A) were computed for the exothermic oxygen addition reaction. The Ozawa method refined by MKN two‐term approximation for p(x) function gave results quite comparable to those from Kissinger method.