bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of density distributions in injection molded amorphous engineering plastics. Part II
Authors: Yu Jeong S. , Kalyon Dilhan M. 
Published: December 2004

AbstractThe experimental results obtained on the gapwise density distributions of freely quenched and injection molded specimens of two engineering thermoplastics presented in Part I of this paper were compared with simulation results. The effect of the thermal history on the density development in the freely quenched samples was investigated by employing the fictive temperature concept in conjunction with the experimentally determined material characteristics. The density distribution in freely quenched specimens of poly(ether imide) could be readily predicted. The combined effects of the cooling rate and the pressure history on the density distributions of injection molded samples were also investigated. A phenomenological model was developed to combine the effects of thermal and pressure history on the density distribution. Overall, the predicted results for injection molded specimens agreed well with the experimental results.
Effect of melt spinning and cold drawing on structure and properties of poly (aryl ether ketone) (PAEK) fibers
Authors: Hsiung C. M. , Cakmak M. 
Published: December 2004

AbstractThe effects of melt spinning and cold drawing on structure development and resulting properties of poly (aryl ether ketone) (PAEK) have been investigated. Melt spun and subsequently cold drawn fibers were characterized by differential scanning calorimetry, wide angle X‐ray diffraction, small angle X‐ray diffraction, and birefringence techniques. At low take‐up speeds, essentially amorphous fibers are produced. High take‐up speeds result in development of crystallinity in the as‐spun fibers. Cold drawing above the, Tg of PAEK causes further increase of crystallinity. Wide angle X‐ray patterns indicate progressive alignment of chains along the fiber axis in as spun as well as in cold‐drawn fibers with the draw down ratio and cold draw ratio. However, cold drawing was observed to broaden the WAXS peaks. SAXS patterns of cold drawn and fixed annealed fibers changed from two‐point to four‐point patterns indicating mosaic pattern formation of crystalline and amorphous regions. Mechanical properties including tensile strength, elongation at break, modulus, and yield strength were measured and correlated with fiber structure. Fracture surfaces of tensile tested fibers were observed using scanning electron microscopy and correlated with developed fiber structure.
Molecular and lamellar structure of an extrusion‐grade medium‐density polyethylene for gas distribution
Authors: Tränkner T. , Hedenqvist M. , Gedde U. W. 
Published: December 2004

AbstractAn extrusion‐grade medium‐density polyethylene was fractionated by size exclusion chromatography and selective solvent extraction. The fractions were studied by infrared spectroscopy, differential scanning calorimetry, and transmission electron microscopy. Infrared spectroscopy showed that chain branching was concentrated to the low molar mass material. Transmission electron microscopy showed the presence of roof‐shaped crystals in the low molar mass samples and curved S‐or C‐shaped lamellae in the high molar mass samples. These features could be used for identification of different molar mass species in the unfractionated sample.
Rubber modified epoxy resin. II: Phase separation behavior
Authors: Kim Dae Su , Kim Sung Chul 
Published: December 2004

AbstractDGEBA (diglycidyl ether of bisphenol A)–ATBN (amine terminated butadiene acrylonitrile copolymer) blends exhibited upper critical solution temperature (UCST) behavior. Triethylene tetramine (TETA) was introduced as an amine curing agent of epoxy. The real‐time phase separation behavior of ATBN‐added epoxy system during cure was investigated using laser light scattering. SEM (scanning electron microscopy) and optical microscopy were also employed to observe the morphology of the epoxy blends. Since the DGEBA–ATBN blends showed UCST behavior, the degree of phase separation when cured at low temperature was higher than that when cured at high temperature. The domain correlation length increased as the curing temperature was lowered. Dynamic mechanical analysis (DMA) results indicated that the phase inversion occurred above 20 wt% of ATBN composition.
Rheology and physical properties of ternary blends containing a thermotropic liquid crystalline copolyester
Authors: Hong Soon Man , Kim Byoung Chul 
Published: December 2004

AbstractTernary blends of polyarylate (PAR) U‐Polymer 100, thermotropic liquid crystalline copolyester (LCP) Vectra A950, and a block copolyesterether Hytrel 7246 were investigated in terms of rheological properties, morphology, and mechanical properties. The PAR/Hytrel blend exhibited melting point depression and gave a unique single Tg over the entire range of blend compositions. Addition of Hytrel to the PAR/LCP blend decreased both dynamic viscosity and storage modulus over the normal processing temperature range. Further, it notably reduced the voids between the LCP domains and the matrix, and improved the mechanical properties. The optimum usage level of Hytrel proved to be 2 phr.
Analytical approximation of degradation profiles in polymer products
Authors: Jansen K. M. B. 
Published: December 2004

AbstractA general, but simple, analytical technique is proposed for the solution of diffusion‐controlled reaction problems (as, for example, occur during the photooxidation of polymers). With this technique the stationary concentration and reaction rate profiles can be calculated for arbitrary reaction kinetics and concentration dependent diffusion coefficients. As an example, the photo‐oxidation of polyolefins is considered, which involves complex, concentration dependent, reaction kinetics. Excellent agreement between the analytical approximation and the numerical solution is obtained. Further, an analytical expression for the degradation profile (extend of reaction) is derived, which includes the starting‐up effect. It is shown that owing to instationary effects, the degradation profiles obtained with artificial weathering tests may differ considerably from those obtained with outdoor weathering experiments. It is therefore suggested that artificial weathering tests be used to measure the reaction rate parameter and calculate the degradation profile rather than measuring the degradation profile directly.
Synthesis and characterization of polyamides and poly(amide‐imide)s derived from 2,6‐bis(3‐aminophenoxy)benzonitrile or 2,6‐bis(4‐aminophenoxy)benzonitrile
Authors: Saxena Akanksha , Prabhakaran PV , Rao V Lakshmana , Ninan KN 
Published: December 2004

AbstractA series of polyamides and poly(amide‐imide)s was prepared by direct polycondensation of ether and nitrile group containing aromatic diamines with aromatic dicarboxylic acids and bis(carboxyphthalimide)s respectively in N‐methyl 2‐pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. New diamines, such as 2,6‐bis(4‐aminophenoxy)benzonitrile and 2,6‐bis(3‐aminophenoxy)benzonitrile, were prepared from 2,6‐dichlorobenzonitrile with 4‐aminophenol and 3‐aminophenol, respectively, in NMP using potassium carbonate. Bis(carboxyphthalimide)s were prepared from the reaction of trimellitic anhydride with various aromatic diamines in N,N′‐dimethyl formamide. The inherent viscosities of the resulting polymers were in the range of 0.27 to 0.93 dl g−1 in NMP and the glass transition temperatures were between 175 and 298 °C. All polymers were soluble in dipolar aprotic solvents such as dimethylsulfoxide, dimethylacetamide and NMP. All polymers were stable up to 350 °C with a char yield of above 40 % at 900 °C in nitrogen atmosphere. All polymers were found to be amorphous except the polyamide derived from isophthalic acid and the poly(amide‐imide)s derived from diaminodiphenylether and diaminobenzophenone based bis(carboxyphthalimide)s. Copyright © 2004 Society of Chemical Industry
Curing behaviour of syndiotactic polystyrene–epoxy blends: 1. Kinetics of curing and phase separation process
Authors: Salmon Nicolas , Carlier Véronique , Schut Jaap , Remiro Pedro M , Mondragon Ińaki 
Published: December 2004

AbstractThe modification of the curing behaviour and the phase separation process for an epoxy resin blended with a crystalline thermoplastic was investigated in the case of the diglycidylether of bisphenol‐A (DGEBA)/4,4′‐methylene bis(3‐chloro‐2,6‐diethylaniline) (MCDEA) blended with syndiotactic polystyrene (sPS) and cured at 220 °C. Phase separation taking place during curing of the blend was investigated by differential scanning calorimetry (DSC) and optical microscopy in order to get a better understanding of the complex interactions between cure kinetics of epoxy matrix and crystallisation of sPS, both influenced by blend composition. Results suggested that phase separation and crystallisation of sPS occurred at almost similar times, with phase separation just being ahead of crystallisation. DSC and near‐infrared measurements were used for the determination of the cure kinetics. Slow delays on the cure reactions were observed during the first minutes for the sPS‐containing blends compared with the neat DGEBA/MCDEA system but, after some time, the reaction rate became faster for the blends than for the neat matrix. Phase separation occurring in the mixtures may explain this particular phenomenon. Copyright © 2004 Society of Chemical Industry
Influence of the ethylene–(methacrylic acid)–Zn2+ ionomer on the thermal and mechanical properties of blends of poly(propylene) (PP)/ethylene–(vinyl alcohol) copolymer (EVOH)
Authors: Abad Maria J , Ares Ana , Barral Luis , Eguiazábal Jose I 
Published: December 2004

AbstractThe thermal and mechanical properties and the morphologies of blends of poly(propylene) (PP) and an ethylene–(vinyl alcohol) copolymer (EVOH) and of blends of PP/EVOH/ethylene–(methacrylic acid)–Zn2+ ionomer were studied to establish the influence of the ionomer addition on the compatibilization of PP/EVOH blends and on their properties. The oxygen transmission rate (O2TR) values of the blends were measured as well. PP and EVOH are initially incompatible as was determined by tensile tests and scanning electronic microscopy. Addition of the ionomer Zn2+ led to good compatibility and mechanical behaviour was improved in all blends. The mechanical properties on extruded films were studied for 90/10 and 80/20 w/w PP/EVOH blends compatibilized with 10 % of ionomer Zn2+. These experiments have shown that the tensile properties are better than in the injection‐moulded samples. The stretching during the extrusion improved the compatibility of the blends, diminishing the size of EVOH domains and enhancing their distribution in the PP matrix. As was to be expected, the EVOH improved the oxygen permeation of the films, even in compatibilized blends. Copyright © 2004 Society of Chemical Industry
Synthesis and characterization of UV‐curable acrylic resin containing fluorine groups
Authors: Park Soo‐Jin , Jin Fan‐Long 
Published: December 2004

AbstractA novel fluorine‐containing acrylic resin, 4‐trifluoromethylphenyl glycerol dimethacrylate (TPGD), was synthesized and the structure was characterized by FTIR, 13C NMR, 1H NMR, and 19F NMR spectroscopy. The conversion of cure reaction, thermal stability, glass transition temperature (Tg), and electrical properties of the TPGD acrylic resin cured with UV radiation were investigated. The thermal stability and Tg of the UV‐cured specimens show a maximum value at 1 wt% photoinitiator, due to the formation of advanced network structures. The cured specimens had a relatively low dielectric constant, attributed to the decreased deformation polarizability of segment motion in the fluorine‐containing resin. Copyright © 2004 Society of Chemical Industry
The Technology of Droplet Measurement with Cascade Impactors
Authors: Büurkholz Armin 
Published: December 2004

AbstractCascade impactors are still the most suitable devices with which to measure fine droplet mists in gas ducts. This report describes the measurement technique and underlying principles. It is based largely on experience gained with a type of impactor that has been specially developed for droplet measurements, and also on applications of impactors in the chemical industry. Most of the measurement work has been undertaken in connection with environmental protection. The cascade impactor gives the mass‐related droplet size distributions and concentrations within a range extending from about 0.2 to 10 microns. Larger droplets are collected quantitatively in the sampling probe, which serves as a precollector.
Drop‐Size Distributions Produced by Flat‐Spray Nozzles
Authors: Schegk Claus‐Detlef , Lüoffler Friedrich , Umhauer Heinz 
Published: December 2004

AbstractThis study deals with measurements of the drop‐size distributions of different types of fan spray atomisers using a scattered‐light particle size counting analyser. The drop‐size distributions were determined at various locations in the spray cone. These local distributions change systematically from the fan's axis to its border. Superimposing these local distributions, adequately weighted, one acquires the entire distribution of all the drops. A comparison of the experimental results is made with those yielded by mathematical equations.
Studies of shaped charges with built‐in asymmetries. Part II: Modelling
Authors: Brown John , Edwards P. J. , Lee P. R. 
Published: December 2004

AbstractA well‐characterized shaped charge was used to study the influence of asymmetrical initiation on the jet. An experimental study yielded flash radiographs of the jets from charges fired with the initiation point offset 2, 4, 6, 8 and 10 mm, respectively, from the central axis. The axial and lateral velocities of the jet particles were determined from the sets of radiographs. In a previous paper it was hypothesized that a simple relationship might exist between the departure vectors of the jet particles and the geometry of the impingement of the detonation front on the liner. Any part of the jet from an asymmetrically initiated shaped charge departs at an angle determined by the difference between the current angle between the actual detonation wave where it contacts the liner, and that which would have arisen had the initiation been perfectly axial. We set up a simple computer code which evaluates, for any given initiation offset distance, the instantaneous angles between the detonation front and the successive elements of the liner which are encountered as the wave sweeps along it. Since it is possible to map particle velocities in the jet on to those regions of the liner where they originated, simulated sets of axial and lateral jet velocities were readily generated. Agreement between theory and experiment is sufficiently close to suggest that our approximation is useful and can assist in understanding the jet dynamics of asymmetrically initiated shaped charges.
On application of the plate dent test for the performance evaluation of emulsion explosives
Authors: Ravi Shankar G. S. R. , Kumar A. S. , Krishna Mohan V. 
Published: December 2004

AbstractThe use of plate dent technique to evaluate w/o emulsion explosives is discussed in this paper. Experiments carried out with aluminium and mildsteel blocks show that the dent test results could give an idea about explosive performance. Attempts have been made to correlate the plate dent data with various detonation properties. Estimated detonation pressure did not yield a satisfactory correlation with either dent depth or dent volume. The role of detonation energy in governing the test result is highlighted. It is suggested that the plate dent test could be employed to assess the performance characteristics of large diameter, booster sensitive explosives.
Characteristic Properties of AN/GAP‐Propellants
Authors: Menke Klaus , Böhnlein‐Mauß Jutta , Schubert Hiltmar 
Published: December 2004

AbstractFormulations based on ammonium nitrate and GAP are promising candidates for the development of high energetic, minimum smoke propellants with reduced sensitivity to be applied for radar and laser guided tactical missiles. The difficulties for the development of such a propellant system depend on the chemical nature and problems connected to the ingredients. Drawbacks are caused by the numerous phase changes of AN, its hygroscopicity, lower energy and low reactivity. The key problems for the development are the unfavourable combustion behaviour and sometimes bad stability of AN/GAP formulations.Some of the main features of these propellants have been developed and illustrated in this paper. These are performance, chemical stability, combustion behaviour and detonation sensitivity. Four different kinds of pure and phase stabilized ammonium nitrates are compared regarding stability and combustion behaviour in propellant formulations with GAP and nitrate ester plasticizers. Satisfying solutions have been found for combustion behaviour and stability of AN/GAP‐propellants, if pure AN, atomized from the melt and new molybdenum oxide/vanadium oxide burning modifiers are successfully applied.
Explosive Systems Utilizing Semiconductor Bridge, SCB, Technology
Authors: Bickes R. W. 
Published: December 2004

AbstractSandia National Laboratories' semiconductor bridge, SCB, is a maturing technology now in use in several new applications. Those applications required explosive assemblies that were light weight, small volume, low cost, and needed only small quantities of electrical energy to function. Explosive assembly here refers to the combination of the firing set (the current source for the firing signal) and the explosive component. Because conventional firing systems could not meet the new reduced size, weight and energy requirements, SCB systems were developed for applications that range from Sandia devices to commercial igniters for fireworks. This paper is a brief overview of SCB technology with examples of SCB explosive systems designed to meet modern requirements.
Electric Detonators: EBW and EFI
Authors: Varesh Ron 
Published: December 2004

AbstractExploding Bridge Wire Detonators (EBW) and Exploding Foil Initiators (EFI) which were originally developed for military applications, have found numerous uses in the non‐military commercial market while still retaining their military use. While not as common as the more familiar hot wire initiators, EBW's and EFI's have definite advantages in certain applications. These advantages, and disadvantages, are discussed for typical designs.
Application of Fractal Geometry to Dynamical Impacting of condensed explosives and other materials
Authors: Guanren Zhang 
Published: December 2004

AbstractThe relation between fractal dimension D of impacting condensed explosive sample and its related physical parameters is derived. With this relation, and the frame photograph of impacting, the threshold energy required to initiate any physical or chemical process, such as melting, ignition or detonation can be calculated.
Prompt Shock Initiation of Cased Explosives by Projectile Impact
Authors: James H. R. , Haskins P. J. , Cook M. D. 
Published: December 2004

AbstractExperimental results often show that a prompt shock response to projectile impact can be experienced by even relatively heavily cased explosives. This paper will discuss the predictive criteria that can be applied in such circumstances, and in particular will explore the different mechanisms which are present for rod and sphere impacts. Predicted initiation thresholds are shown to give good comparisons with experimental results, using, at most, two empirical shock sensitivity constants obtained from impacts of the uncased explosive.
Stabilizer Reaction is Cast Double Base Rocket Propellants. Part VIII: Characterization of propellant gassing properties during simulated aging
Authors: Sammour M. H. 
Published: December 2004

AbstractThe decomposition process of two cast double base (CDB) propellant compositions was measured in vacuum. The process of gas evolution during heating of propellant compositions in vacuum has been studied using Vacuum Stability Test (VST) and Gas chromatography/ Mass Spectrometry (GC‐MS) techniques. The results for the two different compositions aged at different storage temperatures for different periods of time were compared.VST has been used to quantify the amount of gases evolved during heating of propellant (aged and unaged) compositions at 100°C in vacuum, while quantitative GC‐MS has been used to identify and quantify the evolved gases when the same propellant compositions were heated at 60 °C and 70 °C at low free volume.The results have shown that the amount and type of gases evolved depend on the composition of propellant, percentage of stabilizer etc. Composition 1 evolved CO2, CO, N2, NO and N2O and produced the greater total gas volume, while Composition 2 evolved C02, CO and N2 only. In each case C02 was the predominant gas and Composition 1 produced more COz but less CO than Composition 2. It is suggested that these differences in gas evolution profiles are due to the presence of different ballistic modifiers in the two propellant compositions.Gas evolution assessment using VST technique cannot be the strict measure of double base propellants stability.
Imidazolinone‐tolerant crops: history, current status and future
Authors: Tan Siyuan , Evans Richard R , Dahmer Mark L , Singh Bijay K , Shaner Dale L 
Published: December 2004

AbstractImidazolinone herbicides, which include imazapyr, imazapic, imazethapyr, imazamox, imazamethabenz and imazaquin, control weeds by inhibiting the enzyme acetohydroxyacid synthase (AHAS), also called acetolactate synthase (ALS). AHAS is a critical enzyme for the biosynthesis of branched‐chain amino acids in plants. Several variant AHAS genes conferring imidazolinone tolerance were discovered in plants through mutagenesis and selection, and were used to create imidazolinone‐tolerant maize (Zea mays L), wheat (Triticum aestivum L), rice (Oryza sativa L), oilseed rape (Brassica napus L) and sunflower (Helianthus annuus L). These crops were developed using conventional breeding methods and commercialized as Clearfield* crops from 1992 to the present. Imidazolinone herbicides control a broad spectrum of grass and broadleaf weeds in imidazolinone‐tolerant crops, including weeds that are closely related to the crop itself and some key parasitic weeds. Imidazolinone‐tolerant crops may also prevent rotational crop injury and injury caused by interaction between AHAS‐inhibiting herbicides and insecticides. A single target‐site mutation in the AHAS gene may confer tolerance to AHAS‐inhibiting herbicides, so that it is technically possible to develop the imidazolinone‐tolerance trait in many crops. Activities are currently directed toward the continued improvement of imidazolinone tolerance and development of new Clearfield* crops. Management of herbicide‐resistant weeds and gene flow from crops to weeds are issues that must be considered with the development of any herbicide‐resistant crop. Thus extensive stewardship programs have been developed to address these issues for Clearfield* crops. Copyright © 2005 Society of Chemical Industry