bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chirulen® — ein Halbzeug aus ultrahochmolekularem Polyäthylen für Implantate
Authors: Berzen J. , Braun G. , Spengler H. 
Published: December 2004

AbstractEs wird eine zusammenfassende Darstellung über die Entwicklung der Gelenkplastik – insbesondere unter Berücksichtigung von Chirulen®– gegeben. Bei diesem Material handelt es sich um ein Halbzeug aus ultrahochmolekularem Polyäthylen mit sehr hohem Reinheitsgrad, das nach dem Ziegler‐Verfahren hergestellt wird. Es hat sich nach biologischen Prüfungen und klinischen Befunden wegen seiner günstigen physikalischen Eigenschaften als Prothesenmaterial gut bewährt. Seine besonderen Vorzüge sind, daß es
während des physiologischen Gangablaufes, bei dem am Schenkelkopf eine Druckkraft von etwa dem 5fachen Körpergewicht auftritt, hervorragende Gleit‐ und Verschleißeigenschaften zeigt, und
bei der Sterilisation mit γ‐Strahlen keine merkliche Änderung in den physikalischen Eigenschaften aufweist.
Die Tendenz, auch andere schadhafte Gelenke, wie Knie‐, Schulter‐, Ellenbogen, Hand‐ und Fingergelenke, durch eine Prothese zu ersetzen, nimmt stetig zu. Auch bei diesen Konstruktionen bietet sich die Kombination Metall/ultrahochmolekulares Polyäthylen besonders an.
An investigation of Stress corrosion cracking in MgAZ61 alloy in 3.5% NaCl + 2% K2CrO4 aqueous solution at room temperature
Authors: Moccari A. , Shastry C. R. 
Published: December 2004

AbstractEffect of specimen orientation, heat treatment and applied potential on the stress corrosion susceptibility of magnesium AZ61 (Mg‐6.3% Al‐0.5% Zn‐0.20% Mn) alloy in an aqueous 3.5% NaCl + 2% K2CrO4 solution at room temperature was investigated. Stress corrosion times to failure were measured at different values of initial stress intensities using single edge (pre) cracked sheet tensile specimens and a modified tensometer. It was observed that while the specimen orientation has a significant effect on the measured values of stress corrosion threshold stress intensity, KIscc, the effect of varying the quench rate during heat treatment was minimal. Polarization measurements both in stressed and unstressed conditions, failed to reveal any significant effect of the applied stress intensity on the anodic polarization behavior of the alloy. However, measurements made under four different potentiostatic conditions showed a considerable increase in stress corrosion times to failure of the alloy. The results, together with fractographic observations of fractured specimen are discussed in terms of the mechanisms of stress corrosion cracking, in magnesium alloys.
Das Zeitstandverhalten des Stahles X 10 NiCrAlTi 32 20 bei hohen Temperaturen und langen Zeiten
Authors: Büchsenschütz R. , Poweleit B. , Thiessen W. 
Published: December 2004

AbstractDie Ansprüche an die Leistungsfähigkeit der Werkstoffe für Chemieanlagen wachsen ständig. So ist neben dem Übergang zu großen Einheiten nicht nur ein Ansteigen der Drücke und Temperaturen zu verzeichnen, sondern aus technischen und wirtschaftlichen Gründen auch ein optimale Ausnutzung der Werkstoffeigenschaften. Bei den durch Druck und Temperatur höchstbeanspruchten Bauteilen muß die Lebensdauer anhand von Zeitstandfestigkeitskennwerten berechnet werden.An dem austenitischen Werkstoff × 10 NiCrAlTi 32 20 wird versucht, anhand von Zeitstandfestigkeitsuntersuchungen, die im eigenen Langzeitversuch ermittelt sind, eine Aussage über die zeitabhängige Gefügeausbildung zu machen und daraus Schlüsse für den Einsatz dieses Werkstoffes zu ziehen.
Laboratory evaluation of the processing characteristics of rigid PVC compounds
Authors: Bowerman H. H. , McKelvey J. M. 
Published: December 2004

AbstractA small scale screw extruder designed for laboratory extrusion studies has been developed and its performance characteristics with powder‐blended rigid PVC Compounds have been investigated.The use of the extruder in determining the susceptibility of rigid PVC compounds to various die‐induced viscoelastic phenomena (fracture, sharkskin, and swell) is described.An investigation of the phenomenon of “nerve” in rigid PVC extrusions has been carried out. It is concluded that nerve is associated with instabilities in the fluxing process occurring in the transition section of the extruder screw design, the operating variables of the process, and the processing characteristics of the compound.
Thermomechanical studies of polymer deformation part I: A New deformation calorimeter
Authors: Duvdevani I. J. , Biesenberger J. A. , Gogos C. G. 
Published: December 2004

AbstractThe purpose of this paper is to describe a new deformation calorimeter, which is based on differential thermometry and uses a flowing gas stream as a heat transfer medium which allows it to operate under near‐isothermal conditions. Also presented are some preliminary test measurements with a crosslinked polyurethane elastomer and crystalline polybutene‐1.
1969 SPE international award paper. Rheo‐optics on two continents—an example of international cooperation in science
Authors: Stein R. S. 
Published: December 2004

AbstractRheo‐optical techniques for the study of crystalline polymers, developed primarily in the United States and Japan, include dynamic birefringence, X‐ray diffraction, dichroism, light scattering, and fluorescence. These permit the characterization of the rates of orientation of crystals, amorphous regions, and crystalline superstructures. The application of these methods has permitted the formulation of a model for the deformation of crystalline polymers.
Combined tension‐torsion creep experiments on polycarbonate in the nonlinear range
Authors: Lai J. S. Y. , Findley W. N. 
Published: December 2004

AbstractConstant stress creep and recovery experiments were performed in the nonlinear range under combined tension and torsion on a tubular specimen of polycarbonate. Nonlinear viscoelasticity theory was employed to describe the test results. It was found that the first three orders of stress terms and a power function of time adequately described the experimental results. The modified superposition principle satisfactorily predicted the recovery following creep. Recovery was almost complete in several days following two hours of creep.
Mechanical and optical properties of block polymers I. Polyester‐urethanes
Authors: Estes G. M. , Seymour R. W. , Huh D. S. , Cooper S. L. 
Published: December 2004

AbstractThe extraordinary physical properties exhibited by block polymers have been ascribed to the presence of a multiphase microstructure in which the higher modulus phase acts as a quasi‐crosslink or filler particle. Recently, the optical examination of these materials combined with mechanical testing has given investigatiors new insight into this complex morphology. In this investigation, simultaneous stress, strain, and birefringence data have been collected on a block polyester urethane elastomer. Stress‐softening is observed in cyclic stress‐strain experiments, giving rise to significant hysteresis in the stressstrain and birefringence‐stress curves. In these tests, prestrain causes a large increase in the stress‐optical coefficient, but has little effect on the strain‐optical coeffcient. As the temperature is increased, the strain‐optical coefficent decreases while the stress‐optical coefficient increases with the latter exhibiting a larger temperature dependence than predicted by the kinetic theory of rubber elasticity. The good agreement between the mechanical‐optical response of polyester urethanes and that of other block polymer systems provides further evidence of their morphological similarity.
Graft copolymers prepared by anionic techniques–a review
Authors: Heller J. 
Published: December 2004

AbstractThe synthesis of graft copolymers by anionic polymerization techniques is reviewed. Two basic procedures are described. In one a polymer having a reactive end‐group is prepared and allowed to react with another polymer having suitable functional groups. In the second procedure, anions are generated on a preformed polymer backbone and used to initiate the polymerization of subsequently added monomers.
Mathematics of linear‐temperature programmed, first order kinetics in peroxide catalyzed polymerizations
Authors: Willard P. E. , Alvarez M. , Cha L. C. 
Published: December 2004

AbstractA mathematical solution for the Arrhenius temperature dependency for the first‐order decomposition of organic peroxide catalysts has been used to prepare computer‐generated data for concentration vs time when a linearly rising temperature program is used. The resulting plots, of a double exponential nature, are used to show the effects of heating rates and type of organic peroxide on peroxide concentration and polymerization reactions.
Dynamic mechanical properties of polyurethane block polymers
Authors: Huh Dong S. , Cooper Stuart L. 
Published: December 2004

AbstractThe dynamic mechanical properties of polyester and polyether urethane block polymers have been investigated at four frequencies (3.5, 11, 35 and 110 Hz) in the temperature range of — 150 to 200°C. The existence of a two phase structure was demonstrated in these systems by the observation of two major transition regions corresponding to (1) the glass transition temperature (Tg) of the ester or ether soft segments, and to (2) the softening temperature of the aromatic‐urethane hard segments. Several secondary relaxations were observed in addition to the two major relaxations. It was possible to assign molecular mechanisms to each of these relaxations. All relaxation phenomena were greatly influenced by the molecular weight of the prepolymer, weight percent of hard segments, and thermal history. An increase in the molecular weight of the prepolymer above 1,000 at constant hard segment content resulted in a semi‐crystalline material, which possessed a lower Tg for the macroglycol segments. Annealing to enhance crystallinity increased the Tg of the soft segments, consistent with the usual observation in semicrystalline homopolymers. These findings suggest that the relaxation mechanisms of polyurethane block polymers are not only influenced by the degree of crystallinity, but also by the nature of the domain structure.
Some observations on the flow behavior of polyvinyl chloride melts
Authors: Collins E. A. , Metzger A. P. 
Published: December 2004

AbstractMelt studies on PVC systems at elevated temperature or long times are difficult. One consequence is that measurements may be possible only in the non‐Newtonian region. The results indicate that even in this case the melt viscosity can be related exponentially with the weight average molecular weight by the 3.4 power. Since literature data are scarce, attempts were made to extend the range by mixing polymers. This led to the complication of dispersity both on a molecular scale and on a macroscopic level. The latter point is particularly important for PVC studies since the polymers are frequently blended with materials having different viscosities.
Vibration etching, a method of evaluation of photoresist characteristics
Authors: Kolf G. , Laessig W. 
Published: December 2004

AbstractA new method of etching is described, the principle of which is the vibration of the sample being etched within the etchant. Because only small samples can be used this method is not suitable for commercial etching. As a test procedure however it has several advantages: a small volume of etchant (about 100 cc) is sufficient, the pressure of etchant attack can be varied and measured continuously, and the temperature can easily be controlled. Examples are given to demonstrate that vibration etching can be applied for characterization as well as for control of photoresist giving data of etch resistance, etch factor, adhesion, flexibility. Also the characteristics of different etchants and the etch behavior of different metal substrates can easily be compared.
Low temperature dynamic mechanical properties of polyurethane‐polyether block copolymers
Authors: Illinger J. L. , Schneider N. S. , Karasz F. E. 
Published: December 2004

AbstractDynamical mechanical relaxation spectra of a number of polyurethane‐polyether block copolymers have been studied as a function of composition, temperature and frequency. At low temperatures these copolymers are characterized by a high glass‐like modulus which decreases to a much lower typically elastomeric value in a narrow temperature range. The latter is a function in certain cases of the composition of the polymer. The rubbery plateau is maintained up to at least 140°C. In addition, a secondary relaxation is observed around −130°C. These observations can be interpreted in terms of an overall structure consisting of a polyether matrix containing segregated polyurethane domains, the latter serving as physical crosslinks in the system at ambient temperatures and above.
Breaking energies of a nylon series subjected to high‐speed transverse impact
Authors: Wilde A. F. , Ricca J. J. , Rogers J. M. , Cole L. M. 
Published: December 2004

AbstractIn a study of the transient behavior of a series of nylon 6/6 yarns differing systematically in mechanical properties, the effects of high‐speed, transverse missile impact upon yarn specimens were observed by high‐speed photography. The loss in missile kinetic energy was determined directly from the reduction in missile velocity and was studied as a function of yarn tenacity and missile impact velocity. The shape of the missile energy loss curves was due to the partition of missile energy into yarn kinetic energy and yarn strain energy. The missile energy losses and yarn dynamic breaking strains were compared to static breaking energies and breaking strains for these yarns. The observed trends are discussed in terms of the differing yarn tenacities and test rates.
Effect of olefin structure on the vapor‐development of poly (olefin sulfones) under electron irradiation
Authors: Bowden M. J. , Thompson L. F. 
Published: December 2004

AbstractThe rate of vapor‐development of poly(olefin sulfones) subjected to electron beam irradiation is markedly, dependent upon the olefin structure. At room temperature, poly(butene‐1sulfone) and poly(cyclopentene sulfone) vapor‐develop at rates several orders of magnitude lower than, for example, poly(2‐methyl pentene‐1 sulfone). Differences in vapor development rate for the various sulfones are shown to be related to differing rates of depolymerization which, in turn, are related to differences in ceiling temperatures for polymer formation. Kinetic analysis indicates that the mechanism involves random scission followed by depropagation and bimolecular termination.
Porous fabric membranes for soil stabilization and drainage
Authors: Miano Ralph R. 
Published: December 2004

AbstractThis paper briefly reviews the technological status of civil engineering fabrics used for ground stabilization and drainage applications. The theory of how such fabrics work is used to illustrate the advantages of fabric‐containing designs over conventional construction techniques. A drainage project which could not have been completed except at an exorbitant cost without the use of a properly designed filter fabric is detailed, and the economic benefits of using fabrics under ordinary circumstances are also documented. Because fabrics work and because they save money, the outlook for civil engineering fabrics is extremely bright.
Degradation action of water on S‐glass
Authors: Hsu Andrew C. T. , Jemian W. A. , Wilcox R. C. 
Published: December 2004

AbstractGlass fiber reinforced composites have been used to an increasing extent as structural components because of their high strength at relatively low densities. They are more resistant to moisture and weathering than most other structural materials. However, under environments of high humidity and temperature, glass fiber composites with an epoxy or polyester matrix lose a considerable fraction of their.strength‐ after a relatively short time. For high strength glass reinforced composites, the glass filaments are mostly of the S‐glass and E‐glass types. This investigation reports the solvent effect of water on S‐glass rovings (filament strands) and powders. S‐glass is the strongest silicate glass developed in the past decade, the composition of which in weight percent is: A12O3/MgO/SiO2 = 25/10/65. In the temperature range covered (30 to 50°C), analyses of aluminum, magnesium, and silicon in water after different time periods indicate that magnesium is preferentially leached out of S‐glass, either as filaments or as powders, by water. The concentrations of magnesium and silicon in the water reached 2 mg/litre or more depending on the temperature and length of contact time, while the aluminum concentration reached no more than 0.2 mg/litre. Decomposition products of the ingredients present in a composite, including the coupling and curing agents, could further complicate the degradation process. Rate relations are proposed and discussed based on the dissolution data.
Relationship between electron sensitivity and chemical structures of polymers as EB resists: Poly(lactam thioether) as new positive EB resists
Authors: Oguchi Kiyoshi , Yoneyama Sachiko , Sanui Kohei , Ogata Naoya , Takahashi Yoichi , Nakada Tomihiro 
Published: December 2004

AbstractPoly(lactam thioether) was synthesized from tetrahydro‐1,4‐thiazepine‐5(4H)‐one by a ring opening reaction under various conditions and was evaluated as positive electron beam(EB) resist. It was found that poly(lactam thioether) was easily decomposed by EB irradiation. The decomposition by EB exposure may be attributed to cleavage of CS bonds in the polymer chains. The sensitivity of poly(lactam thioether) was influenced by prebake temperature, molecular weight, and developer, a high sensitivity of 5.3 × 10−6 coulomb/cm2 was observed with a good resolution of less than 1 μm. Poly(lactam thioether) showed a high sensitivity and a high resolution, and is suitable as a positive EB resist.
Free radical polymerization models for simulating reactive processing
Authors: Stevenson James K. 
Published: December 2004

AbstractThe generally accepted kinetic mechanism for free radical copolymerization was simplified by various assumptions and restrictions to give several realistic and easily evaluated models for the simulation of industrial molding. Six assumptions, including conversion‐dependent rate coefficients and constant comonomer concentration ratios, were used to obtain a simplified model. Special cases of this simplified model were obtained by the following additional constraints: (1) Restriction C, consecutive inhibition and radical generation reactions; (2) Restriction I, constant initiator decomposition rate; (3) Restriction Z, zero termination rate for free radicals; and (4) Restriction K or P, all rate coefficients independent of conversion or only polymerization rate coefficient dependent on conversion. For various combinations of these restrictions, the time and concentration variables in the simplified model are separated and solved; the separate solutions are then combined in various ways to give models capable of predicting a wide variety of behavior. Many of these models have analytical solutions that greatly facilitate the evaluation of rate constants. Models based on restrictions KCI, PCI, and PCZ are shown to give good agreement with isothermal DSC data plotted as reaction rate versus time and, in a more sensitive test, as reaction rate divided by monomer concentration versus fractional conversion. Because of their predictive ability and ease of evaluating constants. Models PCI and PCZ are recommended for simulating industrial processing; they are particularly well suited for simulating compression molding of sheet molding compound.
Effect of bulk structure of amino silane primer on the strength and durability of aluminum/epoxy joints
Authors: Kaul A. , Sung N. H. , Chin I. J. , Sung C. S. P. 
Published: December 2004

AbstractThe strength and durability in wet environment of aluminum/epoxy/aluminum joints are investigated as a function of structural changes of γ aminopropyltriethoxy silane (γ‐APS) primer at the interface. Both dry and wet strengths exhibit strong dependencies on both the thickness and the extent of drying of γ‐APS prior to joint formation. Generally, dry strength decreases with increasing thickness of γ‐APS primer, and increases with dehydration of γ‐APS at any given thickness. Strength retention of the joints after exposure to water at 55°C also improves dramatically when the adsorbed γ‐APS is extensively dried. These results are analogous to earlier observations with α‐Al2O3/polyethylene joint system. In aluminum joints, porous oxide substrate facilitates the mechanical interlocking mechanism, and its interplay with both the thickness and the extent of cure of γ‐APS is analyzed by characterizing the fractured surfaces using scanning electron microscopy (SEM) electron spectroscopy for chemical analysis (ESCA).
Analysis of dispersion of carbon black in polymeric melts and its effect on compound properties
Authors: Rwei Syang‐Peng , Manas‐Zloczower Ica , Feke Donald L. 
Published: December 2004

AbstractThe dispersion of carbon black agglomerates within melts of polystyrene and high density polyethylene has been investigated. Analysis of the evolution of the fragment size distribution indicates that a coarse rupturing of the agglomerates occurs during the early stages of the dispersion. This is followed by a more gradual erosion of small aggregates from larger fragments. These observations compare quantitatively with results of dispersion studies performed in fluid media having a viscosity two orders of magnitude smaller than that of the polymeric melts. The influence of dispersion quality on certain physical properties of the resulting polymeric compounds, namely UV absorption characteristics and tensile strength properties, is also quantified.
A novel chemically amplified positive deep UV photoresist with significantly reduced sensitivity to environmental contamination
Authors: Chatterjee Subhankar , Jain Sangya , Lu Ping H. , Khanna Dinesh N. , Potvin Robert E. , McCaulley James A. , Rafalko Joseph 
Published: December 2004

Abstractt‐Boc protected Deep‐UV transparent polymers with photoacid generators have been widely investigated as potential positive deep‐UV resist systems. However, utility of these systems is seriously handicapped by environmental contaminants leading to an insoluble “surface skin” formation. Only with a specially controlled environment or by use of an “overcoat” material is the performance of these systems acceptable. We have investigated a series of t‐Boc protected poly(styrene‐maleimide) copolymers and poly(hydroxy styrene) polymers with onium‐salts. Upon incorporation of a special class of organic additive, the surface effects inherent to these positive deep‐UV systems are significantly reduced thereby avoiding any extraneous precaution of protecting the resist surface from a typical manufacturing environment. We evaluated these t‐Boc polymer/onium‐salt systems with different additives under a varied set of processing conditions. In addition, plausible structure‐activity relationship of these additives in controlling the surface effects is presented.