bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acoustic emission behavior of epoxies during tensile loading
Authors: Hollmann K. , Hahn H. T. 
Published: December 2004

AbstractThe acoustic emission behavior during tensile loading of two common epoxy systems of different ductility was investigated at different loading rates. At low threshold voltage, it was possible to register acoustic emissions before the final failure. Only very few emissions were recorded compared with the amount commonly recorded for metals and composite materials. The acoustic emissions detected were of burst‐type, revealing a brittle damage accumulation process. They originated from the initiation and incremental growth of microcracks of stochastic nature. The events occurred before gross yielding and during the final “brittle” failure process. Basically no events were detected between gross yielding and the final failure during which large scale yielding, necking, and stable crack growth took place. The occurrence of events at the different loading rates was strongly influenced by the yielding behavior and fracture toughness, characterized by the yield stress σy and the plane‐strain fracture toughness KIc respectively. KIc was inversely dependent on the total number of events up to gross yielding. The event distribution normalized with respect to the conditions at gross yielding was hardly affected by the loading rate.
Plane‐strain fracture toughness of epoxies at different loading rates
Authors: Hollmann K. , Hahn H. T. 
Published: December 2004

AbstractThe plane‐strain fracture toughness of two common epoxy systems of different ductility were determined at different loading rates, according to ASTM E 399 for metallic materials. The ASTM standard was applicable, but underestimated slightly the specimen thickness required for KIc. KIc decreased with an increasing loading rate and with an increasing yield stress. The fracture surfaces were all very smooth as long as plane‐strain conditions prevailed.
Molecular design of multicomponent polymer systems. XV. Morphology and mechanical behavior of blends of low density polyethylene with acrylonitrile‐butadiene‐styrene (ABS), emulsified by a poly(hydrogenated butadiene‐b‐methyl methacrylate) copolymer
Authors: Fayt R. , Teyssié Ph. 
Published: December 2004

AbstractThe emulsifying activity of a poly(hydrogenated butadiene‐b‐methyl methacrylate) (HPB‐b‐PMMA) copolymer is investigated in incompatible blends of a low density polyethylene and poly(styrene‐co‐acrylonitrile) resins (mainly ABS) prepared in the melt state on a two‐roll mill. Optical and scanning electron microscopy observations clearly demonstrate that a moderate amount of copolymer (5 wt %) very significantly decreases the particle size and enhances interfacial adhesion. The block copolymer is also responsible for a strong improvement in both the ductility and Charpy impact resistance of PE/ABS blends.
Effect of titanate coupling agents on mechanical properties of mica‐filled polypropylene
Authors: Bajaj Pushpa , Jha N. K. , Jha Rajiv K. 
Published: December 2004

AbstractThe application of titanate coupling agents for the surface modification of mica filler and its reinforcement in polypropylene (PP) has been directed towards improvement in mechanical properties. Four titanate coupling agents, namely neoalkoxy tri(dioctylpyrophosphato) titanate (C1), neoalkoxy trineodecanoyl titanate (C2); bis‐(acetylacetonato)distearato titanate (C3), and bis‐(acetylacetonato)dipalmitato titanate (C4) were used in the present investigation. Mica powder (10 μm particle size) was coated with these coupling agents of varying concentration (0.5 to 1 % on the weight of filler) and then blended with polypropylene powder of 10 melt flow index. The mica (10 to 50 wt. %) filled polypropylene samples with and without coupling agents, were injection molded and the mechanical properties of the specimens tested. There is an improvement in the tensile, flexural, and impact strength of PP/mica samples coupled with titanates. The best performance in terms of yield stress and flexural strength was observed in PP/mica samples having 0.7% C1, titanate coupling agent. The fracture behavior of mica filled PP has also been studied using a scanning electron microscope.
Network mechanical properties of amine‐cured epoxies
Authors: Vratsanos Menas S. , Farris Richard J. 
Published: December 2004

AbstractThe technique of Impulse Viscoelasticity was used to characterize the network mechanical properties of amine‐cured epoxies during cure. The effects of amine molecular weight, functionality and stoichiometry were investigated. Among the properties which were obtained were the equilibrium tensile modulus, gelation time, cure and thermal stresses, volumetric changes during cure, glass transition temperature, thermal expansion coefficient, and molecular weight between cress‐links. It was found that these networks cured elastically and agreed closely with the predictions of rubber elasticity theory over a wide range of crosslink densities.
Highly sensitive novolak‐based X‐ray positive resist
Authors: Lingnau J. , Dammel R. , Theis J. 
Published: December 2004

AbstractThe application of X‐Ray lithography in mass production of devices is only economically viable if resist materials of highest sensitivity can be provided. Chemical amplification is the key concept to achieve such performance. It is outlined for a highly sensitive three component positive tone X‐Ray resist, consisting of a Novolak binder matrix, a starter compound, which—on X‐Ray exposure—yields an acid, which catalytically decomposes a dissolution inhibitor. Resist performance is discussed in terms of reaction kinetics and their implications on resist response, simulation, and handling procedures.
Silicon containing photoresists for half micron lithography
Authors: Sezi R. , Sebald M. , Leuschner R. 
Published: December 2004

AbstractSeveral silicon containing topresists for bilayer oxygen reactive ion etching systems were developed and examined. Each topresist consists of a silicon containing alkaline soluble copolymer and a 2‐diazo‐1‐naphthalenone‐4‐sulphonic acid ester photoactive compond (PAC). Half micron structures in the topresist were obtained with two different resist systems through deep‐UV (257 nm) or iline exposure. The etch rate ratios (planarizing layer:copolymer) vary between 7:1 and 13:1 under anisotropic etching conditions. Linewidth loss during oxygen RIE (reactive ion etching) pattern transfer is a problem for resists containing about 10% silicon, but equal lines and spaces after etching can be obtained through the use of thick topresists or linewidth bias in the topresist prior to etching.
The chemistry of g‐line photoresist processes
Authors: Vollenbroek F. A. , Nijssen W. P. M. , Mutsaers C. M. J. , Geomini M. J. H. J. , Reuhman M. E. , Visser R. J. 
Published: December 2004

AbstractThe chemistry that underlies positive imaging, Image Reversal (ImRe) and Built In Mask (BIM), has been investigated. For this purpose the photoactive compound 2, 1 ‐diazonaphthoquinone‐5‐(4‐cumylphenyl)‐sulfonate (PAC‐5), the corresponding indenecarboxylic acid (ICA‐5) and the decarboxylated derivative of ICA‐5 (indene), were isolated and characterized. The study revealed that dissolution of ICA‐5 in aqueous base developers gives rise to the formation of an indenyl carboxylate dianion, which decarboxylates in several hours. In the case that ICA‐5 is dissolved in weakly alkaline media or in organic solvents such as methanol, the formation of this ion does not occur, but the rate of decarboxylation is almost the same. It is suggested that the decarboxylation reaction proceeds via the indene carboxylate monoanion, which reacts to indenyl anion. The latter is a strong base and is readily protonated to give indene (two isomers). In the case of aqueous base this leads to precipitation of the indene. In agreement with the finding that the indene derived from ICA‐5 does not dissolve in aqueous base developers, it was found that mixing indenes into novolak has a considerable inhibitive effect on the dissolution rate of a layer of this material in aqueous base. After a bake (in ImRe this would be the reversal bake), the dissolution rate is almost the same as for unexposed photoresist. Similar experiments with mixtures of novolak and indenecarboxylic acid revealed that there is no difference in the dissolution rate of such layers as compared with exposed photoresist. This excludes the putative effect of porosity, caused by nitrogen extrusion. In the case that 1‐phenyl‐3‐morpholinotriazene is added to the photoresist (in order to produce a dye in the BIM concept), azo‐dyes are formed by coupling of diazonium ions on the 1‐ and 3‐position of 3‐indenecarboxylic acid. The paper starts with a brief review of the mechanisms of photolysis of 2, 1 ‐diazonaphthoqui nones, as have been proposed in the literature. Although the formation of ketene as an intermediate is generally accepted, there appears to be no consensus about the existence of carbene.
Characterization of thermal behavior and kinetics of crystallization of a thermotropic rigid‐chain copolymer
Authors: Kamal M. R. , Khennache O. , Goyal S. K. 
Published: December 2004

AbstractThermal analysis was employed to estimate the heat of transition, equilibrium melting temperature and surface free energy of a thermotropic liquid crystal copolyester resin (70 mol% p‐hydroxybenzoic acid and 30 mol% 2,6‐hydroxynaphthoic acid). Specific heats and melting and crystallization behavior were evaluated using differential scanning calorimetry (DSC). Experiments over a wide range of cooling rates indicate two different crystallization processes: a rapid crystallization process and a slow crystallization process. The kinetics of the rapid crystallization process were evaluated using a non‐isothermal method. The analysis indicates that the rapid crystallization process can be suitably described by the non‐isothermal Avrami equation. The Avrami exponent is found to be equal to 2, which is in agreement with the nucleation and growth mechanism of the rigid rodlike molecules. The kinetics of the slow crystallization process, which were studied using an isothermal method, indicate that the degree of crystallinity varies linearly with log(time). The equilibrium melting temperature for this process is found to be 372°C. The Arrhenius plot yields a linear relationship in the lower temperature range.
The effects of cure temperature on the thermomechanical properties of UV curable coatings
Authors: Overton B. J. , Taylor C. R. , Muller A. J. 
Published: December 2004

AbstractA method is presented to study the mechanical behavior of soft, UV curable coating material as a function of temperature of the prepolymer at cure. For such materials, the crosslink density (hence, equilibrium modulus) is found to decrease with increasing cure temperature. The three primary coatings are: a polyurethane acrylate with a nominal equilibrium tensile modulus of 200 psi, a polyurethane acrylate with a nominal equilibrium modulus of 1200 psi, and a non‐urethane acrylate with a nominal equilibrium tensile modulus of 60 psi.
Fire resistant optical cables with special plastic coated fibers
Authors: Suzuki H. , Tsujita T. , Shamoto N. , Inada K. 
Published: December 2004

AbstractIt is important to prevent transmission loss increase of optical fiber cables during a fire and fire fighting. One of the main reasons for the loss increase in a fire is the expansion and shrinkage of polymers used in optical fiber cables. The authors have developed a fire resistant optical fiber cable by studying the behavior of coating materials and coated fibers at high temperature. Polymer types investigated are thermoplastics, engineering plastics, and UV cured plastics. The fire resistant optical fibers are coated with a polymer which rapidly produces a carbonized layer by exposure to heat. The rapid carbonizing has the effect of reducing expansion and shrinkage. Besides the coating, the coated fiber is surrounded by carbon yarn to prevent breakage of the fiber. The fire resistant optical fiber cable passed the fire test at 840°C for 30 minutes and VTFT specified IEEE 383, without any breakage of the fibers. The optical loss of the fibers scarcely changed during the tests and after the tests. This paper presents the studies of coating materials and coated fibers at high temperature, the structure and properties of the coated fiber and characteristics of the fire resistant optical fiber cable.
Polymers for optoelectronics
Authors: Kaino Toshikuni , Katayama Yuzo 
Published: December 2004

AbstractThis paper discusses polymers for optoelectronics, especially plastic optical fibers (POFs) for near‐infrared (near‐IR) use and polymeric nonlinear optical materials expected for use as switching devices. Near‐IR transmissible plastic optical fibers are investigated using fluorination and deuteration for conventional polymers. Among them pentafluoro‐trideutero‐styrene polymer core POF has excellent transparency in the near‐IR region even after water vapor absorption. Nonlinear optical polymeric materials with excellent processibilities are also investigated. The third‐order nonlinear optical susceptibility of poly‐aromatic vinylene thin film was measured and revealed to have a higher susceptibility than previously reported.
Optical fiber chemical sensors utilizing dye‐doped silicone polymer claddings
Authors: Blyler L. L. , Lieberman R. A. , Cohen L. G. , Ferrara J. A. , Macchesney J. B. 
Published: December 2004

AbstractTransparent dimethyl siloxane network polymers with refractive indices near 1.40 may be applied to fused silica fibers (n = 1.458) as they are drawn to produce plastic‐clad silica (PCS) optical fibers. The evanescent tail of the light energy propagating in the core of such fibers extends into the silicone cladding, where it interacts with chemical species present in the polymer. If the silicone is doped with a dye, the absorption spectrum or fluorescence spectrum of the dye is reflected in the transmission spectrum of the fiber. Further, if the dye changes its absorption spectrum or fluorescence spectrum as a result of diffusion of a chemical species into the silicone, the change is detectable in the fiber output. The polymer material properties which determine the performance of these sensors are described, along with examples of sensors for ammonia and oxygen which utilize either color changing or fluorescent dyes.
Thermal interactions in oriented polymeric materials: Shrinkage, crystallization, and melting
Authors: Sun D. C. , Magill J. H. 
Published: December 2004

AbstractThermal analysis of oriented polymers involves several transitional processes which may be coupled in a complex way. The disorientation process that occurs during heating is often accompanied by dimensional shrinkage which may occur in both amorphous and crystalline oriented polymers. From differential scanning calorimetry (DSC) measurements it has been determined that shrinkage is an exothermic process. In amorphous atactic polystyrene (PS), hot drawn uniaxially, the shrinkage occurs just above Tg. In triaxially oriented polyethylene (PE) and isotactic polypropylene (iPP), shrinkage and melting take place concomitantly, producing multiple melting peaks. In rolltruded (and also in biaxially oriented) poly(ethyleneterephthalate) (PET) films, shrinkage and crystallization are found to be coupled and to occur between Tg and Tm upon heating. If the enthalpy contribution due to shrinkage is ignored, it follows that crystallinities determined by DSC are incorrect. In this study, the influence of shrinkage upon transitional changes in oriented polymers is investigated in a systematic manner.
Temperature‐dependent mechanical properties and constitutive equation of cellulose nitrate
Authors: Nishitani T. , Ogura H. 
Published: December 2004

AbstractThe strain‐time response under tensile loading (creep tests) and the stress strain response under constant tensile stress rate (proportional loading tests) have been evaluated at 4 temperatures 20, 45, 55, and 65°C, for samples of cellulose nitrate. A time‐dependent constitutive equation (or stress‐strain relation) for the nonlinear visco‐elastic material is deduced from invariant theory with a hypothesis of a creep potential. The procedure for determining the seven material constants involved in the deduced constitutive equation is described for the creep and proportional loading tests and the variation of these constants with temperature is presented. The deduced constitutive equation gives good agreement with the actual observations for the creep and proportional loading tests, independent of the values of temperature, creep stress, or stress rate.
Curing and constitutive relationships for polyester mortar
Authors: Vipulanandan C. 
Published: December 2004

AbstractThe compressive and tensile properties of polyester mortar were studied under various curing conditions, temperature, and strain rate. The curing temperature was varied from room temperature to 80°C. The behavior of polyester mortar was studied using a uniform sand with strain rate and temperature varied between 0.01 to 6 percent strain per minute and 22°C and 120°C, respectively. The strength, failure strain, modulus and stress‐strain relationships of polyester mortar are influenced by the curing method, testing temperature, and strain rate to varying degrees. The influence of test variables on the mechanical properties of polyester mortar are quantified. Pretreating the aggregates with a silane coupling agent further enhances the compressive and tensile strength of the mortar. The compressive modulus and splitting tensile strength of polyester mortar are related to the compressive strength. A constitutive model is used to predict the compressive stress‐strain behavior of polyester mortar.
Thickness effects in the vibration welding of polycarbonate
Authors: Stokes Vijay K. 
Published: December 2004

AbstractIn vibration welding of thermoplastics, frictional work done by vibrating two parts under pressure, along their common interface, is used to generate heat to effect a weld. Past work on welding characterized the effects of weld parameters such as the weld frequency, the weld pressure, and the weld time, on the welding process and weld strength, and showed that the most important parameter affecting weld strength Is the weld penetration—the decrease in the distance between the parts being welded that is caused by lateral outflow of material in the molten film. However, those weld studies were based on specimens of constant nominal thickness (6.35 mm, 0.25 in). This paper is concerned with the effects of specimen thickness on the weld process and weld strength.
Time and temperature dependent sorption in poly‐ether‐ether‐ketone (PEEK)
Authors: Mensitieri G. , Del Nobile M. A. , Apicella A. , Nicolais L. 
Published: December 2004

AbstractThe possible multimodal sorption mechanisms in glassy amorphous poly‐ether‐ether‐ketone (PEEK) are presented. By varying the penetrant‐polymer affinity, experimental temperature, and external solvent activity, a broad range of sorption behaviors from ideal Fickian diffusion to limiting relaxation controlled kinetics is observed. In particular, water, methylene chloride, and n‐heptane sorption kinetics are analyzed and interpreted on the basis of the multiple transport mechanisms. Low uptake liquid n‐heptane sorption follows ordinary Fickian diffusion. Analogously, water vapor at low activity, is sorbed in small amounts in the same limiting mode while, at higher activities, the moderately higher penetrant uptakes induce slow relaxation coupled with ideal Fickian diffusion. The highly interacting methylene chloride leads to ideal Fickian diffusion only at very low activities, while anomalous non‐ideal Fickian diffusion and limiting Case II and diffusion controlled swelling are observed at moderate and at high solvent activities, respectively. Limiting Case II sorption of methylene chloride in PEEK has been observed only at a very low temperature (−32°C). The optical microscopy observations of cryogenically fractured samples contacted with liquid methylene chloride at 5, 20 and 36°C revealed the presence of a sharp front moving linearly with the square root of time. Solvent induced crystallization in methylene chloride swollen samples was detected by means of differential scanning calorimetry (DSC) and wide angle X‐ray scattering (WAXS). Finally, sorption from liquid methylene chloride/n‐heptane solutions with varying compositions are presented. The progressive increase of the more high sorbing methylene chloride concentration in the solutions, leads to the same wide variety of sorption behavior observed in the methylene chloride vapor sorptions. The gas chromatographic (GC) analysis indicated that the presence of methylene chloride enhanced the n‐heptane sorption in the polymer.
The breaking strength of perfect polymer fibers
Authors: Smith K. J. 
Published: December 2004

AbstractThe breaking strength, strain at break, and work to rupture of perfect fibers prepared with polymers of finite molecular weight are calculated by treating the perfect fiber as a stressed crystal undergoing a crystal‐melt phase transition. In this view, a tensile load destabilizes the crystal and depresses its melting point. When the load is sufficient to lower the melting temperature to the ambient condition the fiber melts—i.e., fails. The theoretical equations (extremely simple) are applied to several common polymer fibers. The maximum tensile strength of polyethylene, for example, is calculated to be 7 to 9 GPa, in good agreement with current experimental results.
Electrical and dielectric properties of segregated carbon black–polyethylene systems
Authors: Yacubowicz J. , Narkis M. , Benguigui L. 
Published: December 2004

AbstractThe electrical and dielectric properties of compression‐molded segregated polyethylene‐carbon black mixtures are described in the frequency range between 10 and 8000 kHz as a function of frequency, temperature, and carbon black loading. The segregated systems investigated exhibit insulator‐conductor transitions in the range 0.25–0.65% (volume/volume) carbon black. The dielectric constant and the dissipation factor of the conductive samples are relatively very high in the frequency range studied. The dielectric constant increased sharply with the carbon black concentration, and then increased moderately beyond the insulator‐conductor transition. The dissipation factor‐concentration curves for different carbon blacks show maximum values in the vicinity of the critical concentration values. The dielectric properties of these systems are discussed in terms of interfacial Maxwell‐Wagner polarization effects.
A free radical copolymerization model for simulating reactive processing of unsaturated polyester resins
Authors: Huang Y. J. , Fan J. D. , Lee L. J. 
Published: December 2004

AbstractA free radical copolymerization model is proposed for simulating the reaction rates and conversions of styrene monomer and unsaturated polyester resins during curing. This model is based on film theory in which the rate constants reflect both reaction and diffusion resistances. Differential scanning calorimetry in combination with Fourier transform infrared spectroscopy is used to measure the overall and individual reactivities of reacting species. Model parameters are determined from experimental data. The applicability of this model is demonstrated in a cure simulation.