bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plastic molded single and ribbon type optical fiber connectors
Authors: Inada K. , Yokosuka H. 
Published: December 2004

AbstractTwo types of precisely molded fiber optic connectors have been developed. They are a cylindrical ferrule connector for a single fiber and a five‐fiber array connector for a tape fiber. The connectors are made by using a transfer molding technique with a silica‐filled thermosetting epoxy resin. The resin has low pressure and high melt‐flow characteristics, high dimensional accuracy, and high stability. The single fiber connector consists of a pair of plastic molded ferrules, a slitted alignment sleeve, and a plate spring. A fiber is inserted into a ferrule capillary and is fixed with adhesive. Then the fiber end face positioned in the center of the ferrule is polished to have a mirror surface. The five‐fiber connector consists of a couple of precisely molded ferrules, two alignment pins, and a plate spring. The five‐fiber ribbon is inserted into fiber receiving capillaries, of the ferrule, and fixed with adhesive. The fiber end faces on the ferrule mating face are polished to have a mirror face. In order to realize a low‐loss connection, the alignment pin holes and five‐fiber positioning capillaries on the ferrule mating face must be molded precisely. Various kinds of reliability tests on the connectors were conducted. All the results obtained proved that the connectors have entirely satisfactory properties for practical use. The connectors are now widely used in an optical fiber subscriber network.
Materials for nonlinear optics‐orientationally ordered polymer films
Authors: Sohn J. E. , Singer K. D. , Kuzyk M. G. , Holland W. R. , Katz H. E. , Dirk C. W. , Schilling M. L. 
Published: December 2004

AbstractEmerging guided‐wave integrated optical technologies require suitable active devices and optical interconnects. Certain organic molecular materials possess the required optical nonlinearities for application in active devices. Glassy polymers, such as poly(methyl methacrylate), have been used to fabricate high optical quality passive structures. For application in integrated optics, requirements include high optical quality (low scattering and absorption losses), low dielectric constant, and suitable fabrication techniques.We describe the preparation and optical properties of a new material, class, poled polymer glasses, which combines the attractive properties of the optical nonlinearities of organic molecules and the optical quality of polymer glasses. These materials are formed by incorporating organic compounds possessing large optical nonlinearities into a host material lacking long‐range order. The orientational order is imparted to the composite system by applying a strong electric field at a temperature above the glass transition temperature, where molecular motion is enhanced, thereby aligning the optically nonlinear dopant molecules. By cooling the material through the phase transition with the field still applied, the orientational order is frozen in, and the composite material possesses second‐order nonlinear optical properties.
Effect of temperature and shear rate on polyisoimide solution viscosity
Authors: Levinson William , Czornyj George , Capo Donald , McMahon Jeffrey 
Published: December 2004

AbstractThe following models describe the effect of temperature and shear rate on the viscosity of polyisoimide solutions.

Data was obtained for 20, 30, and 40% polyisoimide solutions in 20:80 tetrahydrofuran/diglyme and for a 30% solution in N‐methyl‐pyrrolidone at temperatures of 25°, 35°, 55°, and 75°C. The measurements were taken on a Brookfield cone and plate viscometer at shear rates ranging from 9.59 to 383.4 reciprocal seconds. Experimental data fits model (1) reasonably well. In some cases, model (2) provides a better fit. This model accounts for temperature dependencies in the power law shear‐thinning exponent.The coefficients β depend on the material lot that is being tested even though the lot molecular weights are very close. Slight differences in acid functional group concentrations for this particular material are a possible explanation.
On the slip phenomenon of polymeric solutions through capillaries
Authors: De Vargas L. , Manero O. 
Published: December 2004

AbstractThe slip phenomenon through capillaries has been analyzed experimentally using solutions of polyacrylamide and xanthan gum. These polymeric solutions present macromolecules with different conformations in flow. Attention was given to the influence of molecular conformation of those polymeric solutions upon the slip velocity. Considerable variations on the slip velocity were observed when the ionic strength of the xanthan solution was increased and also when the material of the capillaries was changed. Measured magnitudes were much larger in the xanthan solutions than those observed in the polyacrylamide solution.
Effects of physical aging on dynamic mechanical and transient properties of polyetheretherketone
Authors: Wang S. F. , Ogale A. A. 
Published: December 2004

AbstractThe effects of physical aging on dynamic mechanical and transient stress‐relaxation properties of a high performance thermoplastic, polyetheretherketone (PEEK), are reported in this study. The aging effects are shown to be physical effects (and not chemical degradation) by establishing thermoreversibility of the aging process. The unique aspect of the present study is the simultaneous investigation of both dynamic and transient properties in the same mode of loading, namely, in shear. The influence of continuous dynamic deformation on the aging process is also reported. The results for the aging rate, obtained from dynamic and transient testing under shear load, agree with one another and verify the equivalence of dynamic and transient viscoelastic properties. However, these results differ significantly from the aging rate results reported in an earlier study for tensile loading. A possible explanation for the difference has been proposed in terms of the volume change that accompanies tensile creep deformation.
Modeling the chemorheology of thermosetting resins during processing
Authors: Martin G. C. , Tungare A. V. , Gotro J. T. 
Published: December 2004

AbstractThe curing conditions determine the rheological changes in the resin during the lamination of prepregs into multilayered circuit boards. In order to specify the optimum curing conditions during lamination, it is necessary to understand the rheology of the resin as it cures. In this study, the chemorheological behavior of two commercial epoxy resins and one cyanate‐based resin was characterized using an engineering model for the resin viscosity. A linear regression technique was used to evaluate the model parameters from the conditions at the minimum viscosity obtained during resin cures at constant heating rates. The technique was extended to predict the minimum viscosities reached by the resins when subjected to temperature conditions commonly encountered during lamination. The utility of the technique for specifying the curing conditions necessary to have a desired resin flow during lamination and for selecting resin systems for lamination based upon chemorheology has been demonstrated.
An experimental study of the dynamics of the curing process of sheet molding compound (SMC) paste
Authors: Kau Hua‐Tie 
Published: December 2004

AbstractThe dynamic curing behavior of sheet molding compound (SMC) has been investigated by using a cylindrical cure reactor. Both thermal and mechanical responses were determined for R‐25 SMC paste. The responses from this material were analyzed to determine the chemical and physical transformations that occur during the SMC molding process. The thermal response was obtained from a thermocouple placed along the centerline of the paste sample in the cure reactor. The thermal history at this location shows distinctive stages associated with heat transfer and crosslinking reactions during the cure cycle. The R‐25 paste has a precure time of 160 seconds, a reaction time of 25 seconds, and a temperature rise of 134°C. The mechanical response describes the volume change and the pressure of the paste. The displacement curve shows volume changes due to thermal expansion, cure shrinkage, and thermal contraction during the course of a cure cycle. We found a less than 1% shrinkage during the reaction of the R‐25 paste. The pressure response of the paste was found to parallel the volume transformation, although it also is strongly influenced by mechanical interactions between the press and the paste.
Repairability of plastic automobile bumpers by hot gas welding
Authors: Atkinson J. R. , Turner B. E. 
Published: December 2004

AbstractProblems associated with the repair of fractured plastic car bumpers by traditional hot gas welding have been identified. In particular, interfacial cracks arising due to contraction stresses, weld pores, root notches, and voids in filler rods have been observed. These result in welds with inferior mechanical properties. Even so the impact properties and strength of plastic bumpers which were fractured and have been repaired by hot gas welding are likely to be acceptable for the purposes that the bumpers are intended. We have considered three materials: a polycarbonate/polyester blend, poly(butylene terephthalate), and an ethylene‐propylene‐diene rubber. Improvements in weld strength and interfacial bonding arise if a heated roller immediately following the welding torch is used to consolidate and compress the molten plastic. Porosity is reduced if the hot gas can escape easily from beneath the weld.
Synthesis and physical behavior of siloxane modified polyimides
Authors: Arnold C. A. , Summers J. D. , McGrath J. E. 
Published: December 2004

AbstractA variety of thermoplastic fully imidized poly(imide siloxane) segmented copolymers with useful thermal and mechanical properties have been prepared. Other interesting properties described are the materials' hydrophobic character, surface domination, UV stability, and atomic oxygen plasma resistance.
Characterization and cold compaction of polyether‐etherketone powders
Authors: Reilly J. J. , Kamel I. L. 
Published: December 2004

AbstractThis study deals with the characterization and cold compaction of polyetheretherketone (PEEK) powders. Four different types of PEEK powders which are commercially available from Imperial Chemical Industries (ICI) were characterized for density, crystallinity, particle size, particle size distribution, and particle morphology. Fine and coarse size powders of a low viscosity grade (150PF and 150P) and similar powders of a high viscosity grade (450PF and 450P) were processed. Compaction was successful at room temperature using the 150 grade powders but not with the 450 grade powders. Compressibility curves were obtained at room temperature for the 150 grade powders and their post‐compaction viscoelastic recoveries were measured. The coarse and fine size 150 grade powders reached relative plateau densities of 95.8% and 95.1%, respectively, when compacted at pressures exceeding 300 MPa. These high densification values at room temperature were associated with minimal post‐compaction viscoelastic recoveries and as‐compacted strengths as high as 8.9 MPa. A modified densification parameter (DP*) was developed based on the plastic deformation of the crystalline regions alone. This new dimensionless parameter, DP*, demonstrated a better fit of all the compaction data. The transverse rupture strength and the green density data are presented and explained in terms of this DP*.
Structure‐property relationships in rubber‐toughened epoxies
Authors: Hwang J.‐F. , Manson J. A. , Hertzberg R. W. , Miller G. A. , Sperling L. H. 
Published: December 2004

AbstractEpoxies toughened with two reactive liquid rubbers, an epoxy‐terminated butadiene acrylonitrile rubber (ETBN) and an amino‐terminated butadiene acrylonitrile rubber (ATBN), were prepared and studied in terms of their structure property relationships. A two‐phase structure was formed, consisting of spherical rubber particles dispersed in an epoxy matrix. A broad distribution of rubber particles was observed in all the materials with most of the particles ranging in size from 1 to 4 μm, but some particles exceeding 20 μm were also found. Impact strength, plane strain fracture toughness (KIC), and fracture energy (GIC) were increased, while Young's modulus and yield strength decreased slightly with increasing rubber content and volume fraction of the dispersed phase. Both GIC and KIC were found to increase with increasing apparent molecular weight between crosslinks and decreasing yield strength. The increased size of the plastic zone at the crack tip associated with decreasing yield strength could be the cause of the increased toughness. An ATBN‐toughened system containing the greatest amount of epoxy sub‐inclusion in the rubbery phase demonstrated the best fracture toughness in this series. In the present systems, rubber‐enhanced shear deformation of the matrix is considered to be the major toughening mechanism. Curing conditions and the miscibility between the liquid rubber and the epoxy resin determine the phase morphology of the resulting two‐phase systems. Kerner's equation successfully describes the modulus dependence on volume fraction for the two‐phase epoxy materials.
Biaxially oriented films prepared from poly(vinyl chloride)/poly(methyl methacrylate co imide) blends
Authors: Kotnis Mahesh A. , Spruiell Joseph E. 
Published: December 2004

AbstractA study was conducted of blends of poly(vinyl chloride) (PVC) with a poly(methyl methacrylate co imide). The latter polymer was found to be miscible in PVC and to raise the glass transition temperature of the blend. Blends of all compositions could be oriented, but the processing temperature increased in proportion with Tg. For a given blend composition, orientation increased with increasing stretch ratio and strain rate and with decreasing stretch temperature. Increasing copolyimide content and increasing orientation generally lead to improved mechanical properties, though the blends containing high levels of copolyimide exhibited low ductilities.
Craze dissemination during fatigue fracture in polystyrene
Authors: Botsis J. , Gregory B. L. 
Published: December 2004

AbstractResults of studies on fatigue fracture in polystyrene are reported. Experiments were carried out on tension‐tension single edge notched specimens, 0.25 mm thick. Macroscopic studies involved the propagation of the crack and its associated active zone (or the so‐called process zone) evolution. Microscopic studies consisted of fracture surface examination and quantitative characterization of the crazing distribution along the trailing edge and within the active zone. The width and length of the active zone increased monotonically during the quasi‐static phase of crack layer growth. The crack growth kinetics followed an S‐shaped curve. Analysis of crazing distribution showed that; (i) the distribution of crazing along the trailing edge of the active zone is related by a scaling parameter, (ii) the average crazing density along the trailing edge as well as within the active zone is constant, (iii) the specific energy of crazing evaluated here compares well with previously reported data. The results of this work support the form of self similarity of damage evolution adopted by the crack layer model, and that the specific energy of damage is a material constant.
Statistical model for predicting the strength of solid‐filled rubbers
Authors: Chen U. D. , So H. 
Published: December 2004

AbstractThe tensile strength of solid‐filled rubbers is predicted by the statistical model proposed in this paper, by which the maximum area fraction of the solid filler in a representative cube is calculated. The minimum net cross‐section area of the rubber matrix is thus obtained, and this is used to calculate the reduction in strength of the compound in comparison to that of the unfilled rubber. The prediction is then tested by experiments using hydroxyl‐terminated polybutadiene (HTPB) filled with glass spheres. After curing, tensile specimens were cut from sheets and exposed to humidity‐controlled environments so as to debond the filler particles from the rubber matrix, and were tested in tension. The experimental results were found consistent with the predictions.
Statistical procedure to identify sources of extrusion line variation
Authors: Stevenson J. F. 
Published: December 2004

AbstractA statistical procedure is proposed to identify sources of variation in the operation of complex extrusion lines. This approach involves separating multichannel extrusion line data, as necessary, into appropriate time scales; identifying significant cross correlations among various pairs of channels; and then comparing the pattern of the observed cross correlations with those expected for possible sources of variation. This procedure is able to detect unsuspected relationships among processing variables and to provide a rational basis for upgrading extrusion line performance. The pattern generation and comparison methodology could also be useful for expert systems. To illustrate the procedure, 11 channels of data from a dual extrusion line with metered feed were collected and analyzed. Since two sources of variation on different time scales were evident, the data were divided into long‐term and short‐term components using statistical methods. Cross correlation functions among pairs of variables were used to estimate offset times and identify variables that were significantly correlated. To be considered significant, the extremum in the cross correlation function had to occur at a realistic time offset and have an absolute value exceeding a prescribed threshold. The observed cross correlations between pairs of short‐term and of long‐term components were compared with the expected correlation patterns for typical process disturbances. By this procedure, the cause of the short‐term trends was identified as surging primarily in the larger extruder; a particular long‐term trend was attributed to a property change in the feed material to the smaller extruder. This analysis formed the basis for a novel process control device to minimize the consequences of short‐term variation in extruder output.
Strength and bonding mechanisms in vibration‐welded polycarbonate to polyetherimide joints
Authors: Stokes V. K. , Hobbs S. Y. 
Published: December 2004

AbstractUnder the right conditions, high strengths are shown to be achievable in vibration welded polycarbonate to polyetherimide Joints. While welding of thermoplastic interfaces of the same material can be understood in terms of interchain diffusion at elevated temperatures, this mechanism is severely limited in the case of dissimilar materials. Scanning electron microscopy is used to show that part of the bond strength in such dissimilar materials results from mechanical interlocking of the two polymers, which is caused by viscous mixing. The effects of the weld parameters on the weld morphology are considered in detail.
Microspheres and microcapsules: A survey of manufacturing techniques. Part 1: Suspension cross‐linking
Authors: Arshady R. 
Published: December 2004

AbstractA methodological survey of preparation of microspheres and microcapsules by suspension cross‐linking is presented. Thus, basic features of suspension cross‐linking, i.e., the formation of small droplets of a polymer solution (or melt) in an immiscible liquid followed by hardening of these droplets by covalent cross‐linking, are discussed. Typical microspherical and microcapsular products manufactured by suspension cross‐linking of naturally occurring and preformed synthetic polymers, including agarose and cellulose beads, albumin microspheres and microcapsules, polystyrene beads and epoxy resin microcapsules, are described. Manufacturing parameters controlling microsphere/microcapsule characteristics are also briefly outlined.
3‐D structure‐property relationships in rolltruded polymers. Part II: Anisotropic yielding and deformation in triaxially oriented polymers
Authors: Sun D. C. , Berg E. M. , Magill J. H. 
Published: December 2004

AbstractRolltrusion, a single step solid state deformation process, has been successfully applied to isotactic poly(propylene), iPP, to produce unique 3‐D properties. Mechanical property enhancement not only occurs in the principal draw direction, but also in the transverse directions. A systematic series of standard (ASTM) tensile and compressive experiments were made on well oriented materials supporting this claim. Tensile testing was also performed on dumb‐bell shaped specimens cut at various angles to the main deformation direction. A variety of observations were made during testing. Deformation bands, anisotropic yielding, and ductile‐to‐brittle behavior were observed. These results are presented along with a morphological model that has been developed to account for the behavior of these unique triaxially oriented polymers.
Viscous dissipation effect on solidification of a liquid onto a tube wall
Authors: Ahmadian M. Taghi , Burmeister Louis C. 
Published: December 2004

AbstractThe effect of viscous dissipation on solidification onto the inner surface of a straight circular tube of a liquid flowing laminarly with a specified volumetric rate is analytically determined. Steady conditions and a constant tube wall temperature below the solidification temperature of the liquid are assumed. Solutions for the thickness of the solidified shell and for the pressure drop are obtained. The pressure gradient versus volumetric flow rate curve exhibits a minimum, suggesting that it might be possible to design runners for injection molding machines to have a minimum pressure drop if the volumetric flow rate is specified.
Optimization of injection molding design. Part I: Gate location optimization
Authors: Pandelidis Ioannis , Zou Qin 
Published: December 2004

AbstractThe placement of a gate in an injection mold is one of the most important variables of the total mold design. The quality of the molded part is greatly affected by the gate location, because it influences the manner in which the plastic flows into the mold cavity. Some defects, such as weldline and overpack, can be effectively controlled only by the gate location. Therefore, the product quality can be greatly improved by determining the optimum gate location. In this paper, we develop a general methodology for gate location optimization. We first quantify quality in terms of flow simulation outputs. We can thus assess detrimental effects such as warpage and dimensional instability as a function of the independent variable, which is in this case the gate location. Next we develop methods to search for the optimum gate location. The search method introduced in this paper is a method that combines a deterministic hill climbing search with a stochastic annealing search method. The method is appropriately called simulated annealing and hill climbing (SANHIL). The criteria used for evaluation during the search process are a function of the flow simulation outputs. We demonstrate the success of the method for a complex industrial mold. The approach is applicable to any complex mold geometry and any plastic.