bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some comments on the wear and friction behavior of fiber‐reinforced thermoplastics
Authors: Lhymn C. , Pulsifer A. H. 
Published: April 2003

AbstractThe frictional and wear behavior of fiber‐reinforced thermoplastic matrix have been investigated by means of tribological data and microscopy. Particularly the effect of sliding velocity, fiber content, and wear mechanism on the wear rate and friction coefficient has been studied. The observed data have been correlated with the wear and friction equation to test the validity of recent models qualitatively. The microstructural sequence of adhesive wear has also been investigated by means of the scanning electron microscopy. The effect of sliding velocity on wear rate is considered theoretically.
The effect of solids conveyance on the stability of the single screw extrusion process
Authors: Bigg D. M. 
Published: April 2003

AbstractThe flow of a polymer powder in the feed section of a single screw extruder has been experimentally investigated for its relationship to extruder stability. It is shown that the feeding and compaction process is inherently random, leading to random fluctuations in the position along the screw where melting begins. Such fluctuations are not considered serious under most circumstances, however. More severe fluctuations are generated when the taper of the compression zone causes the solid bed to re‐form across the screw channel. This disrupts the melting process, and prevents the extrusion process from proceeding in a steady state manner. Such a phenomena, is by its nature periodic, leading to long‐term fluctuations in the output of the extruder.
Study of extraction method on measuring insoluble constituents of ultrahigh molecular weight polyethylene
Authors: Eyerer P. , Kurth M. , Cui D. 
Published: April 2003

AbstractUltra‐high molecular weight polyethylene (UHMWPE) has exceptional physical properties and outstanding abrasion resistance. Examinations1,2 show property changes of explanted joint prostheses during different implantation times. Because of the in vivo aging, the molecular weight decreases while the amount of soluble parts increases. By irradiation sterilization, the UHMWPE is crosslinked and degraded. To measure insoluble constituents of UGMWPE, a new improved extraction method is given. The extraction coefficient depended on the kind of extractor and solvent but had no dependence on the height of sample placed in the glass filter crucible. Using this method to determine insoluble constituents had significant advantages.
Processability of organometallic polymer precursors for nonoxide ceramic applications
Authors: Kalyon Dilhan M. , Kovenklioglu Suphan 
Published: April 2003

AbstractNonoxide ceramics can be obtained from the high temperature pyrolysis of organometallic polymer precursors. This study has focused on the processing behavior was investigated employing a Rheometrics mechanical spectrometer, RMS 800, and a PerkinElmer Model 4 differential scanning calorimeter. The effect of various environments including nitrogen and oxygen were also studied. The melt processing capability of polycarbosilane was found to be rather limited. Finally, a model which describes the pore formation process during pyrolysis has been proposed.
Membranes, an important polymer product for industrial process technology—new developments concerning their manufacture and uses
Authors: Rautenbach R. , Janisch I. , Ing. Dipl. 
Published: April 2003

AbstractThe principles common to three membrane processes, i.e., reverse osmosis, and gas permeation, and pervaporation, involving separating by means of “dense,” i.e., pore‐free, synthetic polymer membranes are presented. On the basis of these principles, it is then shown how the requirements placed on the membrane and the modules by the transport mechanism (solution and diffusion) are satisfied. A few examples characteristic of the current state of technology are discussed.
Flow visualization of blending of elastomers and thermoplastics in an internal mixer
Authors: Min Kyonsuku 
Published: April 2003

AbstractFlow visualization of blending elastomers and plastics in an internal mixer is described. This is based on observations from front and transverse glass windows placed on the mixer. This enabled us to investigate the flow behavior of pure polymers during the blending operation. The flow behavior was categorized into four regimes which depend on temperature and the polymer. The flow regimes dominate the phase morphology of blends of ethylene–propylene terpolymer and polystyrene. Various rotor designs used in this study creates different two phase morphology due to various flow fields.
Effects of compounding techniques on the properties of mica‐reinforced engineering thermoplastics
Authors: Wright A. N. , Hawley G. C. 
Published: April 2003

AbstractPhysical properties of injection molded, mass‐granulated composites of poly(buteneterephthalate), modified PPO, and poly carbonate/PBT blends, reinforced with 30% by weight of Suzorite mica 60S were evaluated after compounding in the K‐mixer and in a single‐screw Killion extruder under a range of processing conditions. The properties varied considerably with the specific mixing conditions in both compounding systems. The K‐mixer gave higher un‐notched impact strengths for all conditions of processing for all three composites. The Killion extruder tended to give higher notched impact strengths. Tensile and flexural property development was more dependent on the plastic matrix. A wide spectra of property profiles could be developed in the K‐mixer simply by varying tip speed and discharge temperature whereas the exauder requhd changes in screw design. Current failure to produce suitable test bars from bisphenol A polycarbonate may be due to a requirement to predry the mica before mixing.
Damage accumulation and wear of fibrous composites
Authors: Lhymn C. 
Published: April 2003

AbstractA microscopic equation of wear rate has been constructed based on the physics of damage accumulation during sliding wear. The equation incorporates the effect of roughness as well as other structural and tribological parameters. Various factors affecting the wear rate have been identified. The experimental data of roughness vs. wear rate have been shown to support the proposed analysis under certain assumptions.
Polymer flow through spiral mandrel dies: A comparison of models
Authors: Perdikoulias J. , Vlcek J. , Vlachopoulos J. 
Published: April 2003

AbstractThree existing models used to simulate the flow of polymer melts through spiral mandrel dies are compared. Each model was of different complexity and provided different results when used to simulate the flow through two dies. All three models indicated an improvement in flow distribution when the power‐law index was increased. Experimental verification of the predictions is required before their validity is proven.
Effect of strength degradation on wear and friction
Authors: Lhymn C. 
Published: April 2003

AbstractA theoretical expression for wear rate as a function of sliding velocity has been formulated from the concepts of crack propagation, thermal activation, and strength degradation and the analytic results have been tested against the experimental data to provide a comprehensive understanding of this complex behavior. A similar equation describing the relationship between the wear rate and normal load has also been provided. The coefficient of friction has been analyzed theoretically as a function of normal load and sliding velocity and compared with the experimental results. The coefficient of adhesion has given an expression by employing two approaches: average crack propagation velocity and atomic residence time concepts. Consideration of strength degradation has led to a wear rate equation which does explain the experimental result satisfactorily for polymer composites. Some thoughts has been given to the atomic chain orientation effect on wear and friction, and also the boundary lubrication phenomena have been described briefly.
Friction and wear of fiber reinforced pps composites
Authors: Lhymn C. , Bozolla J. 
Published: April 2003

AbstractThe friction and wear properties of fiber‐reinforced polyphenylene sulfide composites were investigated under abrasive and adhesive wear conditions, and an attempt was made to explain the observed data with the friction and wear equations. The measured tribological data were also correlated with the observed microstructures.
The melting of granular polymeric solids on a hot moving surface—the effect of convection
Authors: Sun Tzu‐Hsiung 
Published: April 2003

AbstractThe effect of convection on the melting rate of granular polymeric solids pushed against a hot moving surface was analyzed by including in the energy equation the convection term to compute the melting film thickness. The results of this analysis indicate that the melting film thickness is reduced by the effect of convection, providing a theoretical basis for Tadmor's suggestion to reduce melting film thickness to account for the effect of convection in calculating the melting rate.
Instrumentation development for sensing modes of bubble motion of a blown‐film process
Authors: Huang T. A. 
Published: April 2003

AbstractWe have developed instrumentation using an internal‐bubble pressure transducer with a data acquisition system to sense LLDPE bubble stability on a commercial blown‐film line. Real‐time bubble instability was also recorded using a video camera at a speed of 30 frames/s. The pressure signal was analyzed using a fast‐Fourier‐transform (FFT) computer program to determine the frequency of bubble oscillation. Since bubble instability often consists of large‐scale oscillation and bubble flutter, and both motions affect gauge and layflat uniformity, the pressure signal was decomposed to determine the frequency of each oscillation mode. To obtain a stable bubble, the amplitudes of both oscillation modes must be reduced to a minimum. Under a single mode oscillation, the period of bubble‐diameter variation analyzed using videotape matches that of the pressure trace. The initial results indicated that the trace of the pressure can provide a warning to the stability of a blown‐film process.
Thermoforming crystallizing poly(ethylene terephthalate) (CPET)
Authors: Throne James L. 
Published: April 2003

AbstractNonisothermal crystallizing kinetics for nucleated polyethylene terephthalate (PET) are combined with transient heat transfer models to predict crystalline levels throughout the process of extruding and thermoforming crystallizing PET (CPET). The analysis includes:

PET molecular weight effect (through IV)
Nucleant level effect
Cooling of extruded sheet on chill rolls
Convection in the thermoforming oven
Oven radiant heater temperature
Radiation interchange efficiency in the heating oven
Equilibration
Mold surface temperature and atmosphere
Cooling time

The analysis compares distributed parameter finite difference analysis with a lumped parameter method. Material‐environmental parametric studies are conducted using the lumped parameter method. The patent literature data are confirmed using an expanded version of the lumped parameter method.
Development of experimental techniques and simulation methods to analyze mixing in co‐rotating twin screw extrusion
Authors: Kalyon Dilhan M. , Gotsis Alexandros D. , Yilmazer Ulku , Gogos Costas G. , Sangani Harish , Aral Birnur , Tsenoglou Christos 
Published: April 2003

AbstractCurrently, the selection of elements and operating conditions in the mixing of various materials in a corotating twin screw extruder is an art which requires previous experimental studies. In this report, we outline various experimental and theoretical tools developed to investigate the mixing process in a fully intermeshing corotating twin screw extruder. The thermomechanical history of mixing is simulated employing the finite element method. To verify the numerical findings, experimental techniques were developed to investigate the goodness of mixing of samples collected from a 50.8 mm, “clam shell” design, Baker‐Perkins twin screw extruder.
Computer‐aided plastic parts design for injection molding
Authors: Menges G. , Michaeli W. , Baur E. , Lessenich V. , Schwenzer C. 
Published: April 2003

AbstractA new software concept for an integrated computer‐aided design procedure for injection‐molded parts is presented. This software has been developed in close cooperation with the plastics industry and therefore takes into consideration, to a very high degree, requirements arising from practical use. The resulting program, named CADFORM, links commercial and newly developed plastics‐specific software and thus enables all the steps involved in designing a new molding and the corresponding mold to be carried out within one program system.
A computerized system for measurement of transient and equilibrium extrudate swell
Authors: Kamal M. R. , Samara M. 
Published: April 2003

AbstractA computerized automatic die swell apparatus has been designed and constructed. The apparatus provides both digital and analog outputs regarding the diameter of the molten extrudate and its variation with time. Precautions are made to reduce the effects of gravitational sag and temperature changes. The apparatus was used in conjunction with an Instron capillary rheometer to measure the transient and equilibrium extrudate swell behaviour of five low density polyethylene resins, a short fiber glass filled polypropylene melt, and a thermotropic liquid crystal polymer.
Flow visualization of internal mixer factory cycles for rubber compounding
Authors: Morikawa Akihiko , Min Kyonsuku , White James L. 
Published: April 2003

AbstractFlow visualization of a scaled down rubber compounding process in an internal mixer is described. The mastication of scaled down rubber bales, and the addition of carbon black and oil were studied. The times required for rubber bale ‘pickup’ by the rotors as well as bale homogenization time were determined for various elastomers. The times required to incorporate black and oil were measured.
Mixing characteristics of PC/PET polyblends in processing equipment
Authors: Awojulu Emmawuel A. , Deanin Rudolph D. , Huang Jan‐Chan 
Published: April 2003

AbstractUsing the melt blending procedure, various compositions of polycarbonate and poly(ethylene terephthalate) were compounded. Some of the blends were extruded and then injection‐molded, while others were directly injection‐molded into ASTM bars for physical testing. When the properties of these blends were compared, variations in values were obtained for blends of the same composition. Variations in properties were higher in blends containing less than 70% PET content. At 70% PET and above, there were negligible differences between blends of the same composition processed by different methods. Since it has been established that blends with more than 70% PET are miscible, it can be concluded that injection molding can be applied to mix miscible blends into final parts directly without a preliminary extrusion blending process.
Wear behaviour of silicone‐impregnated poly(ether etherketone)(PEEK) composites
Authors: Lhymn C. , Lhymn Y. O. 
Published: April 2003

AbstractThe wear and frictional behaviour of self‐lubricating polymer composites was investigates by means of tribological testing and microstructural examination. The tribological testing consists of wear rate measurement and frictional coefficient determination as a function of sliding velocity and normal load for two‐body abrasion and adhesive sliding tests. A new insight has been provided for the concept of “contact strenght” and related to the wear data using the appropriate wear equation developed from the crack propagation and damage accumulation physics.
Rheological properties, extrudate swell, and die entry extrusion flow marker experiments for rubber–carbon black compounds
Authors: Song Han Jong , White James L. , Min Kyonsuku , Nakajima Nobuyuki , Weissert Frederic C. 
Published: April 2003

AbstractRheological characterization, extrudate swell measurements, and a flow marker extrusion study for several elastomers and their compounds is reported. The materials included natural rubber (NR), styrene–butadiene rubber (SBR), ethylene–propylene terpolymer (EPDM), and polychloroprene (CR) and their carbon black compounds. The shear viscosity was measured with a sandwich rheometer, a shearing disk viscometer, and a capillary rheometer over a wide range of shear rates. Evidence for yield values is found in compounds with 0.20 and 0.30 levels of carbon black. Empirical equations were fit to the data. Extrudate swell measurements were carried out for slit and capillary dies. Increasing the level of carbon black reduces the level of swell. Flow marker experiments were carried out in the barrel of a capillary rheometer using a wide range of die designs. These indicated roughly radial streamline flows into the capillary or slit land. Recessed parts of a die could accumulate stagnant material. Evidence for wall slippage in the rheometer barrel for compounds with 0.20 and 0.30 volume fractions of carbon black is discussed.
On the wear of short carbon fiber reinforced carbon matrix composite
Authors: Lhymn C. , Lhymn Y. 
Published: April 2003

AbstractThe wear rate and friction coefficient of carbon–carbon composites have been investigated as a function of sliding velocity. Wear and friction models derived for fibrous polymer composites appear to be applicable for this carbon–carbon composite system. The microstructure of worn surfaces has been examined and correlated with the wear mechanism.
On the specific wear rate of polymer composites
Authors: Lhymn C. , Pepper S. V. 
Published: April 2003

AbstractA numerical calculation of specific wear rate has been attempted for two kinds of sliding wear (abrasive and adhesive) using a phenomenological equation derived from the concepts of crack propagation, delamination physics, and bond rupture. An approximate estimation of several parameters in the wear equation has been performed, and there appears to be and agreement between the theoretical and experimental wear rate within the order of magnitude.
A new model of flow in a tangential counter‐rotating twin screw extruder
Authors: Kim Myung H. , Szydlowski Witold , White James L. , Min Kyonsuku 
Published: April 2003

AbstractThe flow of Newtonian fluids in a tangential counter‐rotating twin screw extruder with matched and staggered screw flights is analyzed using hydrodynamic lubrication theory. The flow analysis network (FAN) method of Tadmor et al. as modified by Szydlowski et al. [Int. Polym. Proc., 1, 207 (1987)] has been applied to determine pressure fields and velocity fields. The results show lower pressure development and greater back flows for staggered flight as opposed to matched flight tangential counter‐rotating twin screw extruders. The predictions agree well with experimental studies. Earlier theories of Kaplan and Tadmor, and Nichols overpredict the performance of matched flight twin screw machines.
Three‐body abrasion of fibrous polymer composites
Authors: Lhymn C. , Sliney H. , Dellacorte C. 
Published: April 2003

AbstractThe three‐body abrasive wear behavior of Acetal/20 wt % carbon or glass fiber composites has been investigated as a function of sliding velocity and normal load. The observed data have been explained analytically by a new abrasion model developed from the concepts of crack propagation, energy balance, and Newtonian mechanics.
Dry erosion of epoxy/rubber composites
Authors: Lhymn C. , Lhymn Y. , Richardson D. E. 
Published: April 2003

AbstractThe dry erosion behavior of epoxy/waste rubber composites has been investigated as a function of rubber content, air pressure (particle velocity), and impact angle. Morphological aspects have also been examined. The experimental data have been explained by means of an analytic equation derived from the crack propagation physics.
Effects of moisture on thermal and mechanical properties of nylon‐6,6
Authors: Pai Chih‐Chiang , Jeng Ru‐Jong , Grossman Steven J. , Huang Jan‐Chan 
Published: April 2003

AbstractThis study examined the moisture absorption and other properties of nylon‐6,6 as a function of mold temperature and annealing effects. Moisture absorption was seen to decrease as the temperature of molding and annealing increased with a predictable effect on mechanical and thermal properties: namely, increased moisture absorption indicated lower strength, stiffness, but higher ductility and impact resistance. Thermal analysis by differential scanning calorimetry indicated that with an increase in moisture absorption in the nylon‐6,6 a broadening of the melting endotherm is observed, suggesting a typical plasticizing effect of water on the nylon‐6,6. This study suggests that molding conditions of a nylon‐6,6 material may ultimately effect the levels of crystallinity in the final part and establish a relationship between the amount of absorbed water for a given nylon product and its processing variables.
Pressure effect in capillary rheometer
Authors: Huang Jan‐Chan , Shen Hsiao‐Fu 
Published: April 2003

AbstractSteady shear viscosity data of a polypropylene resin were obtained at two elevated temperatures using an Instron capillary rheometer. When the pressure drop across the capillary is small, the hydrostatic pressure in the barrel is low, and the data from the capillary rheometer follow a linear Bagley plot. For long capillary and under a high hydrostatic pressure, the pressure drop increases at a faster rate than the length. A. pressure‐dependent viscosity function is proposed to explain the deviation and a new method to evaluate the pressure coefficient is introduced in this study. The results indicate that there is a significant increase in viscosity at a typical injection molding pressure, e.g., above 108 Pa.
Study of the compaction and sintering of two high‐performance thermoplastic polyimides
Authors: Throne James L. 
Published: April 2003

AbstractCompression and sintering studies on powders of two thermoplastic high‐performance polyimides—Amoco Torlon polyamide‐imide and Mitsui Toatsu LaRC TPI polyimide—show that the partially crystalline polyimide, LaRC TPI, exhibits substantial pressure‐dependent cold flow, below its traditional melting point. Torlon PAI, a completely amorphous polymer, exhibits a more traditional pressure‐dependent compaction density.
Recent advances in ABS/PC blends
Authors: Huang Jan‐Chan , Wang Ming‐Song 
Published: April 2003

AbstractABS/PC blending systems are triple phase mixtures of SAN copolymer, polycarbonate and polybutadiene rubber. In this paper, the solubility parameter approach is used to calculate the optimum volume fractions of acrylonitrile component in the continuous phase of ABS, at which the best solubility parameters of the blends of ABS with other polymers were obtained. To obtain the best result, one needs to separate solubility parameter into three components: dispersive δd, dipolar δp, and hydrogen bonding δh. The thermal, mechanical, and rheological, morphological characteristics and weathering as well as miscellaneous properties are reviewed.