bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of transient sorption and permeation in heterogeneous media
Authors: Kang Yong‐Soo , Meldon Jerry H. , Sung Nak‐Ho 
Published: December 2004

AbstractExperimental data on hexane vapor sorption in phase‐segregated polybutadiene/polystyrene blends are reported, which exhibit seemingly non‐Fickian characteristics that previous workers with styrene/butadiene copolymer attributed to a diffuse interphase. These data, plus results derived from a model of sorption in heterogeneous media containing a slowly permeable dispersed phase, indicate that the mere presence of two phases with different diffusion time constants is a sufficient condition for apparently non‐Fickian overall behavior. Consequently, definitive morphological inferences cannot be drawn from such observations. In addition, results of modeling the corresponding permeation process are analogous to those obtained in an earlier study of permeation with immobilizing chemical reaction.
Creep and recovery behavior of a linear high density polyethylene and an ethylene‐hexene copolymer in the region of small uniaxial deformations
Authors: Crissman J. M. 
Published: December 2004

AbstractThe results of creep and recovery experiments are reported for two types of polyethylene—one a linear high density homopolymer, and the other an ethylene‐hexene copolymer. Data were obtained at temperatures in the range 23°C to 57°C and creep times of 10 s to 4.33 × 105 s. In order to approximate constant true stress conditions, all of the experiments were carried out at the same value of applied stress (4 MPa) and the change in strain during creep was in all cases less than 2 percent. Comparison of these results with the results from earlier work on an ultra high molecular weight polyethylene shows that there is a great similarity in the behavior of all three materials, and the behavior of all three can be described quite well by a one‐dimensional equation consisting of two terms—one a hereditary term and the other a plasticity term. It is further shown that to a very good approximation the idea of time‐temperature superposition can be applied to the description of the hereditary term.
Temperature changes in poly(methyl methacrylate) and high‐density polyethylene during rapid compressive deformation
Authors: Rodriguez E. L. , Filisko F. E. 
Published: December 2004

AbstractThe adiabatic temperature changes for poly(methyl methacrylate) (PMMA) and high‐density polyethylene are reported as the result of rapid compressive stress applications at different temperatures. A specially‐modified Instron capillary rheometer was used in the experiments. Results were examined by determining the experimental thermoelastic coefficients (δT/δ). These were compared with the predicted coefficients from the equation (δT/δ) = ∝LTo/ρCp. Good agreement was found for ambient temperature, and deviations were found for higher temperatures. High‐density polyethylene showed higher temperature changes than PMMA, the causes for which are also discussed.
Integral sorption with induced crystallization
Authors: Durning C. J. , Rebenfeld L. , Russel W. B. 
Published: December 2004

AbstractWe studied the integral sorption of saturated, organic vapors in amorphous films of poly (ethylene terephthalate) (PET) using a spring balance apparatus. The penetrants employed (methylene chloride [MeCl2] and N. N. dimethyl formamide [DMF]) induce substantial crystallization of the polymer during sorption. The experimental data (mass of vapor absorbed versus exposure time) do not obey Fick's law for diffusion but reflect the influence of time dependent polymer swelling and crystallization. The data show that polymer swelling controls the penetrant transport in thin films, while molecular diffusion in the highly swollen semi‐crystalline polymer controls in thick films. Small activation energies were found for transport in thin films suggesting that ductile deformation controls the swelling in PET. A mathematical model developed previously explains the important features of the experiments.
A molded deep‐UV portable conformable masking system
Authors: Lin B. J. , Chao V. W. , Petrillo K. E. , Yang B. J. L. 
Published: December 2004

AbstractA second‐generation capped deep‐UV portable conformable masking system Is described. Two major improvements of this system are; (1) The replacement of the PMMA bottom layer with the PMMA‐MA‐MAN terpolymer which has a higher thermal stability and a higher deep‐UV sensitivity. (2) The application of the mold hardening process to eliminate the “wings” protruding from the novolac‐terpolymer interface, to facilitate a better choice of developers for the bottom layer, and to provide a better refractive index match between the novolac image lines.
Radiation‐induced reactions of ring‐substituted polystyrenes analyzed by radiolysis of low molecular‐weight model compounds
Authors: Tanigaki Katsumi , Tateishi Kazuo , Ohnishi Yoshitake 
Published: December 2004

AbstractRadiation‐induced reactions of polystyrene derivatives have been studied by the radiolysis of ring‐substituted isopropylbenzene derivatives, i. e., 4‐amino. 4‐hydroxy, 4‐methoxy, 4‐methyl, 4‐chloromethyl, 4‐chloro, and 4‐acetyl derivatives. Low‐temperature ESR analyses measured at 77 K indicate that. In general, the a‐position is the most sensitive site to radiation and that thus a‐radicals are produced through a‐hydrogen removal. However, among these derivatives, the amino, acetyl, chloromethyl, and. chloro derivatives undergo different reactions from the other derivatives. A phCOCH3 cleavage from the‐ acetyl derivative and NH cleavage from the amino derivative occur, and chlorine removal takes place from the chloro‐methyl and chloro derivatives. Final products detected by gas chromatography‐mass spectrometry indicate not only that radiation‐induced free radical recombination occurs. but also that if chlorine is produced by radiation, hydrogen abstraction by radiation‐induced chlorine takes place prior to the free radical recombination. The susceptibility of each derivative to hydrogen abstraction by radiation‐induced active chlorine increases, as the electron‐donation of ring‐substituents is increased. Based on the clarified reaction mechanism, the design of polystyrene derivatives as resist materials is discussed and two new types of resist systems are described. One is a new chloromethylstyrene based blend resist, which is formulated from poly(4‐meth‐oxystyrene) and poly(4‐chloromethylstyrene). The other is a new non‐swelling alkaline developable negative resist, which is formulated from poly(4‐hydroxystyrene) and a chlorine‐releasing compound.
Optimal developer selection for negative acting resists
Authors: Novembre A. E. , Masakowski L. M. , Hartney M. A. 
Published: December 2004

AbstractA methodology for determining the optimal single component developer/rinse pair for a negative acting resist is described. This method is applicable to any resist basing its negative action on crosslinking and development in organic based solvents. Within the method, initial developer/rinse candidates are identified by utilizing the Hansen 3‐dimensional solubility parameter model. This model provides a thermodynamic solubility picture of the resist, and determines those developers which will only minimally contribute towards swelling of defined features. Developer/rinse pairs are subsequently evaluated for acceptable resist dissolution kinetics, and compatibility with existing spray development processes. The optimum developer/rinse pair will only minimally effect changes in temperature which result in a minimum sensitivity to relative humidity variations. The use of this method is illustrated by choosing an optimal developer/rinse system for a chlorine containing, styrene based negative acting resist. The overall electron beam lithographic performance of this resist is shown to be improved with respect to a previously used 2‐component ketone based developer.
Phase decomposition phenomena in polystyrene/(polyvinylmethylether)
Authors: Han C. C. , Okada M. , Muroga Y. , Bauer B. J. , Tran‐Cong Q. 
Published: December 2004

AbstractThis paper reports studies on polystyrene/poly‐(vinylmethylether) blends to elucidate phase decomposition phenomena. Small angle neutron scattering (SANS) and temperature jump light scattering (TJLS) techniques were used to study both static and kinetic properties. The SANS methods were used to characterize the blends with respect to phase diagram, the Flory‐Huggins interaction parameter, and the critical fluctuation length as a function of temperature. From the TJLS experiments, we have demonstrated the possibility of two kinds of phase decomposition mechanisms which should lead to distinct morphology and material properties.
Fabrication of high modulus films by solid state rolling
Authors: Bigg D. M. , Smith E. G. , Epstein M. M. , Fiorentino R. J. 
Published: December 2004

AbstractSolid state rolling of semicrystalline polymers represents a high speed process for producing oriented, high modulus films, tapes, and sheets. The important process variables include roll temperature, thickness of initial sheet, roll speed, take‐up tension, roll diameter, and initial morphological state of the polymer. Roll temperature controls both the extent of maximum deformation and the rate of rolling. A minimum temperature exists for each polymer below which the orientation process is sharply limited. This condition is similar to the limitation present in the hydrostatic extrusion process, in which the alpha crystallization temperature limits the orientation process. Roll speeds as high as 20 m/min have been realized. It is apparent that film thickness and thickness reduction ratio have a strong effect on the ultimate rolling rate. The process, as currently practiced, is adiabatic, and therefore, heat transfer limited. The take‐up tension influences the extant of orientation in the amorphous phse of of the polymer. This in turn affects its thermal and chemical stability. The effect of roll diameter is to limit the extent of thickness reduction by causing roll‐film slippage when the roll dianmeter to thickness reduction ratio is below some as yet undetermined value. The initial morphological state of the polymer affects the amount of crystalline deformation possible, the surface texture of the rolled film, and the tear resistant of the oriented film.
Molecular orientation of polydimethylsiloxane induced by elongational and shearing strains
Authors: Santerre J. P. , Picot J. J. C. 
Published: December 2004

AbstractA study examining the molecular orientation of poly(dimethylsiloxane) for different combinations of elongational and shear strains is presented. Three different cases were studied: (1) pure elongational strain; (2) increasing shear and decreasing elongational strains; (3) increasing shear and increasing elongational strains. The experiments were performed in a converging flow cell (at room temperature), where elongational and shearing strain rates achieved values of 370 s−1 and 640 s−1 respectively. Values of the Hermans orientation function were obtained from measurements of birefringence and polarization angles while strain rates were estimated from laser Doppler anemometry velocity measurements. Prospects for predicting molecular orientation from the stress‐optical laws and rheological flow models are outlined and commented on.
The dynamic properties of glass‐fiber‐reinforced polypropylene subjected to pure bending
Authors: Worth R. A. 
Published: December 2004

AbstractThe dynamic tensile properties of glass‐fiber‐reinforced polypropylene have been measured for pure bending. The specimens were cut from the injection molded outer drum of a washing machine. Fiber orientation within the specimens was investigated using a scanning electron microscope, and was observed to be predominantly in the direction of flow, throughout the thickness of the material. It was found that the stiffness was greater in the direction of fiber orientation, while the damping was greater in the transverse direction. The results were in general agreement with values obtained from torsion pendulum experiments.
Characterization of stress relaxation curves of plastic foams
Authors: Miltz Joseph , Ramon Ori 
Published: December 2004

AbstractStress relaxation curves of plastic foams can be normalized and presented as a linear function of time. The two parameters derived from this model provide information about the residual modulus and relaxation rate. This simple method was found to describe relaxation curve as well as the more complex successive residuals method. It was found that the residual relaxation modulus as determined by the normalization and linearization technique depends on the strain history of the samples.
Glass transition relations in ionomeric “comb” polymers
Authors: Wollmann D. , Gauthier S. , Eisenberg A. 
Published: December 2004

AbstractThe glass transition temperatures (Tg) and dynamic mechanical properties of random copolymers of styrene‐4‐vinylpyridine quaternized with iodoalkanes are presented for vinylpyridine contents up to ten percent and pendant alkyl chains up to ten carbons in length. Two linear relationships, between ion content and glass transition temperature and between pendant alkyl chain length and theTg, are observed. An equation is presented that can be used to predict theTgfor such copolymers based on their ion contents and alkyl chain lengths.
Dielectric behavior of carbon black filled polymer composites
Authors: Yacubowicz J. , Narkis M. 
Published: December 2004

AbstractThis paper reports results on the dielectric properties of carbon black filled crosslinked polyethylene composites. These systems are shown to follow percolative type models. The dielectric constant increases slowly, with carbon black concentration, up to roughly the percolation concentration and then increases rapidly over the whole concentration ranges studied. The dissipation factor‐concentration curves are bell‐shaped with maximum values at approximately the percolation concentration. The dielectric properties of these systems are discussed in terms of interfacial Maxwell‐Wagner polarization effects.
Predicting large strain deformation of polymers
Authors: Nimmer Ronald P. 
Published: December 2004

AbstractAlthough yield stress and its dependence upon temperature and strain rate are well characterized for many thermoplastics, there are a number of scientific and engineering situations that require additional information regarding post‐yield deformation behavior. For example, the prediction of formability in plastics will require a quantitative description of constitutive behavior for strains between 40 and 300 percent, depending on the plastic. Data characterizing this behavior now exists for a number of plastics, and an analytical understanding of its effect on mechanical behavior has also been established. The purpose of this investigation is to apply the experimentally measured large‐strain constitutive behavior of polycarbonate to the analysis of several simple forming experiments and illustrate the accuracy of current predictions in comparison to experiment. Analyses of a tensile test, a “bend‐stretch” forming experiment, and the indentation of a circular disc by a hemispherical punch are compared with experiments. Agreement between analysis and experiment is very good for all geometries considered.
Fracture and toughness of crystalline polymer solids
Authors: Narisawa Ikuo 
Published: December 2004

AbstractThe development of plastic deformation and crazing in the neighborhood of a notch has been studied in connection with nonlinear fracture processes of crystalline ductile polymers, polyethylene, polypropylene, and propylene‐ethylene block copolymers. After revealing the morphology of plastic deformation around the notch and studying the effects of crystalline structure on ductile fracture processes, the J‐energy analysis was applied to give a criterion for crack initiation in the fracture of these elastic‐plastic materials. The material resistance to stable and unstable cracking was characterized using the curves of J against crack extension Δα.
Shear and craze competition in subcritical fatigue crack growth: Fatigue lifetime inversions
Authors: Takemori Michael T. 
Published: December 2004

AbstractIn some ductile amorphous polymers, the fatigue lifetime behavior can exhibit two distinct crack propagation modes: a craze dominated sub‐critical discontinuous crack growth mode, which leads to a low stress, short fatigue lifetime branch and a shear fracture mode, which produces a higher stress, long lifetime branch. When both branches coexist, the fatigue lifetimes at higher stress amplitudes are often longer than those at lower stress amplitudes! This unusual lifetime inversion has been explored for a polyestercarbonate at various temperatures, frequencies, degrees of physical aging, and fatigue overload histories.
Fracture of adhesive joints and laminated composites
Authors: Lee Shaw Ming 
Published: December 2004

AbstractThe mechanisms of resin controlled failure in adhesive joints and composites (delamination and transverse cracking) are examined. An in‐situ failure model based on the fracture mechanics principles is applied here to describe the failure processes involved. The model centers on the crack tip plastic zone developed in the thin resin layer between the fibers or the adherends. The plastic zone in the resin layer is heavily influenced by a dominant slow varying stress distribution, approximated to be r−m/2 dependent with m ≪ 1 (r is the distance from the crack tip). The adhesive or composite fracture toughness G*IC can then be expressed as a function of several resin properties of comparable importance: modulus E, yield stress σy, resin GIC and residual stress. The relative significance of the resin properties on the adhesive or composite fracture is discussed. The effects of temperature, loading rate, and resin toughening on such failure as a result of the corresponding variations in resin properties are also addressed.
High‐Temperature large‐strain behavior of polycarbonate, polyetherimide and poly(butylene terephthalate)
Authors: Nied H. F. , Stokes V. K. , Ysseldyke D. A. 
Published: December 2004

AbstractA noncontacting experimental procedure has been used for characterizing the high‐temperature large‐strain uniaxial behavior of polycarbonate (PC), polyetherimide (PEI), and poly(butylene terephthalate) (PBT), through controlled tests on flat specimens cut from extruded sheet. While each of these polymers exhibits stable necking over a broad temperature range, the transition to the necked state is shown to be more gradual at higher temperatures, resulting in a less sharply defined neck transition region during the drawing process. These trends in necking behavior, and other phenomena such as double necking, which only occur at high temperatures, are illustrated through contour plots of the Cauchy‐Green deformation tensor. Elevated temperature true‐stress versus stretch data are given for each of these polymers.
Nonlinear response and thermomechanochemical degradation of a urethane elastomer
Authors: Mead Joey , Singh Sachchida , Roylance David , Patt Jacob 
Published: December 2004

AbstractWe have studied the failure of a urethane elastomer due to cyclic compressive loading, using loading frequencies and specimen sizes for which internal heat generation is an important factor. The eventual failures were generally manifest by internal cracks growing transverse to the loading direction. A variety of experimental analyses indicate that this failure is primarily thermal, in that the temperature rise due to viscous dissipation eventually leads to a melting of the hard segment domains which act to reinforce the material. No strong indication of thermal or thermomechanical bond scission was obtained, although a progressive reduction in the rubbery modulus was noted.
The torque in the metering zone of single screw extruders
Authors: Mennig G. 
Published: December 2004

AbstractTo study the energy dissipation in the different zones of an extruder, a special barrel has been designed where local torques Tq can be measured at the beginning of the conveying, the transition, and the metering zone. Experiments carried out for a commercial polyethylene and poly(vinyl chloride) at different processing conditions show that in some cases negative Tq in the metering zone may occur. A very basic analytical treatment of the flow situation in the metering zone shows that for a given drag flow Tq is dependent on the pressure gradient and particularly on its sign. Tq decreases with decreasing positive pressure gradient until there is pure drag flow. It further decreases with increasing negative pressure gradient until it becomes zero and even negative. A comparison of theoretical and experimental results for the metering zone shows good quantitative agreement though the main aim of the paper is to provide a better general understanding of the complex situations inside an extruder.
Thermal and cure analysis in sheet molding compound compression molds
Authors: Castro J. M. , Lee C. C. 
Published: December 2004

AbstractSheet molding compound (SMC) compression molding growth will benefit from faster cycles and more uniform cure so as to reduce in‐plane thermal residual stress and resulting warpage in the molded part. These improvements require an in‐depth study of the mold thermal design. Here we use a finite element model to analyze the quasi‐steady temperature distribution in a plane perpendicular to the heating channels of a representative mold, and a finite difference model to investigate the cure dynamics at critical regions. Several changes in the mold heating system and operating conditions were considered and their effects on the temperature distribution and cure time were studied. It was assumed that the steam condensate is well drained and enough steam is supplied so that the steam tube walls are kept at a constant temperature. An important conclusion of the present study is that better insulation of the mold from the press does not help much in improving the uniformity of cavity surface temperature or cure. It was also found that reducing the distance between two consecutive steam tubes beyond the distance from the steam tube to cavity surface will not yield a significant change. The most practical way to give both more uniform cavity surface temperature and faster cure is to have higher steam temperature for the region where the charge is initially placed.
An analytic study of tensile and puncture test behavior as a function of large‐strain properties
Authors: Nimmer Ronald P. 
Published: December 2004

AbstractThe mechanics of “cold‐drawing” in ductile thermoplastics are examined analytically. The fundamental postyield, strain hardening behavior of these thermoplastics as defined by a true stress versus true (natural) strain relationship is related to macroscopic, large deformation behavior in unidirectional tension tests arid axisymmetric puncture tests. The phenomena of load‐drop after yield and propagating necks are examined with respect to tension tests and are related to draw strain and large deformation strain hardening modulus. In addition, these same fundamental material properties are also shown to have a significant effect upon the energy absorption capability of thermoplastics as measured by puncture tests.
Unnotched impact bend test assessment of the degree of gelation in unplasticized poly(vinyl chloride) pipe
Authors: Kim H.‐S. , Cotterell B. , Mai Y.‐W. 
Published: December 2004

AbstractIt is suggested that the unnotched impact test is suitable for quantitative quality control of unplasticized poly(vinyl chloride) pipe. The relative level of processing is assessed by the probability that failure is nucleated at a surface flaw. Tests show that this assessment is very sensitive to the level of processing.