bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymer melt elongation—methods, results, and recent developments
Authors: Meissner Joachim 
Published: December 2004

AbstractFor film blowing of polyethylene it has been shown previously that melt elongation is very powerful for polymer characterization. With two types of rheometers, simple (also called “uniaxial”) elongational tests as well as creep tests can be performed homogeneously. In simple elongation, the melts of branched polyethylene show a remarkable strain hardening. With respect to their advantages and disadvantages, these rheometers complement each other. For multiaxial elongations the various modes of deformation can be performed by means of the rotary clamp technique. With the strain rate components ordered such that \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \varepsilon $\end{document}11 ⩾ \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \varepsilon $\end{document}22 ≥ \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \varepsilon $\end{document}33, the ratio m = \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \varepsilon $\end{document}22/\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \varepsilon $\end{document}11 characterizes the test mode. The Stephenson definition of the elongational viscosities makes use of the linear viscoelastic material equation and proves to be very efficient because the linear shear viscosity (t) (“stressing” viscosity) can act as the reference for the nonlinear behavior in elongation. Results are given for polyisobutylene measured not only in simple, equibiaxial, and planar elongations, but also in new test modes with a change of m during the deformation. This allows one to investigate the consequences of a deformation‐induced anisotropy of the rheological behavior.
Measurement of the viscosity of guar gum solutions to 50,000 s−1 using a parallel plate rheometer
Authors: Kramer Jeffrey , Uhl Jonathan T. , Prud'Homme Robert K. 
Published: December 2004

AbstractIt is frequently necessary to measure the viscosity of polymer solutions at high shear rates to obtain data under the conditions encountered in industrial processes. Such measurements are most often made on a capillary viscometer. This paper presents a method of determining solution viscosities at shear rates up to 50,000 s−1 in a rotational rheometer using a parallel plate geometry. The two keys to performing these measurements are very small gaps between the parallel plates (on the order of 50 microns) to eliminate inertial secondary flows, and the ability to increase and decrease the shear rate quickly to minimize viscous heating. A technique for setting and measuring small gaps is presented. Possible sources of error including inertia, axial compliance, and viscous heating are analyzed. A comparison Is made between the viscosity of a 0.7 percent hydroxypropyl guar (HPG) solution measured on the parallel plate rheometer and the viscosity measured in a capillary viscometer. Viscosities of HPG solutions having concentrations of 0.25, 0.50, 1.00, and 1.45 percent are presented over the shear rate range 100 to 50,000 s−1.
Properties of polycarbonate/acrylonitrile‐butadiene‐styrene blends
Authors: Chiang Wen‐Yen , Hwung Dao‐Shinn 
Published: December 2004

AbstractTo help make a good polymer blend by melt blending, the properties of polycarbonate (PC)/acrylonitrile‐butadiene‐styrene (ABS) systems with various compositions have been investigated. As ABS is blended into PC to form a binary system, Brabender torque is reduced, a phenomenon that results in Improved processability of PC. With increasing ABS content, the mechanical properties of the blends such as tensile strength, modulus, hardness, and shrinkage decrease. However, with the variation of composition, Izod impact strength shows a maximum, while elongation at break exhibits a minimum. These phenomena are discussed with dynamic viscoelasticities and scanning electron microscopic morphological results. The value of ΔTg(TgβPC − TgβABS) is at its smallest when the ratio of PC to ABS is 90:10, However, the value rises with an increase in ABS because the butadiene content of the ABS hinders compatibility in the binary system. At the 90:10 composition, the damping height is optimal. In addition, the dispersed phase of the ABS is most ideal, absorbing the impact force and showing high impact strength. Composition ratios other than 90:10 present high damping as well as undesirable phase separation because of poor adhesion between two phases. As a result, the mechanical properties are reduced.
Mechanical and flow properties of high‐density polyethylene/low‐density polyethylene blends
Authors: Garcia‐Rejon Andres , Alvarez C. 
Published: December 2004

AbstractThe recycling of plastic waste is of particular interest in large urban areas where municipal waste represents a large ecological problem. To achieve their objective (consumer products from plastic waste), formulators of a recycling program have to understand the implications of working with mixtures of different resins. Furthermore, in a multiphase system, the thermomechanical history experienced by the resins during processing represents an important link between operating conditions, resin properties, and final product performance. High‐density polyethylene/low‐density polyethylene (HDPE/LDPE) blends (10, 20, 35, 50, 65, 80, and 90 percent by weight HDPE) were melt blended in an internal mixer. A complete rheological characterization was performed on each blend. The resulting blends were extruded under different processing conditions. The extruded sheets were further characterized to determine their mechanical properties, The experimental results show important differences in the mechanical properties (transverse and longitudinal) of the sheets obtained from the blends. These differences are explained on the basis of the processing conditions (thermomechanical history) and the rheological properties of the molten blends.
Laminar morphology in polymer blends: Structure and properties
Authors: Subramanian P. M. , Mehra V. 
Published: December 2004

AbstractPolymer‐polymer blends offer a route for enhancement of various properties. When immiscible polymers are blended together (in the presence of a compatibilizer), the blend properties are dependent on the morphology of the phases. Uniform, fine dispersions generally result in “average” properties. Discussed here are blends of polyamides or polyesters with polyolefins, particularly polyethylene, where small amounts (3–20 percent) of the former polymers dispersed as essentially parallel, thin, large laminae produce substantial reduction (3–100 times) of permeability properties in blow‐molded/extruded articles. Physical properties of such blends, their permeability properties, and morphologies are discussed.
Polymer sorbents for phosphorus esters: II. Hydrogen bond driven sorption in fluoro‐carbinol substituted polystyrene
Authors: Barlow J. W. , Cassidy P. E. , Lloyd D. R. , You C‐J. , Chang Y. , Wong P. C. , Noriyan J. 
Published: December 2004

AbstractA series of copolymers containing styrene and a fluorocarbinol substituted styrene, vinyl benzyl hexafluorodimethyl carbinol, were prepared by substitution of hexafluoroacetone on polystyrene followed by hydrolysis, and by copolymerization of styrene and substituted styrene monomers. Sorption of dimethyl methyl phosphonate, DMMP, vapor in the copolymers was examined at 135°C by the piezoelectric sorption method and at 135 to 165°C by Inverse Gas Chromatography, IGC, and the results were analyzed by the Flory‐Huggins equation. Both methods yield similar negative values of the Flory‐Huggins Chi parameter at 135°C, and the Chi values are observed to become increasingly negative to −4.9 as the percent substitution of the aromatic rings In the copolymer is increased to 54 mole percent. A simplified thermodynamic analysis, based on experimental studies of the hydrogen bond formed between DMMP and hexafluoro‐isopropanol, an analog of the fluoro‐carbinol, through infrared spectroscopy and calorimetry at ambient conditions, is shown to predict the Chi dependency on copolymer composition observed at 135°C to within the accuracy of the experimental observations, however, the analysis predicts a decrease in Chi with increasing temperature that is too high relative to values observed by IGC at temperatures greater than 135°C.
Effect of segmental diffusion on irreversible, step growth polymerizations of ARB monomers
Authors: Kumar Anil , Saksena Kamal , Foryt John P. , Gupta Santosh K. 
Published: December 2004

AbstractThe role of segmental diffusion in step‐growth polymerizations has been studied using a simple, phenomenological theory. Theoretical results have been generated to study the effect of the parameters, several of which can be estimated from experiments on non‐reacting systems. The values of the parameters have been selected in this study in such a manner that segmental‐diffusional limitations are encountered quite early during polymerization. This facilitates detailed parametric sensitivity studies. Thereafter, the model is used to predict behavior of trains of reactors, and more appropriate values are used for the parameters. Segmental‐diffusional limitations are then limited to final stages of polymerization (as indeed they are in industrial practice).
The calorimetric and mechanical properties of virgin and recycled poly(ethylene terephthalate) from beverage bottles
Authors: Müller A. J. , Feijoo J. L. , Alvarez M. E. , Febles A. C. 
Published: December 2004

AbstractIn the present work, fusion behavior, crystallinity, and mechanical properties of beverage bottle poly(ethylene terephthalate) (PET) was compared with those of the virgin material. Viscosimetry measurements, differential scanning calorimetric studies, impact and tensile determinations were made in both materials. The lower Mv of bottle PET revealed that a thermomechanical degradation occurred during processing. Although bottles possess a considerable degree of crystallinity (≈30 percent), the crystallites are so small that they don't scatter light and, therefore, bottles are transparent. Virgin PET exhibited a brittle behavior while bottle PET exhibited a ductile one. This is a consequence of the difference In crystallinity between both materials (greater for virgin PET because of its original higher crystallinity content), although they were molded under the same conditions. Such difference was attributable to a “crystalline memory” effect having its origin in the orientation of the material during Injection molding at low temperature (250°C). Injection‐molded PET specimens showed a strong, crystalline memory, capable of crystallization during very fast quenchings.
Determining viscosity temperature behavior of four amorphous thermoplastics using a parallel plate technique
Authors: Macho E. , Alegría A. , Colmenero J. 
Published: December 2004

AbstractThe temperature dependence of the Newtonian viscosity, ηo(T), of four structurally related amorphous thermoplastics (polyarylate, polysulfone, polycarbonate, and phenoxy) was measured in the temperature region between Tg and (Tg + 100 K) by means of a parallel plate technique. This offers a simple and quick alternate mode of measurement to traditional techniques. Values of ηo(T) measured, as well as some data obtained from literature and corresponding to the T > (Tg + 100 K) range, were fitted to Vogel‐Fulcher expressions. Fractional free volume at Tg was evaluated from Vogel‐Fulcher parameters. The values obtained are similar for all polymers studied, and they are greater than those normally observed for other amorphous polymeric systems that are structurally simpler. From the results obtained we can conclude that the rheological behavior and, hence, the chain “stiffness” of polyarylate, polysulfone, and polycarbonate, at the temperature range of industrial processing, are very similar. However, phenoxy, which contains a greater number of nonaromatic flexible structures in its chain, has a different behavior with a lower activation energy for viscous flow in the same range of temperature.
Measurement and correlation of mutual diffusion coefficients for molten polystyrene‐hydrocarbon systems
Authors: Iwai Yoshio , Kohno Masafiide , Akiyama Takayuki , Arai Yasuhiko 
Published: December 2004

AbstractThe mutual diffusion coefficients for three molten polystyrene(PS)‐hydrocarbon systems—PS‐in‐xylene, PS‐n‐octane, and PS‐n‐nonane—were measured by using a sorption apparatus with quartz spring in the temperature region from 130 to 175°C and for mass fraction of hydrocarbon ranging from 0 to 0.15. The mutual diffusion coefficients were correlated with good agreement by the freevolume theory.
A miscible nylon blend with poly(2‐vinyl pyridine)
Authors: Skrovanek Daniel J. , Coleman Michael M. 
Published: December 2004

AbstractPolymer blends of an amorphous polyamide with poly(2vinyl pyridine) (P2VP) are presented. Differential scanning calorimetry results suggest that the system exists as a single phase material as evidenced by a single glass transition temperature. However, as illustrated by light scattering studies, this miscible binary mixture possesses a relatively low, lower critical solution temperature (LCST). Fourier transform infrared (FTIR) spectroscopic investigations indicate that the interactions occur in the blend between the NH group of the polyamide and the N: atom of P2VP and that the strength of the Interactions between the components is nearly identical to that occurring in the self‐association of the pure amorphous polyamide. Additionally, by monitoring the concentration of “free” carbonyl groups, a quantitative measure of the number of interactions occurring in the blend is obtained.
Biaxial orientation of polypropylene by hydrostatic solid state extrusion. Part II: Morphology and properties
Authors: Pan S. J. , Tang H. I. , Hiltner A. , Baer E. 
Published: December 2004

AbstractChanges in the lamellar structure of polypropylene during biaxial orientation by hydrostatic extrusion have been examined. Examination of etched surfaces in the transmission electron microscope has revealed that up to a draw ratio of about 1.5 × 1.5 the primary mechanism is lamellar rotation into the plane of orientation, At higher draw ratios breakup of the lamellae is observed with formation of a granular structure. Thermal measurements suggest that localized melting and recrystallization may accompany the process of lamellar breakup. These morphological observations confirm the previous interpretation of SAXS and permit a more detailed model of the hierarchical structure to be proposed. Stress strain measurements show a gradual change from sharp necking to uniform deformation as the draw ratio is increased. On the other hand, the structural change at a draw ratio of about 1.5 × 1.5 Is accompanied by a large increase in the tensile impact strength.
Loss of 2‐tertiary‐butyl‐4‐methoxy phenol (BHA) from high‐density polyethylene film
Authors: Han J. K. , Miltz J. , Harte B. R. , Giacin J. R. , Gray J. I. 
Published: December 2004

AbstractThe rate of loss of the antioxidant 2‐tertiary‐butyl‐4‐methoxy phenol (BHA) from high‐density polyethylene (HDPE) was determined using high pressure liquid chromatography (HPLC). The rate of loss was found to follow a first‐order expression. Almost all of the antioxidant was lost (>95 percent) within 1 day at 50°C, within 3 days at 40°C, and within 7 days at 30°C. The controlling parameter for mass transfer of the antioxidant was found to be volatilization rather than diffusion.
Surface spectroscopic studies of poly(methyl methacrylate) (PMMA) and modified PMMA surfaces
Authors: Salvati Lawrence , Hook Thomas J. , Gardella Joseph A. , Chin Roland L. 
Published: December 2004

AbstractMultitechnique surface characterization of plasma and chemically modified poly(methyl methacrylate) (PMMA) is reported using Low Energy Ion Scattering Spectrometry (LEIS or ISS) and angular‐dependent X‐Ray Photoelectron Spectroscopy (XPS or ESCA). A complete picture of the depth, extent, and mechanism of modifications developed. ISS yields results, which especially complement ESCA because of the sensitivity to functional group arrangement due to shadowing and shielding of atoms in the topmost layer.
Shelf life of phenolic resole resins
Authors: Gupta Manoj K. , Hindersinn Raymond R. 
Published: December 2004

AbstractViscosity, number‐average and weight‐average molecular weights (measured by gel permeation chromatography), and carbon‐13 nuclear magnetic resonance (NMR) were used to monitor the changes in phenolic resoles as a function of time and pH. It was observed that phenolic resoles with pH around 5 are more stable, as indicated by the lowest increase in viscosity and molecular weight. Carbon‐13 NMR spectroscopic studies also suggest that the concentration of methylol groups is higher for resoles with pH around 5 and, thereby, indicate a slower reaction.
Elastic contact stress analysis of semi‐crystalline polymers under normal and tangential loading
Authors: Youn Jae R. , Su Ching‐Lo 
Published: December 2004

AbstractStress distribution in a polymeric subsurface under the asperity contact is investigated assuming the well known Hertzian contact stress distribution. Elastic stress analyses for three different materials are performed using a finite element method: (1) isotropic elastic solid, (2) isotropic elastic solid with a soft layer, and (3) isotropic elastic solid with a hard layer. Highly linear polymers as high density polyethylene (HDPE), poly(tetrafluoroethylene) (PTFE), and polyoxymethylene (POM) which transfer thin wear films are modeled as the elastic solid with a soft layer. Gammaray irradiated highly linear polymers and the other ordinary semi‐crystalline polymers which transfer massive lumpy wear debris are considered as the elastic solid without any heterogeneous surface layer. Helium plasma treated polymers are modeled as the elastic solid with a hard layer. Octahedral shear stress and equivalent strain contours in the subsurface are obtained for each case. The octahedral shear stress and equivalent strain distributions are examined to explain various wear behaviors of semicrystalline polymers based on the Mises yield criterion and the delamination theory of wear.
Influence of materials and structure on performance of a football helmet
Authors: Vetter L. , Vanderby R. , Broutman L. J. 
Published: December 2004

AbstractA nonlinear finite element model for the static analysis of football helmets is developed as a first step in a methodology for the mathematical modeling of helmets. Polycarbonate and acrylonitrile‐butadiene‐styrene are considered as the shell material for the helmet. Such a methodology can be used to predict helmet response to loading and impact and can be incorporated in a computer program studying injuries caused by helmeted head collisions in football. Numerical results in terms of force‐deflection curves, maximum stresses, and work of deformation are given. The influence of the polymeric material forming the helmet shell on energy absorption is studied. The effect of the internal padding material and suspension system is also considered.
Fracture toughness and crack instability in tough polymers under plane strain conditions
Authors: Lee L. H. , Mandell J. F. , McGarry F. J. 
Published: December 2004

AbstractThe plane strain fracture toughness and fracture mechanisms of several tough engineering plastics have been studied and compared with poly(methyl methacrylate) (PMMA), a relatively brittle polymer. The tough polymers all are observed to form a multiple craze zone at the crack tip, which is shown to be the primary source of plane strain fracture toughness in these materials. The multiple craze zone is retained during slow crack growth but is metastable, and at a critical stress intensity and associated crack velocity, the system passes through a transition to a greatly accelerated single craze mode of unstable propagation.
Modification of butadiene‐acrylonitrile rubber/poly(vinyl chloride) blend using natural rubber, styrene‐butadiene rubber, and polybutadiene rubber
Authors: George K. E. , Joseph Rani , Francis D. Joseph , Thomas K. T. 
Published: December 2004

AbstractNatural rubber, styrene‐butadiene rubber, and polybutadiene rubber were used to replace part of the butadiene‐acrylonitrile rubber in a 70/30 butadiene‐acrylonitrile rubber/poly(vinyl chloride) blend. Such replacement up to 15% of the total weight of the blend improved the mechanical properties, while decreasing the cost of the blend. Styrenebutadiene rubber could replace butadiene‐acrylonitrile rubber up to 30% of the total weight of the blend without deterioration in the mechanical properties.
Ductile tearing instability in some engineering thermoplastic blends
Authors: Dekkers M. E. J. , Hobbs S. Y. 
Published: December 2004

AbstractThe stability of ductile crack growth in two engineering thermoplastic blends is examined. The blends are a poly(phenylene oxide)/nylon 6,6 blend and a poly(butylene terephthalate)/polycarbonate blend. Fracture tests were performed with single‐edge notched specimens in tension and three‐point bending over a wide range of test speeds. Both larger radius notches and longer specimens were found to promote ductile tearing instability. This behavior is attributed to the higher driving force for crack growth produced by increased elastic energy storage before crack initiation. Over a certain range of test speeds, these factors lead to a novel effect of notch sharpness on toughness; a sharp notch gives rise to a higher fracture energy than does a blunt notch. The results are discussed in terms of the tearing modulus concept developed by Paris and co‐workers.
Space‐time distribution in filling a mold
Authors: Manas‐Zloczower I. , Blake J. W. , Macosko C. W. 
Published: December 2004

AbstractThe residence time of a fluid particle in mold filling is total time spent in the mold. Displaying curves of constant residence time in the mold gives the space‐time distribution during the filling process. A simple method to calculate space‐time distributions is presented. Applications to mold filling in reaction injection molding (RIM) are illustrated.
Adiabatic reactive viscometry for polyurethane reaction injection molding
Authors: Blake J. W. , Yang W. P. , Anderson R. D. , Macosko C. W. 
Published: December 2004

AbstractAdiabatic reactive rheometry involves the simultaneous measurement of viscosity and temperature changes during adiabatic polymerization. Using the adiabatic reactor method to relate temperature to fractional conversion results in a useful rheokinetic tool ideally suited for fastreacting reaction injection molding (RIM) systems for which the mold‐filling step is nearly adiabatic. In this work, a small laboratory RIM machine is used to mix the reactants and deliver them to a constant stress rheometer retrofitted with a wide‐gap Couette geometry and two thermocouples. Measurements on two polyurethane systems are reported. A simple cross‐linking system is used to verify the adiabatic rheokinetic method through comparison to a known gel conversion. Subsequent measurements on a phase‐separating RIM system show that increases in catalyst level, hard segment content, and initial reactant temperature result in a decreased gel time and an increased gel conversion. The viscosity rise profiles aid our understanding of the onset and development of phase separation. They are also essential for mold‐filling models and establishing moldability criteria for these RIM systems.