bluuebunny/crossref_metadata_2025_split huggingface dataset:
Notes on chlorinated polyethylene: Its preparation, some mechanical and thermal properties
Authors: Akovali G. , Vatansever A. 
Published: December 2004

AbstractLow density polyethylene was chlorinated via a mixed solution‐suspension technique at three different temperatures. The products obtained at different conditions had properties ranging from hard brittle to tough elastomeric consistencies. Static mechanical, chemical, and thermal characterization of the products were made and the possibility of two different crystal structures is pointed out, one of which is consumed preferentially during chlorination.
A computer interface for the fabrication and testing of surfactant films
Authors: O'Brien Kevin C. , Lando Jerome B. 
Published: December 2004

AbstractA computer interface was developed for a commercially available film balance to aid in the fabrication and characterization of surfactant films spread on water substrates. The interface is compatible with other commercially available systems, easily programmable, and able to perform a variety of tasks. This interface aided in following chemical reactions which occurred in the films, describing the morphology of the films, monitoring the process of film deposition, and also studying the mechanical properties of the films.
Thermal stability and compatibility of polyetheretherketone (PEEK) with an oxidizer and pyrotechnic blend
Authors: Moddeman W. E. , Bowling W. C. , Tibbitts E. E. , Whitaker R. B. 
Published: December 2004

AbstractPolyetheretherketone (PEEK) is a relatively new high temperature engineering thermoplastic. The stability of neat and fiberglass reinforced PEEK towards air, KClO4, and TiH1.65/KClO4 blend was studied by the surface sensitive technique of X‐ray photoelectron spectroscopy (XPS) and bulk technique of thermogravimetric (TG) analysis. Both of these examinations revealed no oxidation in the presence of air or KClO4 at temperatures of 60 or 120°C. In addition, no reduction of PEEK was observed in the presence of a reducing agent such as TiH1.65. The TG results also showed no air oxidation between 120 and 500°C.
Liquid sorption in a segmented polyurethane elastomer
Authors: Schneider N. S. , Illinger J. L. , Cleaves M. A. 
Published: December 2004

AbstractThe sorption and diffusion of a series of liquids in a segmented polyurethane have been studied to determine how the behavior is affected by the choice of solvent and the heterophase nature of the polymer. The polyurethane was composed of methylene‐di‐para‐phenylene isocyanate (MDI) butanediol, and poly(tetramethylene oxide) (1000) with a mole ratio 3:2:1. Immersion experiments in n‐heptane liquid, a poor solvent, and incremental sorption experiments in n‐heptane vapor showed normal Fickian havior. In the set of liquids of increasing polarity, which included 1‐chloroheptane, three dichloroalkanes and orthodichlorobenzene, the swelling increased to very high levels. Effective values of the molecular weight between crosslinks computed from the Flory Rhener equation, assuming complete phase segregation, varied widely with the different liquids. Agreement could be improved by allowing 30 percent mixing of hard segments with the soft segment phase. The sorption and desorption curves for the highly swelling liquids showed various anomalies some of which might be the result of solvent induced relaxation of hard segment domains.
The numerical simulation of boger fluids: A viscometric approximation approach
Authors: Mitsoulis E. 
Published: December 2004

AbstractA general‐purpose finite element program has been used to simulate the flow of nonshear‐thinning, highly elastic polymer solutions (Boger fluids). In particular, the creeping flow through an abrupt 4:1 circular and planar contraction is studied, as well as the flow at the exit of a capillary die for the determination of extrudate swell. Experimentally measured normal stress and viscosity data are included in a simple rheological model, based on the viscometric simplification of the CEF constitutive equation. Vortex size and intensity in the die entry and extrudate swell at the die exit increase rapidly, with elasticity level, in general agreement with experimental findings. It is shown that despite the limitations of the model, the viscometric approximation can be used to study the effect of normal stresses in cases where a main flow direction can unambiguously be defined. In die exit Flows, it can also provide an upper limit for the determination of extrudate swell, while Tanner's theory of elastic recovery provides the lower limit.
Monitoring the initial phase of a slow curing epoxy through the dynamic viscoelastic properties
Authors: Ganani Ehud , Higgins Brian G. , Powell Robert L. 
Published: December 2004

AbstractThe isothermal curing of an epoxy mixture of diglycidyl ether of bisphenol‐A and diglycidyl ether of 1,4 butanediol was monitored through the dynamic viscoelastic properties. Measurements were made at a frequency of 37.7 s−1 using a Weissenberg Rheogoniometer Model R‐17 fitted with a piezoelectric load cell and interfaced with a microcomputer. Cures were conducted at four temperatures, 15.6 ± 0.2°C to 40.1 ± 0.2°C with the cure time varying from 35 to 11 hours, respectively. Additional measurements of the steady shear viscosity, up to three hours after cure initiation, were conducted using a Weissenberg Rheogoniometer Model R20. These results show that in the early stages of the cure cycle, the fluids show low elasticity and constant viscosity. Also, independent of temperature, the relationship, η′ = 0.05 η″, holds, although it is not maintained near the gel point. This implies that initially, the longest relaxation time is independent of the extent of reaction and the temperature.
The viscoelastic and aging characteristics of polymers
Authors: Feng William W. 
Published: December 2004

AbstractThe time dependent mechanical properties for incompressible polymer‐like materials subjected to finite simple extension are studied. There are two parts: the viscoelastic effects and the aging characteristics. The constitutive equation developed by Christensen for finite deformation viscoelasticity is used. With two new material properties, the constitutive equation is extended to include the aging effects. An experiment is performed, and a method for determining these mechanical properties is presented in detail.
Biaxially stretched in comparison with conventionally blown coextruded composite plastic films
Authors: Siegmann A. , Nir Y. 
Published: December 2004

AbstractMultilayer composite films consisting of polyolefins, either polypropylene, linear low density or medium density polyethylene, a thin adhesive layer, and a polyamide in various ratios were prepared using two basically different processes. The first, a conventional blown film process in which the extrudate is stretched while in the molten state; and the second, a two‐stage process in which the quenched extrudate is stretched at a temperature below the polymers' melting point. The films so prepared, having identical composition and similar extents of stretching, were compared on the basis of their tensile properties, thermoelastic shrinkage, oxygen transmission rate, and thermal behavior. The effects of stretching temperature, rate, and extent on the behavior of the composite films and control single layer films were investigated. The stretching temperature was found to be the dominating single process parameter in determining the films' behavior. The overall performance including tensile properties, barrier, and shrink properties of the “cold” stretched films was found markedly superior to that of the conventionally blown films. The stretched composite films possess physical properties that cannot be attained by the conventional process.
Polyurethane elastomers containing polybutadiene and aliphatic diols: Polymerization and structure
Authors: Cohen D. , Siegmann A. , Narkis M. 
Published: December 2004

AbstractThe effect of aliphatic diols on the polymerization and network formation of polyurethane elastomers containing hydroxyl terminated polybutadiene and three different diisocyanates was studied. The polymerization/curing progress was followed by viscosity measurements, IR spectroscopy, swelling, extraction, and hardness measurements. The resulting networks were characterized by swelling experiments. The type of diisocyanate and the diol chain length were found to have significant effects on the reacting mixtures throughout the polymerization course. The effects observed included the phase structure of the reacting mixtures, the reaction rate, the crosslink density, and the physical interactions.
The simulation of phase diagrams for polymer blends at various pressures
Authors: Rostami Shamsedin , Walsh David J. 
Published: December 2004

AbstractA procedure is described for the simultaneous prediction of the binodal and spinodal curves of polymer mixtures at various pressures using a form of the equation‐of‐state theory of Flory and co‐workers. The results of the calculation are compared with experimental results for the effect of pressure on the cloud points of both oligomer mixtures showing upper critical behavior and polymer mixtures showing lower critical behavior. The procedure successfully predicts the sign of the effect and its magnitude within the experimental and theoretical uncertainties for the systems studied.
Linear low density polyethylenes and their blends: Part 3. Extensional flow of LLDPE's
Authors: Schlund B. , Utracki L. A. 
Published: December 2004

AbstractThe uniaxial extensional flow at 150°C of 11 linear low density polyethylenes (LLDPE) and one low density polyethylene was measured in a Rheometrics Extensional Rheometer. The presence of silicone oil did not affect the results. However, large effects of the molding time were observed. For specimens molded for 14 min, strain hardening was not observed for any gas‐phase polymerized LLDPE. As the molding time was increased to 40 min, the strain hardening was quite apparent, the elongational viscosity nearly doubled, the equilibrium plateau vanished, and the maximum strain at break Increased by about 20 percent. Explanation for the molding time effects can be found in the concept of low entanglement density in the virgin gas‐phase resins. The entanglement increases with time at temperatures above the melting point. The specimens molded for longer time show strain hardening.
The melt rheology of chloro‐polyether and polyepichlorohydrin blends
Authors: Liming Lu , Kebin Li , Shijin Li 
Published: December 2004

AbstractThe melt rheological behavior of chloro‐polyether and polyepichlorohydrin blends was studied. It was found that both the coupled and uncoupled blends at different blending ratios are pseudoplastic, but there was a great difference in pseudoplastic behavior between them. All the blends obeyed the principles of temperature superposition and composition superposition for plots of shear stress vs. shear rate. A model is proposed to describe and predict the rheological behavior of the blends.
Molecular entanglement for rigid rod molecular composites: Poly(p‐phenylene‐2,6‐benzbisthiazole)/poly(hexamethylene adipamide)
Authors: Wiff Donald R. , Timms S. , Helminiak Thaddeus E. , Hwang Wen‐Fang 
Published: December 2004

AbstractThe entanglement molecular weight necessary for integrity of processed fiber and film for rigid rod molecular composites is discussed. The case presented is one where the matrix flexible coil polymer has a marginal molecular weight for entanglement. The molecular weight of the rigid rod reinforcement was increased to offset this deficiency. No significant phase separation was observed for solutions undergoing high shear. Steady state shear measurements on rigid rod molecule solutions show that the zero shear viscosity results agree very well with recent theoretical rigid rod molecule behavior predictions.
Styrene/butyl acrylate copolymerization with layer morphology: Kinetics and viscoelastic properties
Authors: Garcia‐Rejon Andres , Rios L. , Lopez‐Latorre L. A. 
Published: December 2004

AbstractStyrene/butyl acrylate copolymers with layer morphology were synthesized using an emulsion copolymerization process, The kinetic parameters studied include monomers composition, initiator and transfer agent content, feeding time, and monomer addition sequence. The final product consists of a homopolymer nucleus surrounded by concentric shells of copolymers with different composition; the initial composition is quite rich in the monomer that forms the nucleus while the process ends with an enriched layer of the second homopolymer. Since the middle copolymer layer tends to increase the compatibility among the original homopolyers, we expected to have a set of core‐shell products with completely different properties. However, the experimental results showed that this was not the case. The composition effect on the viscoelastic properties shows, on one hand, that an increase in the butyl acrylate content lowers the elastic response of the final product, and on the other hand, that the elasticity increases with copolymer content. As the initiator content in the reaction media increases, the viscosity of the coreshell products decreases because of the existence of a media flooded with free radicals. If the butyl acrylate is first added, a graft polymerization is favored because of the polar nature of this homopolymer and, therefore, the molecular weight level increases.
The nucleation of microcellular thermoplastic foam with additives: Part II: Experimental results and discussion
Authors: Colton J. S. , Suh N. P. 
Published: December 2004

AbstractExperiments were performed to validate the model for the nucleation of microcellular foams in amorphous thermoplastic polymers. The polystyrene‐zinc stearate system was chosen as the model system. Other additives such as stearic acid and carbon black were also investigated. Molecular weight and orientation effects were studied. Nitrogen and carbon dioxide were used to produce the microcellular bubbles. Results show that amounts of soluble additives at levels just below their solubility limit and high gas saturation pressures yield the most acceptable foams—ones with a large number of uniform small bubbles. In this region, the bubble number is sensitive to both the gas saturation pressure and the concentration of solutes. Increasing the concentration of soluble additives above the solubility limit has little effect on bubble number and almost eliminates the dependence on saturation pressure. Molecular weight and orientation had no effect on the number of bubbles produced. Similarly, carbon black, which is insoluble in and which bonds well to polystyrene, produced no effect on bubble numbers. The agreement between theoretical predictions and experimental results is reasonably good.
Structural investigations of powder processed poly(phenylene sulfide) blends
Authors: Nadkarni V. M. , Radhakrishnan S. 
Published: December 2004

AbstractThe crystalline structure and morphology have been investigated for powder processed poly(phenylene sulfide) blended with high‐density polyethylene and poly(tetrafluoroethylene). The crystallinity in the former case showed large deviations from those estimated from rule of mixtures, while in the latter blends it closely followed the values predicted from the linear relation for homogeneous mixtures. Pronounced changes in some reflections were found in the X‐ray pattern on thermal curing of the samples. These results have been explained on the basis of compaction behavior of the powder blends together with the orientations induced during the processing steps.
Properties of biaxially oriented Nylon 66 film
Authors: Kohno Mitsuo , Tamemoto Kazuo 
Published: December 2004

AbstractBiaxially oriented Nylon 66 film has been developed by a new tubular process. The relationship between the structure resulting from the manufacturing conditions and properties have been examined. A key technology of manufacturing is quenching of the melt, because of the high rate of polymer crystallization. The properties of biaxially oriented Nylon 66 film are found to be determined mainly by the degree of polymerization, the molecular and hydrogen bond plane structure, orientation within the film, and the degree of crystallinity. Toughness and high thermal resistance are also properties of this film. Therefore, applications for packaging have been examined, and a “retortable pouch” seems especially promising.
Mechanical properties and permeability of polypropylene and poly(ethylene terephthalate) mixtures
Authors: Bataille P. , Boissé S. , Schreiber H. P. 
Published: December 2004

AbstractThe synthetic membranes currently used for soil stabilization and road construction are mainly made of polypropylene and of polyesters. They are used separately for each application. The polymer used has an effect on the wettability and, the permeability of the membrane. The polypropylene membranes, for instance, have a zero wettability, whereas it is high for polyester membranes. This paper reports on the mechanical properties and the permeability of mixtures of polypropylene (PP) and poly(ethylene terephthalate) (PET). The elastic modulus of the mixture was at a minimum for a 50/50 mixture. For the other compositions, the moduli gave a positive deviation as compared with the additivity equation results. This is probably due to the fact that pure PET has a fragile behavior at the temperature at which the mechanical tests were run. This 50/50 composition corresponds to the domain where a phase inversion occurs. The permeability to water vapor gave an S‐shape curve that is typical of a “mixture” of immiscible polymers. The diffusion of the water molecules is controlled by the continuous phase. To compatibilize the two homopolymers, a 94/6 copolymer of PP and of polyacrylic acid was added, at various levels, to a 60/40 mixture of PET and PP: This did not affect markedly the elastic modulus. The yield stress increased, however, indicating that we had a better adhesion and that the copolymer seems to have a certain emulsifier effect, increasing the quality of the dispersion.
Fracture toughness of urethane‐modified methacrylate resins
Authors: Sterrett Terry , Wong Ray , Kidd Patrick 
Published: December 2004

AbstractThis paper reports the synthesis of a series of urethanetoughened methacrylate resins and evaluation of the fracture toughness (KIC) of these materials. The incorporation of high‐molecular‐weight polyfunctional urethanes produced resins with the best mechanical properties, important to applications as dental biomaterials.
Aliphatic polyurethane elastomers with high performance properties
Authors: Dieter Janice W. , Byrne Catherine A. 
Published: December 2004

AbstractA new diisocyanate, 1,4‐eyclohexane diisocyanate (CHDI), has been used in a series of polyether‐based polyurethane elastomers. The slightly opaque samples are semicrystalline in nature with high performance properties, including high softening temperature, very good thermal stability, high tensile and tear strengths, excellent solvent resistance, and low hysteresis in compressive fatigue. Polymer properties are in part due to the small, compact, symmetrical structure of the aliphatic CHDI. Comparison of the physical, mechanical, and thermal properties of polyurethanes prepared from the aliphatic diisocyanate 4,4′‐dicyclohexylmethane dilsocyanate (H12MDI) reveal the H12MDI polymers to be more flexible and transparent elastomers with lower softening temperatures and tensile moduli and higher hysteretic heat build up. They are generally soluble in organic solvents.
Morphology in thermally oxidized high density polyethylene pipes
Authors: Gedde U. W. , Jansson J.‐F. , Terselius B. 
Published: December 2004

AbstractIn a continuation of previous work (1), the melting and crystallization behavior of the layered oxidized skin on thermally oxidized inner wall surfaces of different high density polyethylene (HDPE) pipes was studied. By hot stage polarized light microscopy on 5 μm thick cross‐sections of the skin, melting was shown to proceed successively as a front moving inwards as temperature was raised. Analogously, crystallization of the skin layers proceeded with the front advancing outwards towards the skin surface at decreasing temperature. The kinetics were followed and the data was compared with previous DSC thermograms (1) on similar samples. The high temperature melting peak of the oxidized skin reported in earlier DSC‐work (1) is shown to be associated with material with normal spherulitic texture.
Some problems associated with the puncture testing of plastics
Authors: Carapellucci L. M. , Yee A. F. , Nimmer R. P. 
Published: December 2004

AbstractGlassy polycarbonate specimens with different degrees of aging were tested in puncture for the purpose of determining the ductile/brittle transition temperature in biaxial tension. The results show that increasing amounts of aging increase the transition temperature from −95 to −70°C. All transitions appear too low In temperature. This was confirmed by using strip‐biaxial specimens that become brittle at a significantly higher temperature. In addition to this problem, the load deflection curve also can lead to an overestimation of the load and energy to initiate cracking. A finite element model of the puncture test suggests that the compressive stress under the dart may have shifted the onset of brittleness to much lower temperatures.
Rate process analysis applied to the mechanical behavior of glassy bisphenol‐A‐polycarbonate
Authors: Mattioli Theresa K. , Quesnel David J. 
Published: December 2004

AbstractThe mechanical behavior of bisphenol‐A‐polycarbonate has been studied. The principle mode of deformation studied was fatigue with monotonic tests and stress relaxation tests also performed. Testing was conducted at different strain rates and polycarbonate was found to be a rate sensitive material. In addition, it was found that polycarbonate's data show a good fit to the rate process theory of deformation first proposed by Eyring, whereby molecules move over a potential barrier in an activated process. A hard ball model is presented as a first approximation to this activated process of deformation. Finally, a potential mechanism of deformation during fatigue loading is discussed.
Orientability of liquid crystal polymers in elongational flow
Authors: Kenig S. 
Published: December 2004

AbstractThe orientation development in elongational flow (spinning) of liquid crystal polymers (LCP) has been studied and a physical model derived which relates the modulus development and extensional deformation. The model defines an orientability parameter, λ, which in addition to the total elongational deformation (drawdown ratio) are related to the orientation (modulus) level of the final spun fiber. Five LCPs were included in the study—a lyotropic polymer: Poly (p‐phenylene‐terephthalamide) and four wholly aromatic naphthalene‐containing polyesters. The experimental results have shown good agreement with the proposed model and indicate that λ is independent of the spinneret size and is characteristic of the orientability in elongational flow of each of the polymers investigated.
Small angle and wide angle x‐ray pole figure studies on simultaneous biaxially stretched poly(ethylene terephthalate) (PET) films
Authors: Cakmak Mukerrem , Spruiell Joseph E. , White James L. , Lin J. S. 
Published: December 2004

AbstractBiaxially oriented poly(ethylene terephthalate) (PET) films have been characterized by small angle and wide angle x‐ray scattering. The films were studied at various rotational angles to the impinging beam and orientations relative to axes in three directions in the film were obtained. Pole figures were developed for both the major small angle scattering peak and wide angle diffraction peaks. These are used to interpret structural changes in the films associated with various degrees of biaxial stretching and subsequent constrained annealing.