bluuebunny/crossref_metadata_2025_split huggingface dataset:
The mechanical behavior of springy polypropylene
Authors: Cannon S. L. , Statton W. O. , Hearle J. W. S. 
Published: December 2004

AbstractTo obtain further details of the unusual behavior of the “hard elastic,” “springy” form of polypropylene (SPP), various loading conditions were studied with an Instron model 1130. Specifically, the variation of the elongation at rupture with change in gauge length and strain rate has been determined. The nature and degree of the specimen hysteresis resulting from various loading cycles have been characterized. The ability of this material to recover from large extensions customarily expected to be permanent deformation has been identified and the time dependency of this recovery has been determined for strain levels of 10, 25, 50, and 100 percent of the original sample length. The effects of submitting the material to conditioning treatments, e.g., immersing in saline solutions of various electrolyte concentrations and autoclaving for 30 min at 250°F and 15 psig have been studied. Characterization of the stress relaxation behavior of the polymer has been made. Fatigue behavior has been identified utilizing a novel testing apparatus which permits load‐cycling of the fiber. Rheovibron work has facilitated calculation of the activation energy of the second order relaxation of SPP from tan δ vs temperature data. Stoll abrasion testing results on SPP tubular knit fabric and multifilament yarn have been compared to normal polypropylene and Dacron®.
Thermoplastic urethane elastomers IV. Effects of cycloaliphatic chain extender on dynamic mechanical properties
Authors: Seefried C. G. , Koleske J. V. , Critchfield F. E. , Dodd J. L. 
Published: December 2004

AbstractThe dynamic mechanical properties of a series of thermoplastic urethane elastomers have been studied as a function of molecular composition and temperature. Polymers based on polycaprolactone diol, an isomeric mixture of tolylene diisocyanate and hydrogenated Bisphenol‐A as the chain extender were prepared at various relative concentrations of hard and soft segments. The glass transition temperatures of these polymers progressively shifted to higher temperatures as the relative hard segment content was increased. This variation was accurately described by the Fox relationship for amorphous copolymers. These results can be interpreted in terms of the relative degree of segregation between the segment of the block copolymers.
Fiber reinforced rubber modified polypropylene
Authors: Speri William M. , Patrick George R. 
Published: December 2004

AbstractReinforcement can improve the modulus, heat distortion temperature and thermal expansion coefficient of rubber modified polypropylene. These improvements canbe obtained with a minimum sacrifice in resin ductility and impact toughness. Our studies have shown that reinforcement with small discontinuous fibers can provide a material with a good balance of stiffness and impact strength. The combination of small potassium titanate fiber reinforcement, polypropylene homopolymer and an impact modifier can produce a material with a tensile modulus of 470,000 psi, a notched Izod impact strength of 4.6 ft‐lb/in. and a Gardner imact strength of 320 in‐lb. Glass fiber reinforcement produces similar improvements in stiffness and retains Izod impact strength but drastically reduces Gardner impact strength. Polypropylene resin viscosity has a profound effect on composite impact strength. Transmission electron microscopy showed that a correlation exists between EPDM rubber particle size and impact strength: as rubber particle size is reduced, impact strength is increased. A 5 melt flow rate polypropylene was found to have the viscosity required to adequately shear and disperse the impact modifier. The paper describes an approach to broadening the utility of polypropylene homopolymers. The properties and flow of these materials compare very favorably with medium impact ABS.
Power for multi‐section melt screw extruders
Authors: Kraybill Richard R. 
Published: December 2004

AbstractTheoretical equations for power dissipation and torque for single and multi‐section screw extruders for Newtonian or slightly non‐Newtonian melts are derived from improved theoretical velocity distributions. Verification of the equations is indicated by experimental data for four single‐section screws of constant channel depth. The power equations can be easily programmed on a digital computer for design or evaluation.
Basic aspects of structure‐property relationships for composites
Authors: Charrier J.‐M. 
Published: December 2004

AbstractA composite normally consists of a material forming a continuous matrix and a different material in the form of discrete particles. The composite structure is characterized by the proportions of each component, the shape of the particles and their arrangement in space. A generalized way to characterize a particle shape and its position relative to adjacent particles is shown to describe the various geometrical arrangements of two components in space. The components of a composite often have different transport or related properties, i.e., thermal or electrical conductivity, gas permeability, modulus of elasticity, etc. A given property of a composite is a function of the structure of the composite and the corresponding property of each component. Structure‐property analytical relationships are presented and compared. A generalized relationship corresponding to a generalized particle is discussed and shown to be practical and realistic.
Environmental effects on fiber‐reinforced composites
Authors: Heller R. A. , Brinson H. F. , Thakker A. B. 
Published: December 2004

AbstractThe use of fiber‐reinforced composites in structures is discussed with emphasis on the need for a method to obtain long time properties from short time tests. Results of vibration, constant strain‐rate and creep tests are presented for boron epoxy laminates. The data is statistically conditioned and a time‐temperature shifting procedure is used to obtain master curves for response at an individual temperature. Three analytical linear viscoelastic characterization techniques are used to obtain long term creep response from dynamic data. Comparisons between analytical predictions are given for vibration and constant strain‐rate data. Creep predictions are also compared to experimental observations.
Co‐extrusion of unfilled and TiO2‐filled polyethylene: Influence of viscosity and die cross‐section on interface shape
Authors: Minagawa Nobuhiko , White James L. 
Published: December 2004

AbstractAn experimental study of the co‐extrusion of polyethylene and TiO2‐filled polyethylene through capillary and rectangular cross‐section dies has been carried out. The influence of viscosity ratio, cross‐section type, die length and duration of flow has been studied. Low viscosity melts will encapsulate high viscosity melts during flow through cylindrical and rectangular dies. Low viscosity unfilled melts can encapsulate higher viscosity filled melts and low vicosity filled melts can encapsulate higher viscosity unfilled melts. However, the rate and extent of encapsulation seems to be greater for the former case. This may be due to differences in the viscosity‐shear stress behavior of the filled and unfilled melts. In rectangular dies, the extent of encapsulation for any pair is greater when the interface is initially perpendicular to the shorter cross‐section dimension. The results are consistent with the idea that encapsulation primarily depends upon the ratio of die length to initial interface length.
High speed molecular weight distribution
Authors: Dark William A. , Limpert Robert J. , Carter Jordan D. 
Published: December 2004

AbstractIt is now possible to do molecular weight distribution of polymeric material almost as fast as you can put them in solution. μSYRAGEL® has opened a new era in the determination of molecular weight distribution of polymers. With operational efficiencies of 800 plates/min., one can obtain a molecular weight distribution in 15 mins. Combining three of the newest advances in liquid chromatography—solvent delivery, septumless injection, and μSYRAGEL—now makes it possible to use molecular weight distribution as a quality control tool in polymerization and fabrication. The reproducibility of the molecular weight distribution is now good enough that overlays can be done from the raw data. The chromatograms can be used right off the recorder. The reproducibility of the weight average and number average molecular weight is 2–3 percent.
The dry spinning process: Comparison of theory with experiment
Authors: Brazinsky Irving , Williams Albert G. , LaNieve H. Leslie 
Published: December 2004

AbstractTheoretical calculations based on a mathematical model of cellulose acetate dry spinning were compared with experimental data. Both experiment and theory indicate that the velocity in the spin line becomes essentially constant and equal to the take‐up speed at relatively short distances from the jet. Spin line diameter, however, continues to decrease with increasing axial position. Theory predicts that the filament diameter decreases rapidly at very short distances from the jet, but that the rate of this decrease tends to level off at greater distances. The experimental data exhibit similar trends. In addition, the theoretical and photographically observed spin line die swells are in good agreement. For a typical set of cellulose acetate extrusion conditions, computations show that within relatively short distances from the jet neither the diffusional resistance within the spin line nor the gas side mass transfer resistance in controlling. Both are significant. Calculations also indicate that both the filament and the gas side thermal resistances are important.
The SPE international award address—1975 polymerization by oxidative coupling—an historical review
Authors: Hay Allan S. 
Published: December 2004

AbstractThe history of PPO®, polymers of 2,6‐dimethylphenol, and Noryl® resins is described from the initial discovery through commercialization. The scope of oxidative polymerization as applied principally to phenols and acetylenes is outlined as well as the chemical reactions which can be performed on the resulting polymers.
A Comparison of Gel Permeation Chromatography and Liquid Chromatography for Epoxy Resin Analysis
Authors: Zucconi Theodore D. , Humphrey John S. 
Published: December 2004

AbstractGel permeation chromatography and liquid Chromatography are used for analyzing various epoxy resins. The chromatograms are compared with related information available from each. Because the separation is based on different principles, each method gives unique and different information about the same sample. For a complete analysis of epoxy resins, both techniques seem to be required.
High pressure non‐isothermal processing, of linear polyethylenes
Authors: Kulkarni K. M. , Broutman L. J. , Kalpakjian S. , Emery D. B. 
Published: December 2004

AbstractArticles with increased rigidity can be obtained by compression molding at high pressures as shown by experiments with five types of linear polyethylene. The materials, with weight average molecular weight ranging up to 1,000,000 were molded at pressures as high as 80,000 psi. The material temperature was 149–204°C, and the tooling was at 38°C. The duration of load was typically 3 mins, and the thickness of the molded disks was 12.7 mm. The results show that at high molding pressure the tensile modulus of the material is nearly twice that of materials molded conventionally at low pressures. This increase in modulus occurs for all the materials studied and even for a duration of load of only one min. The causes for this large increase in modulus were investigated with the help of density and melting point measurements and optical and electron microscopy. It was observed that the spherulites showed a distinctive and systematic change with the forming pressure. A hypothesis is proposed to explain the high modulus phenomenon on the basis of the kinetics of spherulite formation.
Extrusion of highly oriented polyolefin fibers
Authors: Collier John R. , Tam Thomas Yiu Tai , Newcome Jonathan , Dinos Nicholas 
Published: December 2004

AbstractThis study demonstrates that it is possible to extrude highly oriented polyethylene fibers using only a plasticating single screw extruder, specially designed and operated dies, and a simple take up mechanism. The degree of orientation achieved is as high as that achieved in solid state extrusion studies but accomplished at a fraction of the pressure. The degree of orientation is significantly greater than that of commercial grade fibers. The orientation is developed in the elongational flow of the “wine glass stem” region preceding the die entrance and is retained by crystallization in the die. Crystallization is inhibited in the pre‐die region by maintaining a temperature above the effective melting point of the flowing, oriented (hence lowered entropy) melt.
New aromatic silicon‐containing polyamides
Authors: Pratt J. R. , Johnston N. J. 
Published: December 2004

AbstractAs part of an ongoing program to prepare and evaluate thermally‐stable, processable materials, 18 aromatic, silicon containing polyamides (structures shown below) have been synthesized via interfacial polymerization of six silicon‐containing diacid chlorides with 3,3′‐diaminodiphenyl‐nethane, 3,3′‐diaminobenzophenone, and l‐(3′‐amino‐benzy)‐4‐(3″aminobenzoyl)benzene. All polyamides were soluble in m‐cresol and N,N‐dimethylacetamide and had glass transition temperatures between 178 and 254°C, Thermogravimetric analyses conducted in static air on film specimens were‐1 used to show 5 and 10 percent weight losses between 331–400°C and 354–440°C, respectively. magnified image3,3′‐ and 4,4′‐silane isomersR = R′ = Me; R = Me; R′ = Ph; R = R′ = Ph
Tris‐benzil crosslinked polyphenylquinoxalines
Authors: Rafter R. T. , Harrison E. S. 
Published: December 2004

AbstractPolyphenylquinoxalines (PPQ) were crosslinked with a tris‐benzil comonomer, to alleviate the inherenthigh temperature thermoplasticity, and evaluated as matrices in graphite reinforced composites. The room temperature flexural strength/modulus of Modmor IJ laminates were as high as 245,000 psi/16,6 × 106 psi. Essentially 100 percent retention of ambient mechanical properties was obtained at 371°C using a PPQ matrix from the fully‐crosslinked polymer prepared from 4,4′‐bis(4″‐oxybenzilyl) benzil (BOBB) and 3,3′‐diaminQbenzrdine. The degree of high temperature thermoplasticity in the composite was found to be more closely related to the final postcure temperature than to the BOBB crosslink density. The thermoplasticity essentially disappeared when the BOBB comonomer‐PPQ laminates were postcured at 482–510°C in nitrogen. Substitution of DMAC for the commonly used m‐cresol solvent system allowed facile preparation of prepreg to fabricate low‐void laminates and NOL rings.
Investigation of the Tll (>Tg) transition in polystyrene by torsional braid analysis
Authors: Gillham J. K. , Benci J. A. , Bover R. F. 
Published: December 2004

AbstractInvestigation of the Tll (>Tg) transition in amorphous poly‐styrene by the technique of torsional braid analysis is reviewed. For the most part, the relaxation behaves like the glass transition (Tg) in its dependence on molecular weight, on average molecular weight in binary polystyrene blends, and on composition in a compatible plasticized system.
The development of an instrumented projectile impact test: Data glass‐reinforced and impact‐modified polypropylene
Authors: Cessna L. C. , Lehane J. P. , Ralston R. H. , Prindle T. 
Published: December 2004

AbstractCharacteristics of several impact test methods in current use are discussed. The construction, operation and performance of an instrumented plate‐projectile (IFF) impact tester is described. Force‐strain curves, energies to any point in the test and failure modes may be inferred from the test data. Also, by inspection of the tested plate, one can see if there are cracks, blanching (development of microvoids) or ductile deformation. This inspection distinguishes between local and catastrophic failure—an important distinction in selection of materials for specific uses. There is reasonable correlation between values from notched Izod and IPP tests, with the latter somewhat more sensitive. Data illustrate the distinction between good and poor fiber‐to‐matrix coupling in reinforced polypropylene. Although there is some sacrifice of impact strength with improved fiber‐matrix coupling, this is more than counteracted by the improvement in static strength and creep resistance. The data show that coupled glass‐reinforced impact grade polypropylene exhibits an interesting balance of static to impact properties.
A new apparatus to measure the thermal conductivity and diffusivity of thermoplastic and thermosetting polymers
Authors: Sourour S. , Kamal Musa R. 
Published: December 2004

AbstractA new apparatus has been constructed to measure the thermal conductivity and the thermal diffusivity of reactive and nonreactive liquids and solids. The method used consists in suddenly subjecting the test specimen to a thermal flux and measuring the velocity of the heat wave across the sample. Maintaining the heat flux leads to a steady thermal gradient across the sample from which the thermal conductivity can be determined. The test duration is short relative to durations employed by existing conventional techniques and thus causes only a small thermal disturbance to the sample of the order of 1 to 2°C. Thermal properties of liquids and solids, including thermoplastics and a typical epoxy resin during cure with different equivalents of an aromatic diamine hardener have been measured near room temperature. Experimental data compare favorably with literature values for similar systems. Variations in thermal conductivity and diffusivity during cure have been obtained through a series of individual discrete measurements to cover the whole isothermal cure history. The results have been analyzed and discussed with respect to the cure characteristics of the resin and the nature of the physicochemical changes the material undergoes during cure.
Jetting phenomena in injection mold filling mold filling
Authors: Oda Kunio , White James L. , Clark Edward S. 
Published: December 2004

AbstractExperimental studies of injection molding of polymer melts have classified two regimes of mold filling–simple filling and jetting. In this paper we have examined a wide range of polymer melts and mold designs in an attempt to devise a criterion for the transition between these regimes. This criterion is found to be related to the extrudate swell d, gate diameter D, and small cavity dimension at the gate h. For isothermal mold filling, if d/h exceeds 1.0, the‐melt will contact the mold, stick to it, and induce a simple mold filling regime. The variation in behavior in vertical and horizontal mold filling is considered, as is the influence of barriers near the gate. For the non‐isothermal mold case, the manner of filling is similar, and the criterion for jetting remains the same, The die swell behavior in the non‐isothermal case is complex.
Stress measurement in polymeric materials by X‐ray diffraction
Authors: Barrett Charles S. , Predecki Paul 
Published: December 2004

AbstractExperiments are described which show that stresses in amorphous polymers can be measured by diffracting X‐rays at high Bragg angles from a filler consisting of crystalline particle or powders. The method is applicable, when calibrated, to both applied and residual stresses, to stress relaxation studies, to both tensile and compressive stresses, to both interior and surface positions in an object, and to composites of various types as well as to polymers that are substantially homogeneous. In the lower (Hookian) range, strains and stresses in metallic embedded particles increase linearly with applied stresses and strains in the matrix. When applied stresses exceed an apparent yield point, which correlates with the yield strength of the metallic filler, the elastic strains in the particles increase only slightly or even decrease as the matrix strains are increased, and with constant applied strain, the particles reveal changes due to relaxation. Strains in the particles are found to be smaller, and stresses higher, than in the matrix. Tests of graphite‐fiber epoxy composites with embedded filings of silver or aluminum alloy show that compressive residual stresses from curing at 350°C and cooling to room temperature are registered in the particles as well as stresses externally applied to the cured composite. Precision of the order of 1000 psi (0.7 kg/mm2 or 6.9 M Pa) was obtained with measurements made and evaluated rapidly and simply; with more refined techniques, much higher precision would be possible.
Increase of adhesive bond strength through the mechanochemical creation of free radicals Part II. Shear and peel test results
Authors: Lerchenthal Ch. H. , Brenman M. 
Published: December 2004

AbstractThe Part I paper described the mechanochemical basis for achieving high adhesive strength in bonds between polymeric surfaces such as polyethylene, polypropylene, and Teflon, using the SABRA method (Surface Activation Beneath Reactive Adhesives). This paper gives a brief survey of bonding techniques as well as results of shear tests of simple lap joints and scarfed tube joints. They compared favorably with other methods such as CASING, Peeling test results are also presented. Mixed systems were examined such as glass fiber reinforced polyester bonded to polypropylene and aluminum with thin films of polymeric material sandwiched between. A start was made towards of optimization and exploration of primer specificity for different materials, The implications and further applications of the SABRA method are discussed.
Influence of long‐chain branching on the viscoelastic properties of low‐density polyethylenes
Authors: Wild L. , Ranganath R. , Knobeloch D. C. 
Published: December 2004

AbstractMelt How data has been determined for a series of fractionated and whole low density polyethylenes which has been characterized in terms of their molecular weights and degree of long‐chain branching, (LCB). The resulting data indicate that low LCB influences melt flow both through a reduction in molecular size and an increased level of intermolecular interaction. Die swell measurements on whole polymers indicate an increase in melt elasticity with increase in degree of LCB for samples of similar melt flow (MI). Comparison of GPC data with observed die swell characteristics indicates that die swell is a molecular size dependent property and independent of intermolecular entanglement effects, suggesting that the measurement of elastic properties of LDPE melts will provide a means of determining relative degrees of LCB for commercial resins.
Extrusion of polymer tubing using a rotating mandrel
Authors: Shepherd G. W. , Clark H. G. , Pearsall G. W. 
Published: December 2004

AbstractA rotating mandrel in a tubing die produces multiaxial orientation in the extruded melt. If the polymer melt is quenched rapidly, some multiaxial orientation is retained in the resultant tubing. Multiaxially oriented tubing exhibits reduced crack propagation and some enhancement of yield and fracture strengths. During the processing of multiaxially oriented tubing, relaxation occurs after the melt leaves the die and gives rise to wall thickening and reduction in the lumen of the tubing; the magnitude of these effects is a function of the rate of mandrel rotation.