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  • 2010-2014
  • 1985-1989  (726)
  • 1987  (726)
  • Chemical Engineering  (726)
  • 101
    Electronic Resource
    Electronic Resource
    Masthead (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760272201
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  • 102
    Electronic Resource
    Electronic Resource
    Structure formation during polymer blend flows (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1662-1674 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The structure formation processes that occur during the flow of dilute blends of high density polyethylene (HDPE) or polypropylene (PP) In a linear low density polyethylene (LLDPE) carrier phase have been studied. Due to low surface tensions, high deformations of the dispersed minor phase can be induced under slow flow conditions leading to the formation of slender filaments. Measurements on a slit die, having a large, converging flow entrance region, demonstrate that the mechanism for filament formation is droplet bursting, yielding growing tails during shear flow, or, unsteady drop elongation during extensional flow. Tail growth can be modeled as the flow of a slightly tapering cylinder in a fluid of different viscosity, For dispersed to carrier phase viscosity ratios greater than unity, extensional flow occurs in the tail phase, which can induce oriented crystallization. For ratios less than unity, the flow is compressive, which. Inhibits crystallization. Drop deformation and crystallization in the converging flow entrance region is greatly enhanced by the extensional flow, and droplet growth can be described by a model assuming a time-dependent, planar, extensional flow field. Data for birefringence and melting points of as-crystallized fibers are also presented and discussed.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760272204
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  • 103
    Electronic Resource
    Electronic Resource
    The formation of polymer fibers from the rapid expansion of supercritical fluid solutions (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1693-1697 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fibers of organic polymers (polystyrene, cellulose acetate, and polypropylene) were formed by the rapid expansion of supercritical fluid solutions through a small diameter nozzle to ambient temperature and pressure. Solutions were prepared either by dissolving the polymer directly in room temperature pentane, or in an autoclave at elevated temperatures and pressures for less soluble polymers. The fibers were collected on substrates mounted in the expansion jet. The diameters of the fibers formed (typically 1-5 μm) were much smaller than the opening of the nozzle, although fiber diameter was observed to generally increase with nozzle diameter. The aspect ratios of the fibers, produced by this process were on the order of 103 or larger. Optimum conditions for fiber formation occurred at fluid expansion temperatures near the melting point of the polymer, with particle formation mechanisms favored at higher and lower temperatures.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760272208
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  • 104
    Electronic Resource
    Electronic Resource
    The phase behavior and mechanical properties of polyarylate and polycarbonate blends (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1642-1648 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The phase behavior and mechanical properties of a series of polyarylate/polycarbonate blends were studied. The polymers are known to transesterify, the extent of which depends upon the thermal and shear history and affects phase behavior and properties. Single screw extrusion, twin screw extrusion, and solution casting were employed for blend preparation. Two transition temperatures, corresponding to a polycarbonate-rich phase and to a polyarylate-rich phase, were seen in blends that were solution cast or compounded in a single screw extruder at 285°C. But after injection molding a single Tg was observed, When annealed at 180°C for several hours the molded blend was found to phase separate. Blends that were compounded in a twin screw extruder exhibited a single Tg and could not be phase separated. The flexural and tensile properties of blends that were prepared in a twin screw extruder show a small positive synergism. But the impact properties were substantially below the rule of mixtures values, probably the result of advanced exchange reaction and thermal degradation.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760272111
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  • 105
    Electronic Resource
    Electronic Resource
    Dynamic fracture instability in glassy polymers as studied by ultrasonic fractography (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 25-32 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Ultrasonic fractography studies were performed on poly(methyl methacrylate) of high molecular weight. The transient fracture velocity change at the slow-to-fast transition during discontinuous propagation has been measured precisely. Fast fracture starts with a characteristic velocity which falls in a narrow range between 90 to 150 m/s, nearly independent of the loading speeds and the specimen temperature from -50 to 40°C. Parallel double-cantilever-beam specimens exhibited stick-slip type propagation whose velocity change was also evaluated. In these specimens, the fast fracture abruptly slows down to speeds on the order of 10° m/s. These intermediate velocities have never been obtained in the slow-to-fast transition. Velocity measurements under hydrostatic pressure have shown that fracture velocities decrease significantly with increasing pressure, and that the slow-to-fast transition tends to disappear at a pressure between 5 and 10 MPa. Models have been presented concerning the mechanism of the slow-to-fast transition, crazing and cracking under superposed cyclic stress field, and the relationship between dynamic toughness and fracture velocity in this material.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270105
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  • 106
    Electronic Resource
    Electronic Resource
    Fracture surface characteristics of unfilled thermosets (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 55-62 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Many of the features that cause the great complexity of the fracture surfaces of thermosets are suggested to have a simple explanation. These features include the “basic longitudinal texture,” “steps,” “welts,” “arrays of skewed cracks,” and the “stacked lamellar texture.” The explanation for their occurrence is based on the hypothesis of an instability of the propagating crack front that produces a “fingering” ahead of the crack.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270109
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  • 107
    Electronic Resource
    Electronic Resource
    Deformation and fracture characterization of inelastic composite materials using potentials (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 63-76 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An approach using strain energy-like potentials to characterize deformation and fracture of inelastic, nonlinear composite materials is described. The inelasticity may be due to various causes, including microcracking, microslipping, and rate processes responsible for fading memory (viscoelasticity). The concept of work potentials is introduced first, and then arguments are given for their existence for inelastic materials. Emphasis in the paper is on elastic composite materials with changing or constant states of distributed damage. Experimental results on polymeric composites are subsequently presented to illustrate this approach to deformation and fracture characterization. Finally, extension to viscoelastic behavior is discussed.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270110
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  • 108
    Electronic Resource
    Electronic Resource
    Flow distribution in spiral mandrel dies (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 186-191 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An analysis of flow of a power law fluid in a spiral mandrel die is presented. The analysis is applied to study the effect of various die design parameters on the flow distribution at the end of the spiral mandrel section. Three variables that have a very strong effect on the flow distribution are the number of grooves, the initial clearance, and the groove helix angle. The distribution is improved by increasing the number of grooves, by using a non-zero initial clearance, and a relatively small helix angle. Two more variables that have a significant effect on the flow distribution are the taper angle and the initial groove depth. The optimum taper angle was found to be between 1 and 3 degrees. The distribution uniformity improves with the initial groove depth, while the pressure drop reduces at the same time.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270303
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  • 109
    Electronic Resource
    Electronic Resource
    Fourier transform mechanical analysis for determining the nonlinear viscoelastic properties of polymersThis research was conducted as a part of the PhD dissertation of the first author in the Department of Mechanical Engineering. The University of Texas at Austin, 1982. (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 165-178 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fourier Transform Mechanical Analysis (FTMA) has been used to study the strain amplitude dependent nonlinear dynamic mechanical properties of two elastomer compounds, nitrile rubber (NBR) and Neoprene, at various frequencies up to 750 Hz. Basic theory and experimental results are presented for one-dimensional isothermal single frequency simple shear deformation. The Green-Rivlin constitutive equation was used to model the observed behavior. The energy dissipation mechanism and a physical meaning for the material functions in the Green-Rivlin representation have also been examined. The stress Fourier spectrum contained terms at the input frequency and its higher harmonics. It can qualitatively indicate the type of mathematical mode that best describes the observed behavior. The first harmonic storage and loss moduli showed strong dependence on the strain amplitude and frequency. The FTMA methodology presented can be used to systematically conduct nonlinear dynamic mechanical studies on any polymer. It can provide enough insight which, along with a knowledge of the molecular structure, may indicate a path for developing a better representative continuum constitutive model of these complex materials.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270211
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  • 110
    Electronic Resource
    Electronic Resource
    Thermal and cure analysis in sheet molding compound compression molds (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 218-224 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Sheet 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.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270307
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  • 111
    Electronic Resource
    Electronic Resource
    Masthead (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270401
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  • 112
    Electronic Resource
    Electronic Resource
    Dynamic mechanical properties and morphology of polypropylene block copolymers and polypropylene/elastomer blends (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 254-262 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The relation between the dynamic mechanical properties and the morphology of polypropylene (PP) block copolymers and polypropylene/elastomer blends was studied by dynamic mechanical analysis (DMA), light- and electron microscopy. The latter techniques contributed to an improvement in assignments of relaxation transitions in the DMA spectra. It was established that PP block copolymers had multiphase structure since the ethylene/propylene rubber phase (EPR) formed in the copolymerization contained polyethylene (PE) domains. An identical morphology was found in the case of PP/polyolefin thermoplastic rubber (TPO) blends. Impact modification of PP by styrene/butadiene block copolymers led to a multiphase structure, too, due to the polystyrene (PS) domains aggregated in the soft rubbery polybutadiene phase. In the semicrystalline polyolefinic and in the amorphous styrene/butadienebased thermoplastic rubbers, PE crystallites and PS do mains acted as nodes of the physical network structure, respectively. PP/EPDM/TPO ternary blends developed for replacing high-density PE showed very high dispersion of the modifiers as compared to that of PP block copolymers. This fine dispersion of the impact modifier is a basic regulating factor of impact energy dissipation in the form of shear yielding and crazing.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270404
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  • 113
    Electronic Resource
    Electronic Resource
    Studies of dissolution phenomena in microlithography (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 282-285 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: During the dissolution process, polymer in the glassy state is, transported into a dilute solution. In some cases, a transition layer can be measured using laser interferometry. This layer is seen as a difference in reflected light intensity between the bare substrate and the maximum during dissolution. When poly(methyl methacrylate) dissolves in methyl ethyl ketone, the layer is not detectable below a polymer number-average molecular weight of about 30,000. The layer becomes more pronounced as molecular weight of polymer increases.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270408
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  • 114
    Electronic Resource
    Electronic Resource
    Fatigue failure mechanisms in polymers (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 271-276 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fatigue testing of polymers has revealed significant differences between the fatigue response of polymers and metals. Generally, fatigue failure in metals is a process of crack initiation, propagation, and failure. Also, fatigue damage in metals is cumulative and cycle dependent, but remains essentially independent of test frequency. Unlike that of metals, the fatigue behavior of polymers is influenced by viscoelastic effects. At high frequencies, softening and melting occur, and fatigue failure depends largely on the test frequency. At lower frequencies, fatigue failure becomes less sensitive to test frequency and results from crack initiation and propagation. These polymer characteristics arise from the production of hysteresis energy during fatigue. A portion of this energy is released as heat, some of which is dissipated, but most is absorbed in the sample, raising its temperature. This temperature rise leads to degradation of the material and a short fatigue life. Experiments were conducted to measure hysteresis energy and temperature rise for a talc-filled polypropylene. A mathematical model was developed to calculate the energy and temperature distribution during fatigue. Correlation of the temperature rise predicted by the model with that observed experimentally provided values for the various energy terms that quantitatively defined the thermomechanical fatigue response of this polymer.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270406
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  • 115
    Electronic Resource
    Electronic Resource
    Linear low density polyethylenes and their blends: Part 2. Shear flow of LLDPE's (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 367-379 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The steady state and dynamic shear behavior of eleven commercial linear low density polyethylenes (LLDPE) and one low density polyethylene (LDPE) resin were measured in capillary and parallel plate geometries at T = 150 to 230°C. The extrudate swell and the Bagley correction were determined. A large pressure effect on capillary flow of narrow molecular weight distribution LLDPE was observed and a new corrective procedure was proposed. After the correction the steady state viscosity was found to be equal to the dynamic (not complex) viscosity: η(\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document}) = η'(ω = \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document}). A newly proposed four parameter relation between η and the deformation rate was found to provide a simple means for computation of the zero shear viscosity, ηo, and the primary relaxation time. Both these parameters showed a high degree of correlation. The expected relation: ηo ∝ Mw3.4 was observed for low molecular weight samples with low polydispersity. The LLDPE activation energy of flow, Eσ=29.9 ± 1.8 kJ/mole, was determined.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270510
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  • 116
    Electronic Resource
    Electronic Resource
    Linear low density polyethylenes and their blends: Part 3. Extensional flow of LLDPE's (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 380-386 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The 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.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270511
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  • 117
    Electronic Resource
    Electronic Resource
    The nucleation of microcellular thermoplastic foam with additives: Part I: Theoretical considerations (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 485-492 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Microcellular foam is a polymeric foam with bubble sizes of 10 microns or less that is produced by saturating a polymer with gas and then utilizing the thermodynamic instabilities that result when the polymer is heated and the pressure is reduced to nucleate the cells. A model for the nucleation of microcellular foam in amorphous polymers with additives has been developed. The nucleation process depends on the solubility, concentration, and interfacial energy of any additives present. At very low levels, additives in solution act to increase the free volume of the polymer, resulting in homogeneous nucleation within the free volume Well above the solubility limit, heterogeneous nucleation dominates, as it lowers the activation energy for nucleation to levels below that for homogeneous nucleation. In the vicinity of the solubility limit of the additive, these two nucleation mechanisms compete. The polystyrene-zinc stearate system has been chosen for experimental evaluation.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270702
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  • 118
    Electronic Resource
    Electronic Resource
    Numerical analysis of the temperature profile in the melt conveying section of a single screw extruder: Comparison with experimental data (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 504-509 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The prediction and measurement off the developing radial temperature profile in a single-screw extruder is essential since excessive extrudate temperature and poor temperature uniformity at the die affect the quality of coextrusion and film/sheet extrusion processes. A finite-difference scheme is used to predict the development of the radial temperature profile in the metering section of a single-screw extruder for power-law fluids. A finite-element analysis of the flow around the screw-tip transposes this temperature profile onto an on-line temperature measuring device consisting of 10 thermocouples for a comparison of numerical results with experimental data on polycarbonates.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270705
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  • 119
    Electronic Resource
    Electronic Resource
    Melt rheology of polyarylate/polybutylene terephthalate blends (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 529-534 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The viscosity, the activation energy of flow, and the exchange reactions of bisphenol A 50/50 isophthalic/terephthalic acid and poly(butylene terephthalate) blends are studied by means of an extrusion capillary rheometer, covering a range of 10 s-1 to 300 s-1 shear rate and 280°C to 300°C temperature. The results are interpreted in terms of compatibility and free volume additivity. The decrease in viscosity with time is explained as a result of transesterification rather than degradation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270709
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  • 120
    Electronic Resource
    Electronic Resource
    Masthead (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270801
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  • 121
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    Electronic Resource
    Polymer melt elongation - methods, results, and recent developments (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 537-546 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: For 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 η0(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.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270802
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    Minimum end time policies for batchwise radical chain polymerization. Part VI: The initiator addition policies for copolymerization with constant copolymer composition control (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 573-581 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: For batchwise radical chain solution copolymerization, the minimum end time problem with constant copolymer composition control is studied by considering the initiator concentration (or feed rate) and temperature as two control variables. During copolymerization, the more rapidly depleting monomer is continuously fed to the reactor to maintain the comonomer ratio constant. The volume variation due to contraction during copolymerization, in addition to monomer and solvent feeding, is also considered. It is found that the optimal initiator addition policy is to make the rate of initiation (2fkdIV) constant. The volume factor V is for taking account of volume variation. For the isothermal case, the number of moles of initiator in the reactor should remain constant. Experimental verification for acrylonitrile and styrene isothermal copolymerization with the proposed stepwise feeding of the more rapidly depleting monomer to simulate the optimal continuous monomer feeding policy shows that the present method is applicable.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270808
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    Masthead (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270901
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  • 124
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    Mechanical properties and permeability of polypropylene and poly(ethylene terephthalate) mixtures (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 622-626 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The 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.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270904
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  • 125
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    Mechanical and flow properties of high-density polyethylene/low-density polyethylene blends (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 640-646 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The 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.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270907
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  • 126
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    Fracture toughness of urethane-modified methacrylate resins (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 669-672 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This 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.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270911
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  • 127
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    Ionic impurities in water contained in plastic and pyrex bottles (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 611-614 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It is shown that most of the impurities in plastic bottles are not extracted by the water contained In these bottles. However, in the presence of water ions can easily be generated at 22 and 75°C in polyethylene, polypropylene, Teflon-FEP, and Pyrex bottles. Surprisingly, relatively large amounts of fluoride ions are extracted from Teflon-FEP bottles which contain very few contaminants. These ions greatly affect the electrical conductivity of the water which is linearly related to the ionic content. The plastic bottles containing the lowest ionic contents are those made in polypropylene and polyethylene. Sodium ions are also measured in the water contained in Pyrex bottles. It is also shown that acid rinsing of plastic containers is not a recommended cleaning technique.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270813
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  • 128
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    Rheological changes during the polymerization of polyurethane based interpenetrating polymer network(IPN) (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 716-726 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Experimental results on reactions forming polyurethanes and polyurethane-polyester Interpenetrating polymer network (IPN) are discussed with particular interest in rheological and kinetic changes before the gel point. In the IPN formation, viscosity rise is affected by the amount of styrene and polyester in the reaction system. Plots of reduced viscosity vs. conversion do not fall into a single curve. The results may be explained by the concept of having intra-molecular reaction or ring formation. The existence of hydroxyl group at the end of polyester molecule causes the graft reaction between the polyurethane phase and the polyester phase, which may speed up the viscosity rise of the reactive system. A simple method which based on rheological measurements only is proposed. This method of plotting reduced viscosity vs. reduced reaction time provides similar results as in the plots of reduced viscosity vs. conversion.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271004
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  • 129
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    Coupling between stresses and moisture diffusion in polymeric adhesives (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 731-739 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An experimental procedure is suggested for quantitative evaluation of the interdependence of stresses and moisture diffusion in polymer-dominated materials with special emphasis on epoxy resin based polymeric adhesives. It has been found that when such material is stressed in tension, the moisture diffusion rate increases; and when in compression, it decreases. At low stress levels, a linear relation was obtained between the coefficient of moisture diffusion and the applied stress, while at elevated levels it is nonlinear. Throughout the loading range, the coefficient correlates well with the volumetric changes in the stressed material.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271006
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  • 130
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    Optimization of the polycondensation step of polyethylene terephthalate formation in semibatch reactors (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 740-752 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The polycondensation stage of polyethylene terephthalate (PET) formation is assumed to include side reactions leading to the formation of diethylene glycol, vinyl end groups, and acid end groups, in addition to the usual polymerization of bis (2-hydroxyethyl) terephthalate (BHET) in semi-batch reactors. A, flexible objective function has been proposed with temperature and pressure as control variables. Computations from the first variation technique show that the pressure should be reduced to the lowest limit under all possible conditions. Consequently, optimal temperature profiles in batch reactors are obtained for various lower limits of reactor pressures using the combination of first and second variation techniques. For the first variation technique, the vector iteration method of computation was used, and the near optimal profile so obtained was used as the initial guess for the second variation technique. The result of optimization shows that the lower limit of pressure and weighting parameters appearing in the objective function have profound effects on the optimum profiles. For higher pressures, it is shown that a high temperature must be used initially; but must be lowered later to minimize the formation of side products. However, for lower pressures, the temperature must be increased from a low value initially; but for large polymerization times, the temperature must be further reduced to minimize the formation of side products. It is thus seen that the optimum temperature profile for low pressures exhibits a broad maximum.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271007
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    The calorimetric and mechanical properties of virgin and recycled poly(ethylene terephthalate) from beverage bottles (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 796-803 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In 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.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271105
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  • 132
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    Tensile yield in polypropylene (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 823-828 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Untaxial tension tests to the yield point were performed on polypropylene as a function of temperature from 22 to 143°C at a strain rate of 2 min-1. At 22, 42, and 71°C, measurements were also made at strain rates from 0.02 to 8 min-1. Yield energy was found to be a linear function of temperature extrapolating to zero at the melting point (164°C). The ratio of thermal to mechanical energy to produce yielding is about three times smaller than for glassy polymers. The ratio of yield stress to (initial) Young's modulus is about 0.024 at room temperature and increases to 0.043 at 143°C. Yield stress is a linear function of unstrained volume.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271109
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  • 133
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    Rate process analysis applied to the mechanical behavior of glassy bisphenol-A-polycarbonate (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 848-856 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The 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.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271113
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    Surface modifications of polymers with fluorine-containing plasmas: Deposition versus replacement reactions (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 861-868 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Surfaces of polyethylene; poly(vinyl fluoride), poly(vinylidene fluoride), poly(tetrafluoroethylene), cellulose acetate butyrate, and polyoxymethylene were modified in various cold plasma reactions; feed gases to the plasma reactor were trifluoromethane, hexafluoroethane, and tetrafluoromethane. Using X-ray photoelectron spectroscopy (ESCA) to characterize the surfaces, it was established that the plasma reactions lead to fluorinated surfaces containing —CF3, —CF2, and —CF groups, All of these fluorinated surfaces exhibit advancing contact angles (with water) larger than 900. However, differences in the ESCA spectra, weight-gain/-loss measurements and scanning-electron-microscopy (SEM) photographs reveal that the mechanisms of fluorination in the various plasma environments are markedly different. The CF3H gas polymerizes in the gas phase of the plasma and deposits a smooth, fluorinated film on polymers and other substrates. The C2F6 plasma simultaneously etches polymers and polymerizes onto polymer surfaces. The CF4 plasma etches and reacts with the polymer surface but does not polymerize. For polyoxymethylene, the combined roughening (by etching) and fluorination of the surfaces lead to completely non-wettable surfaces (water contact angle approximately 180°). The highly non-wettable surfaces of these two polymers are believed to result from the physical etching and roughening at a very fine scale (approximately five micrometers) while the outermost surfaces are reacting to become highly fluorinated.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271115
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    Small angle and wide angle x-ray pole figure studies on simultaneous biaxially stretched poly(ethylene terephthalate) (PET) films (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 893-905 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Biaxially 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.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271205
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    Characterization of molecular orientation in injection-molded thermoplastics by transmission and reflection infrared spectroscopy (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 917-924 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Orientation in injection moldings of polypropylene (PP), polyethylene (PE), polyamide 6 (PA-6), and polystyrene (PS) was investigated by transmission and reflection infrared spectroscopy. Orientation of the surface was measured by the reflection method, the depth profiles of orientation and of the fraction of the crystalline phase were measured by the transmission spectroscopy of microtome sections. The maximum of orientation of PP lies in the subsurface layer (ca. 250 μm); the crystalline phase is oriented more than the amorphous one. The maximum of the depth profile of orientation corresponds to the minimum of the fraction of the crystalline phase in PP. The profile of orientation of PE Is similar; at the beginning (to a depth of about 500 μm) the parallel orientation of the c axis of the crystalline phase is the most distinct one, towards the center the orientation of the a axis passes from the perpendicular to the parallel one. Under the described molding conditions PA-6 is not significantly oriented, the fraction of the crystalline phase increases towards the center of the molding. Unoriented PA-6, the surface layer of which was removed by milling, has a highly oriented surface due to its mechanical treatment. No pronounced orientation of PS was observed under the molding conditions used.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271208
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    Thermo-oxidative degradation of polyolefins observed by isothermal long-term DTA (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 945-954 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Isothermal differential thermal analysis (DTA) is well known for measuring thermal stability of polyolefins by determining the oxidative induction time at elevated temperatures. Oxidative induction time, measured up to 7,000 hours and over a temperature range from 240°C to 120°C, has been used to study the stability of polybutene-1 and crosslinked polyethylene in the melt state. The Arrhenius plots of DTA results show that straight line extrapolation from high to low temperatures is not possible. Thermoanalytically measured oxidation induction times and mechanical failure in oven aging experiments agree for polybutene and crosslinked polyethylene, Measurements of molecular weight and of mechanical properties of polybutene-1 during the induction period of oven aging experiments at low temperatures revealed that molecular weight and tensile properties are not sensitive indicators for the beginning of aging. The state of deterioration can be estimated easier by measurement of residual lifetime in the isothermal DTA experiment. Diffusion processes of stabilizers in polyolefins, as well as the consumption of stabilizer at elevated temperatures, especially during the induction period also was observed by DTA. Finally the extraction of stabilizer by hot water was measured by isothermal DTA.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271305
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    A technique for determination of stress fields in the contact loading of highly deformable polymeric materials (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 979-983 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Soft, deformable padding materials are widely used for the fabrication of cushions and pads used to reduce contact loading stresses in several industrial and biomedical applications. This paper, presents an indentation technique that can be used to evaluate cushioning materials. The technique uses a soft-headed indenter made of poly(vinyl chloride) gel that is impressed upon the polymer cushion to be tested. The strain fields and the high stress regimes that develop in the head are then mapped using a grid technique and finite strain theory. Results of indentation tests carried out on a number of cushions of varying stiffness are presented and analyzed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271309
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  • 139
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    Correlations of elastic modulus, cohesive energy density and heat capacity jump of glassy polymers (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1015-1017 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The elastic modulus of glassy polymers can be calculated from a measurable thermal property of polymers. The correlation of heat capacity jump data with molar modulus of 13 polymers indicated that the calculation of molar modulus from heat capacity jump energy for other glassy polymers is possible.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271314
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    Rheology of copolymers containing carbon black (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1043-1049 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The rheological response of random copolymers of styrene and butyl methacrylate containing carbon black simulates the behavior of toner in the electrophotographic process. Both the relative viscosity and the dependence of viscosity on shear rate were increased by raising the temperature and raising the concentration and surface area of carbon black. For high concentrations and surface areas of carbon black and at elevated temperatures, a well-defined yield stress varied from 2.5 × 102 to 1.6 × 104 Pa, depending on the concentration and nature of the carbon black but independent of the type of polymer and temperature, implying the formation of a carbon black network. Plasticization by carbon black was favored at low surface area and concentration of carbon black and at elevated temperatures.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271404
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  • 141
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    Effect of die temperature on the flow of polymer melts. Part I: Flow inside the die (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1079-1087 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of die wall temperature on the flow of polymer melts in circular capillary dies was studied. At constant flow rates, it was found that die wall temperature had a greater effect on the pressure drop than melt temperature. A capillary die with two circular channels with different diameters was designed to simulate the profile extrusion. Changes of wall temperature varied the flow rate ratio between the two channels. An implicit finite difference method was used to simulate the velocity and temperature profiles inside the die. Values predicted by this model matched well with experimental data for both dies.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271408
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  • 142
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    Internal mixing: A practical investigation of the influence of intermeshing rotor configuration and operating variables on mixing characteristics and flow dynamics (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1358-1370 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper deals with the measurement and interpretation of pressures and temperatures produced by the mixing of a rubber compound in the chamber of an internal mixer equipped with interlocking rotors. Pressure transducers and infrared/fiber optic temperature sensors were sited flush with the inner surface of the mixing chamber of a Francis Shaw KO Intermix of 2 L chamber volume. The variation of pressure with transducer position In the chamber wall and with rotor position was measured for selected fill factors and rotor speeds at “equilibrium” conditions (quasi-static power requirement for the mixer) and at intervals during a complete mixing cycle. Two rotor designs were studied. Interpretation of the results was carried out with reference to biconical rotor rheometer measurements on the mixed rubber compounds and by reference to four regimes of viscoelastic behavior identified for two-roll mill mixing. A basic flow analysis was carried out by use of the lubrication approximation in conjunction with an isothermal power-law model.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271803
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  • 143
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    Nonisothermal flow of a generalized power-law fluid in converging sections for rubber extrusion (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1371-1379 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A method for predicting pressure drop and temperature distribution in convergent sections is proposed. The generalized power-law rheological equation of state is used. Only the shear component of the converging flow is considered in order to estimate its contribution to total flow in such sections. A finite-difference scheme was used to simulate the flow. The method was applied to an ethylenepropylene terpolymer compound using different angles of approach for which the pressure drop and the extrudate temperature had been measured experimentally. Comparison with theoretically predicted data showed excellent agreement for small angles, while for large angles the inclusion of extensional effects was found to be necessary. The contribution of viscous dissipation effects was found to be negligible for the converging sections tested.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271804
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  • 144
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    Dynamics and control of pressure in the injection molding of thermoplastics (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1403-1410 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A detailed study was carried out to understand the dynamics of pressure variations at different points in the injection-molding system. Thus, hydraulic, nozzle, and cavity pressures were evaluated, in addition to the pressure gradient in the cavity. Both steps and pseudorandom binary sequences (PRBS) were employed to obtain and compare dynamic models describing these variables. Subsequently, these models were employed to evaluate and select optimal controllers for the different variables.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271809
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  • 145
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    Catalyst fragmentation during propylene polymerization: Part I. The effects of grain size and structure (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1436-1447 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fragmentation of support/catalyst particles during propylene polymerization in the gas phase is analyzed via a mathematical model including energy and mass transfer with chemical reaction processes. The rupture phenomenon is considered specifically by the model, and evaluated as it proceeds in time, Two different regions are recognized in the polymerizing particle at fragmentation time: an inner core resembling the original solid support/catalyst structure, and an external set of layers where most of the polymerization occurs. Model predictions concerning the effects of fragmentation on polymerization are discussed. The influence of different degrees of fragmentation on thermal runaways and monomer availability at active sites located inside the support/catalyst/polymer complex is shown. Monomer concentration profiles inside the growing particles are explained in terms of the combined fragmentation-polymerization interaction. Results show a strong influence of catalyst structure on critical phenomena during early polymerization stages, and suggest the possibility of controlling critical parameters via the definition of fragment structure at catalyst preparation time.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271903
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  • 146
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    Tensile creep tests, internal pressure tests, and scanning electron microscopy of electrical conduits of poly(vinyl chloride) (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1469-1472 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Electrical conduits prepared from a mixture of suspension and emulsion poly(vinyl chloride) (PVC) resins were subjected to internal pressure tests at 60°C, covering a wide range of pressures. Some axial tensile creep tests were also carried out at the same temperature. As expected, the ability to withstand internal pressure decreased when the amount of lubricant was increased above the level used in normai commercial production. Fracture surfaces obtained in the two test methods were investigated by scanning electron microscopy. Incompletely melted primary particles or other fragments of resin grains were not observed in any of the fracture surfaces studied in this work. However, a peculiar skinlike structure was found in the fracture surfaces formed at intermediate stress levels in the internal pressure test. This structure was not observed in the fracture surfaces obtained in the notched tensile tests at constant load.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271906
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  • 147
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    A contribution to the understanding of polyethylene/ionomer/polyamide-6 blends (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1495-1503 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It has been reported that the addition of specific copolymers can improve the mechanical properties of blends of polyethylene with polyamide-6. One of these, a poly(ethylene-co-methacrylic acid) (EMA) containing between 4 and 15 mol % of methacrylic acid units, has often been used. Binary polyethylene/EMA and EMA/polyamide-6 blends were studied with the hope that the role of EMA as a compatibilizer in polyethylene/EMA/polyamide-6 ternary blends might be better understood. Differential scanning calorimetry (DSC), laser small-angle light scattering, and mechanical property results are discussed. DSC measurements show that one component of the binary blends does not modify the crystallinity of the other. However, laser small-angle light scattering shows that the morphology of the mixtures changes under similar conditions. Tensile properties of polyethylene/EMA binary blends vary linearly as a function of composition, whereas those of EMA/polyamide-6 blends deviate slightly from linearity. These results indicate no interaction between the crystalline components of the mixtures, and weak interactions in the amorphous phase.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760272004
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  • 148
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    Structure-property-processing relationships of polypropylene-polybutylene blends (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1542-1556 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this paper we discuss PP-PB blends in which both components are highly crystallizable. It was our intention to try to prepare homogeneous PP-PB blends, assuming miscibility in the melt, by using the ultraquenching technique and to study the properties of the resulting blends following crystallization from the glass. Due to the possibility of preparing homogenous blends by ultraquenching, it should be interesting to compare the morphology, properties, and crystallization of the glass-crystallized blends with the melt-crystallized blends. We conclude that, in general, the above results suggest there is a considerable degree of compatibility, possibly even miscibility, of PP and PB in the melt, but that miscibility is difficult to obtain by ordinary melt mixing processes.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760272009
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  • 149
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    Preamble (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1573-1573 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760272102
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  • 150
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    Masthead (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760272001
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  • 151
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    Additives for improving the strength, stiffness, and ductility of epoxy resins (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1620-1626 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A range of additives at 7 to 20 wt% loading can increase the stiffness and strength of crosslinked epoxy resins by up to 60%, yet the tensile specimens also fail in a ductile fashion. In additive formulations where little chemical bonding occurs between the additive and the epoxy matrix (e.g., the reaction product of 4-hydroxyacetanilide and 1,2-epoxy-3-phenoxypropane), the increase in modulus is directly related to the decrease in free volume available for segmental mobility. The increase in strength results from a combination of the increased modulus and an increased fracture energy, A ductile mode of failure occurs because the cured plastic exhibits a large increase in free volume on straining (low Poinsson's ratio). The strain-induced increase in free volume effectively takes the sample through the glass to rubber transition. In more highly reactive formulations (e.g., the reaction product of 4-hydroxyacetanilide and vinyl cyclohexene dioxide), chemical bonding effects complicate this simple free volume interpretation, but the occurrence of a ductile failure mode is again related to the free volume increase with strain.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760272108
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  • 152
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    Masthead (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760272101
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  • 153
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    Structure-property relationships in polyamide/acrylonitrile-butadiene-styrene (ABS) blends (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1582-1590 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The structures and physical properties of four blends of poly(acrylonitrile-co-styrene-g-butadiene) (ABS) materials with polycaprolactam (PA6) have been characterized. The blends were separated into components by selective solvent extraction and were found to contain different structures: Blend A contained no PA6 grafts. Blend B contained PA6 grafted onto both soluble and insoluble ABS. Blend C contained PA6 grafted onto soluble poly(styrene-co-acrylonitrile) (p-SAN). In Blend D, PA6 was grafted onto both the insoluble ABS and the p-SAN phases. Transmission electron microscopy showed different morphologies in the blends. Blend A had a co-continuous, somewhat laminar structure, while Blend D consisted of an ABS phase dispersed in a PA6 continuum. Blends B and C had intermediate structures. All four blends, however, had very similar rheological and physical properties despite the variation in structure.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760272104
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  • 154
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    Rheological properties of linear low density polyethylene/polypropylene blends. Part 2: Solid state behavior (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1627-1633 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This second paper of a series continues the examination of the tensile properties of two series of linear low density polyethylene/polypropylene, (LLDPE/PP) blends. The blends were prepared using a twin-screw extruder and cover the whole concentration range, An Instron Universal Tensile Tester was used to measure the tensile properties of the blends between 10 and 70°C, and the temperature and composition dependences of the modulus were examined. A comparison is established between the solid state and melt properties to underline the behavior in the PP rich region. Results of dynamic mechanical experiments and differential scanning calorimetry on the same materials are also given, and the mechanical behavior is discussed in terms of the variation of the system's crystallinity.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760272109
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  • 155
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    Failure modes for polycarbonate under clearance-fit pin-loading (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1681-1687 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The failure modes and failure sequences for polycarbonate specimens loaded by a clearance-fit pin were investigated. Specimens were tested in various configurations to produce failures by different engineering failure modes. Photographs of the isochromatic fringe patterns were taken at different levels of damage development to examine the failure modes. A finite element stress analysis was used to explain the observed failure onset modes. Damage onset predictions were made based on a modified von Mises criterion. Failures involving net-tension damage initiated in the net-tension mode and failed ultimately in the same mode. Cleavage failures were observed for specimens with very small end-distances. Bearing failures were preceded by damage onset in a net-tension mode. Certain large-hole specimens failed in a buckling failure mode.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760272206
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  • 156
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    Masthead (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270101
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  • 157
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    Preface (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1-1 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270102
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  • 158
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    Stress-Cracking of high density polyethylene in detergents (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 82-85 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Correlations of the stress intensity factor, KI, with crack speed, ċ, have been obtained in a number of detergent solutions each having different detergent concentration. A constant crack speed region was observed in high density polyethylene. The KI independent constant crack speed was found to vary linearly with detergent concentration. The viscosity of the detergent solution increases with concentration and hence this region is not controlled by the hydrodynamic properties of the environment in contrast with Williams' model. The KI-ċ data were compared with existing models of crack propagation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270112
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    Preface (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 109-109 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270202
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  • 160
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    Masthead (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270201
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  • 161
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    Fracture of adhesive joints and laminated composites (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 77-81 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The 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.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270111
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  • 162
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    Effects of loading history on fatigue crack growth in high density polyethylene and toughened poly(methyl methacrylate) (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 110-115 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fatigue crack growth measurements are made on two grades of high density polyethylene (HDPE), of density 940 and 958 kg/m3, and on one transparent grade of toughened poly(methyl methacrylate) (PMMA). In both grades of HDPE, prolonged cycling is necessary to initiate a crack from a razor notch. Relationships between crack growth and stress intensity factor K are studied in all three materials. The results show that Paris plots of log (da/dn) against log ΔK are linear provided that: (a) the loading pattern applied to the specimen remains constant; and (b) growth has taken place for a sufficient period to eliminate the effects of previous loading history. However, da/dn is strongly dependent upon the ratio of minimum to maximum stress and upon the stress amplitude during previous cycles. Overloads cause accelerated growth which is followed by crack arrest when the stress amplitude is restored to its original level. The use of a transparent polymer enables a more detailed study of crack growth phenomena to be made during fatigue testing.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270203
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  • 163
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    Intermolecular interaction in polymer alloys as studied by crack healing (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 149-154 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The “method of crack healing” permits measuring the mechanical effects resulting from an interdiffusion of chain molecules across an interface. Having shown that in highly cross-linked ruptured styrene-acrylonitrile (SAN) a two-stage healing mechanism is active, a similar phenomenon was expected in blends of polystyrene (PS) with a more flexible component such as poly(vinyl methyl ether) (PVME), or with a more rigid component such as poly(-2,6 dimethyl 1,4 phenylene oxide) (PPO). However, in both cases crack healing at a temperature 10 K above the respective glass transition temperature (Tg) was linear with the healing time to the power of 1/4 and slower than with pure PS. This unexpected observation is explained by analysis of the thermal and viscoelastic behavior of these blends and by the different contribution to the stress intensity factor resulting from the entanglements formed by the interdiffusing molecules.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270209
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  • 164
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    The viscoelastic and aging characteristics of polymers (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 141-143 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The 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.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270207
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    An analytic study of tensile and puncture test behavior as a function of large-strain properties (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 263-270 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The 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.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270405
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  • 166
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    Unnotched impact bend test assessment of the degree of gelation in unplasticized poly(vinyl chloride) pipe (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 277-281 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It 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.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270407
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  • 167
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    A rheometer for concentrated polymer solutions containing volatile solvents (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 294-302 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new rheometer cell and integrated transducer, which is capable of performing both steady state and dynamic measurements in a controlled environment and at elevated temperatures and pressures, is described here. This cell mounts onto either the Rheometrics Mechanical Spectrometer or the Rheometrics System Four rheometer and utilizes the wide range of shear rates and frequencies available on these instruments. The unique capabilities of the rheometer and cell permit measurement of the rheological properties of concentrated polymer, solutions containing volatile solvents at temperatures above the normal boiling point of the solvent. The steady shear and dynamic properties of several polystyrene/ethylbenzene solutions having polymer concentrations greater than 50 wt percent are presented to demonstrate the performance of the rheometer.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270410
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  • 168
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    Preamble (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 313-314 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270502
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  • 169
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    The simulation of phase diagrams for polymer blends at various pressures (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 315-323 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A 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.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270503
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  • 170
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    Phase transitions during shear flow of two-phase polymer blends. I. Theory. Transition to “Homogeneous” melt state (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 344-350 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A hypothesis for critical conditions for a transition from a two-phase system to a homogeneous state during simple shear flow is advanced. It is predicted that at sufficiently high shear stress a homogeneous state is the stable steady state structure.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760270507
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    Masthead (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270501
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  • 172
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    A diffusion coefficient model for polymer devolatilizationPresented in part at the AIChE Annual Meeting, Session 146, Nov. 30, 1984, San Francisco, California. (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 303-312 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polymer devolatilizers are in widespread use in the polymer industry for removing solvents and monomers from polymer melts prior to product fabrication. Design equations for describing the solvent flux usually include both the diffusion coefficient of the solvent in the polymer melt and the equilibrium concentration of the solvent at the polymer-vapor interface. Several models make the as sumption that the solvent diffusivity is constant over the ranges of solvent concentrations and temperatures in the devolatilizer. This is a critical assumption that may be difficult to check without obtaining diffusivity data at the operating temperatures and concentrations of the process equipment. There are three models that can be used for diffusion coefficients in devolatilizer design: the free volume model developed by Duda, Vrentas, and coworkers; a new linear model proposed in this study; and a constant diffusivity model, The linear model is obtained by combining a new correlation for solvent activity coefficients in molten polymers with free volume theory and linearizing the resulting equation. The error between using the complete free volume theory and using the linear model, or alternatively, using a constant diffusion coefficient, is calculated for several solvent-polymer systems. The linear model is convenient to use for determining the effects of the solvent activity coefficient on the diffusion coefficient. A method is presented for determining whether the complete model, the linear model, or the constant diffusivity model is appropriate for a given devolatilizer design.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270411
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  • 173
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    Characterization and control of interfaces in emulsified incompatible polymer blends (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 328-334 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Information on the interfacial region in incompatible polymer mixtures can be gathered using various techniques including electron microscopy, thermal transition analysis, and more sophisticated methods such as nonradiative energy transfer (NRET). Selected examples are reported here to illustrate the exciting potentialities offered by diblock copolymer emulsifiers in controlling interfacial adhesion and devising high performance polymer blends.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270505
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  • 174
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    Spectroscopic study of poly(ethylene terephthalate)/poly(amide-6,6) blends (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 562-567 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fourier transform infrared (FT-IR) studies of poly(ethylene terephthalate) (PET)/poly/(amide-6,6) (PA) blends are presented. The blends were prepared in the molten state and in solution with trifluoroacetic acid (TFA) as the solvent. The PET/PA blend is a complex system containing, two crystallizable polymers with the ability to interact chemically. Some of the blends were prepared in the molten state in the presence of a catalytic amount of p-toluenesulfonic acid (TsOH) to undergo the ester-amide interchange reaction. Nuclear magnetic resonance (NMR) and FT-IR have proven to be excellent techniques with which to study these blends. 1HNMR was used to follow the ester-amide interchange reaction and FT-IR to detect the presence of hydrogen bonding. FT-IR studies showed the lack of hydrogen bonding in all the blends prepared in the molten state and its presence in the blends prepared in solution.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270806
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  • 175
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    Aliphatic polyurethane elastomers with high performance properties (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 673-683 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A 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.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270912
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  • 176
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    The glass transition of compatible blends (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 618-621 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In a thermodynamic model of the glass transition, general but circular relations for the compositional variation of the glass-transition temperature, Tg, can be derived from the entropy, the volume, and the enthalpy. The circumstances necessary for each of these to reduce to predictive relations are stated. Of these relations, that derived from the entropy should be the most general because of the expected rather wide applicability of the random mixing assumption, with which it is associated. The entropic theory is used to account for several aspects of the compositional variation of Tg, including problems not of solutions per se.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270903
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  • 177
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    Properties of polycarbonate/acrylonitrile-butadiene-styrene blends (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 632-639 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: To 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.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270906
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  • 178
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    Yield stress and flow measurements in ABA block copolymer melts (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 586-597 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A parallel-plate constant-stress rheometer is used to measure the yield stress τy, and the post-yield flow curve T(\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document}), where τ is shear stress and \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} is shear rate, for microphase-separated triblock copolymer melts. Five polymer samples, all styrene-butadiene-styrene but with differing composition ratios and molecular weights, are tested at 125°C. Specimens are prepared by casting sheets from solutions made with different solvents. The τ(\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document}) is found usually to be sigmoidal, for the range 10-5 〈 \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} 〈 10-3 s-1, representing different stages of microstructural degradation in flow. Measurements indicate that a true τy exists, with values in the range 100 〈 τy 〈 500 Pa for these melts. A general trend is detected for τy to decrease as the casting solvent solubility parameter increases. A scheme for correlating the dependence of τy, on composition and molecular weight is proposed for the various polymers. For selected samples, the effect of mechanical history (sequence of stress application) and a temperature variation that crosses Ts (110 to 150°C) are also explored.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270810
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    Masthead (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271001
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  • 180
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    Polymer sorbents for phosphorus esters: I. Selection of polymers by analog calorimetry (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 693-702 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Heats of mixing of a variety of solvents with dimethyl methyl phosphonate, DMMP, are presented. A qualitative correlation between the exothermicity of the heat of mixing of DMMP with a particular solvent and sorption of DMMP by polymers containing structural units analogous to the solvent is observed. By this approach, polymers containing acidic hydroxyl functionality, such as phenol-formaldehyde condensation products and poly(styrene-co-vinyl benzyl hexafluorodimethyl carbinol), were identified as good sorbents for DMMP. Sorption isotherms, measured for these materials by the piezoelectric method, show enhanced sorption at low vapor activity and 135°C compared to polystyrene and poly(vinyl chloride) which lack these acidic sites and whose solvent analogs mix more endothermically with DMMP.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271002
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  • 181
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    Morphology in thermally oxidized high density polyethylene pipes (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 727-730 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In 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.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271005
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  • 182
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    Practical aspects of physicochemical kinetics using thermal techniques (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 764-771 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A number of studies on the kinetics of physicochemical processes are described. The methods used are shown to be potentially useful for making time-temperature predictions and for optimizing process variables. Examples described include (1) the long-term prediction of the performance of a plasticized polyvinyl chloride and doped polyacetylenes; (2) the polymerization of a monomer and the optimization of time, temperature, and initiator concentration variables; (3) analysis of an order/disorder transition in a thermochromic polymer; (4) the crystallization of polymers and the effect of a nucleating agent; and (5) the crystallization of an amorphous metallic glass. The theoretical background, significance, scope, and limitations of these measurements are also discussed.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271009
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  • 183
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    The relationship between the equilibrium melting temperature and the supermolecular structure of several polyoxetanes and polyethylene oxide (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 781-787 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The relationships between equilibrium melting temperatures (Tm*) and crystalline morphology of poly[3,3bis(ethoxymethyl)oxetane], (polyBEMO), poly[3,3-bis (azidomethyl)oxetane], (polyBAMO), and poly(ethylene oxide), (PEO), were characterized. The Hoffman-Weeks extrapolation procedure led to Tm* values of 92, 102, and 69°C for these three polymers, respectively. The gross morphologies of polyBEMO, polyBAMO, and PEO were studied as a function of melt-liquid temperature (Ti) and isothermal crystallization temperature (Tc) by visible light microscopy. Spherulitic morphologies were observed for polyBEMO, polyBAMO, and PEO when Ti was above Tm*, while nonspherulitic (hedritic) morphologies were observed at Tls below Tm*. Mixed morphologies were observed when Tl was approximately equal to Tm*.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271103
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  • 184
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    Determining viscosity temperature behavior of four amorphous thermoplastics using a parallel plate technique (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 810-815 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The 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.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271107
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    A review of recent experimental results concerning the strength and time dependent behavior of fibrous poly(paraphenylene terephthalamide) (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 842-847 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A review of recent investigations of the strength and stress rupture of single filaments of poly(paraphenylene terephthalamide) (PPTA) is given. The experimental results are presented within an activation energy/power law breakdown framework. The statistics for tensile failure of individual filaments and epoxy impregnated strands and the lifetime of filaments in stress rupture are shown to fit the standard two-parameter Weibull distribution, as predicted from the model.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271112
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  • 186
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    Shelf life of phenolic resole resins (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 976-978 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Viscosity, 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.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271308
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  • 187
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    On the crystallinity and some structure/property relationships of poly(ethylene terephthalate) - poly(amide-6,6) blends (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 984-989 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Following the ester-amide interchange reaction in the poly(ethylene terephthalate)/poly(amide-6, 6) (PET/PA) system in the presence of p-toluenesulfonic acid (TsOH), samples were injection molded and tested in the tensile mode. A brittle fracture was observed for these unoriented specimens. To separate the influence of the crystallinity from that of the interphases, the samples were studied using differential scanning calorimetry (DSC). The DSC results indicated an increase of crystallinity in the blends caused by enhanced nucleation of PA (which crystallizes first) and that of the copolymer resulting from the esteramide interchange reaction. It has been independently verified that neat PET samples of comparable crystallinity to that existing in the PET/PA blends show a similar behavior.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271310
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  • 188
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    Elastic contact stress analysis of semi-crystalline polymers under normal and tangential loading (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 999-1005 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Stress 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.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271312
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  • 189
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    Rheology of polymers containing carbon black (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1035-1042 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In order to elucidate the flow behavior of electrophotographic toner systems, shear stress was measured as a function of shear rate in a cone and plate rheometer for polymer melts containing carbon blacks of surface area 24 and 625 m2/g at several concentrations and temperatures. Polymers included high and low molecular weight polystyrene and poly(butyl methacrylate). The addition of carbon black to the polymers caused a large increase in viscosity, especially at low shear rates and shear stresses. As the concentration of carbon black was increased, the viscosity at low shear rates became unbounded below a value of the shear stress designated the yield stress. The absolute magnitude of the yield stress depended primarily on the concentration and surface area of the carbon black and was independent of the polymer and temperature. Apparently, carbon black forms an independent network within the polymer at low shear rates which precludes flow. In some cases, the viscosity of polymers filled with carbon black was lower than that of the pure polymer. This effect was favored for polystyrene compared to poly(butyl methacrylate) and was facilitated by increasing the molecular weight of polystyrene, reducing the surface area and concentration of carbon black, and by increasing the temperature and shear rate.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271403
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  • 190
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    Residual stresses in injection-molded amorphous polymers (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1069-1078 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Nonisothermal flow of a polymer melt into a cold cavity and its rapid cooling give rise to the buildup of flow and thermal stresses in the molded article. In the present investigation the resultant residual stresses (RS) induced by these two sources were studied in two stages. First, the flow-induced stresses were relaxed by proper heat treatment followed by quenching, resulting in only thermal stresses. The experimentally determined RS profiles in polysulfone and amorphous polyamide showed a parabolic shape and were correlated with the initial and final quenching temperatures, the glass transition temperature, and Biot Number. In the second stage, the combined effect of thermal- and flow-induced stresses was studied using injection-molded specimens prepared under a wide speptrum of molding conditions including melt and mold temperatures and injection rate and pressure. Results here indicated that the basic thermal-induced parabolic RS profiles are altered by the flow-induced stresses resulting in complicated profiles including local maxima and unbalanced RS. Finally, the tensile mechanical properties obatained for plaques molded under the various injection-molding conditions were studied and correlated in part with the previously determined RS profiles. Results have shown that a property gradient exists as a function of distance from both the gate and surface of the molded plaque.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271407
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  • 191
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    Shear yielding of biaxially oriented styrene-acrylonitrile copolymer films (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1095-1104 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The shear yielding processes in the deformation of biaxially oriented styrene-acrylonitrile (SAN) copolymer films (machine oriented with draw ratio = 6.9 in the machine direction and 2.9 in the transverse direction) were studied. In the transverse direction, two sets of shear bands with an intersection angle of about 123.6 degrees (61.8 degrees with the tensile axis) were developed. When necking occurred, the bands in the necked region were thin and discontinuous with an intersection angle of about 81 degrees. In the machine direction, shear bands appeared to be short and diffused with an intersection angle of about 119.2 degrees. Only a slight necking effect was observed. The Luders strain in the transverse direction was about 0.56 and in the machine direction, about 0.16. The shearstrain-volume of activation obtained from the strain rate dependence of shear stress was about 3440 ± 400 Å3 in the machine direction and 2700 ± 500 Å3 in the transverse direction. The work hardening behavior in both directions seemed to follow a linear relationship between 1n (tensile stress) and tensile strain at large strains. From a consideration of localized shearing toward tensile axis, the fraction of deformed materials was calculated. These observations indicated that (1) a strong orientation hardening effect existed in unbalanced biaxially oriented films, resulting from the difference of the amount of deformable materials between individual directions; and (2) deformation proceeded by shear banding with the high orientation direction involved more correlated molecular segments than the low orientation direction during the activation process.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271410
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  • 192
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    Modification of butadiene-acrylonitrile rubber/poly(vinyl chloride) blend using natural rubber, styrene-butadiene rubber, and polybutadiene rubber (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1137-1140 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Natural 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.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271505
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  • 193
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    Melt spinning of (multifilament) poly(ethylene terephthalate) fibers: A simulation approachPresented in part at the 38th Annual II ChE metting, Calcutta, Dec. 1985. (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1050-1058 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An approach for modeling and simulation of multifilament melt spinning of poly(ethylene terephthalate) fibers is presented. It is shown that the quench conditions seen by the filaments within a bundle are not identical but differ for different rows of filaments. This, in turn, affects the spun fiber properties and introduces a degree of variability in the properties. The proposed approach allows determination of both the average properties and their variability for a given set of spinning conditions, spinneret geometry, and quench details.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271405
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  • 194
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    Effect of die temperature on the flow of polymer melts. Part II: Extrudate swell (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1088-1094 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of die wall temperature on the extrudate swell of polymer melts flowing through dies with single and dual circular channels was studied. Extrudate swell was measured at constant flow rates using an Instron capillary rheometer with a modified die section. It was found that under isothermal conditions, extrudate swell plotted against the average wall shear stress gave rise to a temperature independent correlation for polystyrene. Under non-isothermal conditions, such a correlation did not exist, which might be due to the change of wall shear stress in the axial direction. The extrudate swell in the non-isothermal cases can be better correlated with the wall shear stress at die exit. For the two-hole die, changes of die wall temperature varied both the flow rate ratio and the extru date swell ratio. The latter is, however, much less sensitive to the die wall temperature than the former.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271409
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  • 195
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    Influence of materials and structure on performance of a football helmet (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1113-1120 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A 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.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271502
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  • 196
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    Thermodynamic interaction in polybutadiene/solute systems by inverse gas chromatography (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1141-1147 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dependence of polymer-solute interactions on temperature In the range was 66 to 96°C was studied by inverse gas chromatography (IGC). A correlation equation was developed for estimation of the specific retention volume of nonpolar and slightly polar solutes in polybutadiene (PBD). Using equation of state solution theory, thermodynamic interaction was discussed in terms of contact energy and equation of state contributions in polybutadiene/solute systems. It was found that equation of state theory serves better than the Flory-Huggins theory as a comprehensive model to describe the temperature dependence of thermodynamic interaction.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271506
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  • 197
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    Characterization of polyethylene cable insulation by chemiluminescence measurements. I. Method developmentPaper presented at the International Symposium on Recent Advances in Polyolefins, Americans Chemicals Society National Meeting, Chicago, September 1985. (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1170-1181 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Chemiluminescence (CL) measurements have been performed on polyethylene electrical cable insulation. Matched pairs of unaged and aged materials were used where possible. The polyethylene materials investigated included crosslinked polyethylene, low density polyethylene, and ethylene-propylene rubber. Various experimental techniques were examined to see if any distinctions could be made between unaged and aged samples. Chemiluminescence spectra were obtained for the first time for these materials. The spectra show differences between materials and also between unaged and aged samples.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271510
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  • 198
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    Adhesive tack and green strength of EPDM rubber (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1195-1202 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Measurement of tack of EPDM (ethylene-propylenediene terpolymer) rubber with natural rubber (NR) of four different molecular weights, styrene-butadiene rubber (SBR), butadiene rubber (BR), bromobutyl rubber (BIIR), and polychloroprene rubber (CR) was done over a range of rates of testing, contact times, and temperatures of contact. The effect of different additives, namely carbon black, phenol-formaldehyde resin, coumarone-indene resin, and methyl methacrylate is also reported. Green strength of all the rubbers was measured. Tack strength increases with increase in contact time for all the rubbers. Adhesive tack between EPDM and low-molecular-weight NR is much higher than that between EPDM and NR of high molecular weight. Tack strength of EPDM with BIIR is the highest among the tack values obtained for synthetic rubbers. The adhesive tack between EPDM and natural/ synthetic rubber passes through a maximum when plotted against temperature of contact. It increases with testing rate. All these phenomena could be explained in terms of interdiffusion of rubber chains under different conditions and solubility parameter of two contacting rubbers. It was observed that tack strength varies with (contact time)1/2 and (rate)1/2 in accordance with the reptation theory. Phenol-formaldehyde resin (PF) or coumarone-indene (CI) resin in EPDM improves the tack strength quite significantly. The resin in the NR phase does not have a marked effect. The presence of carbon black decreases adhesive tack strength between EPDM and NR. The surface of EPDM, however, becomes smoother with the addition of the additives. Peel tests and commercial tack tests give similar results in the tack strength between EPDM/NR and EPDM/SBR.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271513
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  • 199
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    Masthead (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271701
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  • 200
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    An investigation of the blend of partially brominated poly(2,6-dimethyl 1,4-phenylene oxide) and polystyrene in the primary (glass-to-rubber) transition region (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1284-1291 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Compatible polymer blends can be used to test critically the viability of the damped Debye lattice (DDL) model of relaxation in the primary (glass-to-rubber) transition region. Since these blends form because of specific intermolecular interaction, the force constants that characterize intermolecular elastic interactions can be controlled to some extent by varying blend composition. The model predicts an unusual sharpening of the stress relaxation master curve of a marginally two-dimensional DDL upon dilution with a plasticizer. We have prepared an appropriate two-dimensional DDL by adding modest amounts of partially brominated poly(2,6-dimethyl 1,4-phenylene oxide) to polystyrene to form compatible blends. As predicted by the model, sharpening of the stress relaxation behavior upon dilution was observed for all blend compositions and for all diluents used. However, at higher brominated poly(phenylene oxide) concentrations, the anticipated diluent concentration dependence was not always observed and the sharpening of the stress relaxation behavior was less than expected. In similar experiments carried out on diluted homopolymers, the relative values of the solubility parameters of the polymers and the diluents strongly influenced the effectiveness of the diluent in changing the stress relaxation behavior. In this blend system, the particular chemical nature of the diluent was found to be much less important; in fact, the three diluents used all evoked approximately the same behavior despite their having solubility parameters that differed significantly.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271704
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