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  • 1980-1984  (4)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 987-995 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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 Quantimet image analysis system and dynamic mechanical analysis have been applied to characterization of crimped yarns. The image analysis system is useful for obtaining accurate measurements of crimps per inch, uncrimped versus crimped length, crimp wavelength, and crimp amplitude. In addition, the dynamic tensile mechanical properties of fibers and the dynamic compression mechanical properties of the fiber masses were examined. These analyses identify the relationships between crimp parameters and loss tangents for the first time. The loss tangents of fiber masses increase with increasing crimp frequency. The higher loss tangents of crimped yarns in the glassy region quantify both the internal friction of constituent fibers and the external fiber to fiber friction separately.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 25 (1980), S. 187-209 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Blends of an acrylonitrile copolymer and a reinforcing polymer were formed by polymerization of the second component in a concentrated solution of the first component. The second component, polyureas or polycarbodiimides, precipitated as an intimate dispersion of particulate domains in the liquid medium. Film or fiber formation by coagulation of the solution containing the second component as particulate matter resulted in a distinct two-phase blend. Reinforcement of the acrylonitrile copolymer was evidenced by significant increases in dry and wet moduli above the glass transition temperature of the polyacrylic component. The blends were characterized with dynamic mechanical testing and optical and electron microscopy. The blends exhibited two glass transitions corresponding to those of the individual components. The phase domains were evident over the compositional range examined. The method of blending is illustrative of effective reinforcement by interpenetration of phases in the absence of compatibility of the components at the macromolecular level.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 1871-1877 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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 dynamic mechanical properties of several polyurethane and polyolefinic elastomers for use in circulatory assist devices have been studied. This work was a part of a project on the characterization of elastomers suitable for cardiovascular application. In this paper, changes in the dynamic modulus and internal friction of these elastomers (Avcothane-51®, Biomer®, butyl rubber, Pellethane®, and Hexsyn®) are described as a function of long-term static and dynamic exposure to whole human blood. The dynamic moduli of control of Pellethane and Hexsyn are higher than that of Avcothane, NBS butyl rubber, and Biomer at human body temperature (at 37°C). The dynamic moduli of Biomer specimen fatigued in whole human blood at 37°C are least affected in temperature range of 25°C to 140°C as compared with the control. The loss tangents are decreased slightly. It indicates small structural changes after fatigue in whole human blood. These five materials should be considered for use in most or some cardiovascular applications because their mechanical properties do not change appreciably. Biomer performs well under a variety of experimental conditions, long-term exposure to blood, uniaxial and biaxial fatigue test, and dynamic mechanical properties of specimen fatigued in whole human blood.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 933-939 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Spinning speed is one of the most important process parameters for change in properties of yarn and efficiency of polyester production. In this paper the effect of spinning speed (3000-6200 ypm) on dynamic mechanical properties is presented, and shows a good qualitative picture on the influence of structure change on the dynamic modulus and the height and position of glass transition peak on POY (partially oriented polyester) and PTY (draw-textured polyester) yarns. The dynamic moduli of POY yarns in a temperature range of 25-160°C are increased with increasing spinning speed. Large glass transition peaks (α peak) are observed for POY yarn spun at 3000 and 2800 ypm at about 98°C. This indicates that the yarns are low oriented with low crystallinity (5-6%). But the Tg of POY spun at 5600 or 6200 ypm is about 125°C and shows about 35% crystallinity with high amorphous orientation. An approximately linear relation was found between the height of the loss peak (tan δ) and the degree of amorphous orientation (fa) by using these analyses.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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