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  • 1
    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 synthesis of block copolymers and the study of their morphology were undertaken to find improved thermoplastic rubbers for service at elevated temperatures. The basis was the extraordinary properties possessed by ABA-type block copolymers in which the terminal blocks are polystyrene and the central block is either polyisoprene or polybutadiene. In these systems it has been well established that the unusual properties are a result of domain formation in which the hard and the soft blocks aggregate separately into distinct phases. The hard segment is thought to act both as a crosslink and as a filler. Block copolymers were synthesized with different soft and hard segments. The effects of these segments and of their properties on the morphology and the stress-strain properties of the block copolymers were measured and evaluated. Electron microscopy and birefringence were used to determine the morphology. It was found that the glass transition temperatures of the segments, the bulk of the monomer unit in the glassy segment, and the morphology determined the strength of the material. Some of the materials prepared have tensile strengths of 0.1 kg/cm2 or more at temperatures in excess of 180°C and therefore appear promising as elastomers for service at elevated temperatures.
    Additional Material: 5 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 17 (1973), S. 1377-1386 
    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 the epoxy resin of the diglycidyl ether of bisphenol A cured with varying amounts of a carboxyl-terminated butadiene-acrylonitrile copolymer were determined. Isochronal measurements were made between -90° to 170°C for eight compositions. Mechanical relaxations indicate the degree of interaction and the state of mixing of the two-phase system. Phase reversal occurs at a volume fraction of 0.5, where an intermediate compound is formed. In the low concentration range of the elastomeric phase, the impact strength improvement correlates well with an increase in the energy absorption of the relaxation. The known morphology of the system at this composition range allowed testing of various phenomenological mechanics models proposed to calculate the tensile properties of composite systems.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    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: Observations obtained by other techniques were confirmed by DSC analyses. As the length of the methylene chain increased, Tm decreased, and crystallinity, heat capacity, and heat of fusion increased. The Tm and crystallinity of the isophthalate esters were lower than for the corresponding terephthalate esters. The values for an odd-numbered methylene sequence were lower than for the adjacent even-numbered members. A model was used to calculate the heat of fusion of theoretically 100% crystalline poly(hexamethylene isophthalate) and poly(decamethylene isophthalate).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 4
    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 β-relaxation at Tg of the terephthalate and isophthalate series is due to molecular motions of the backbone chains in the amorphous region, but differs for the isophthalate series in that the p-phenylene group does not exhibit the free rotation possible for the m-phenylene group. Consequently, the relaxation times of the terephthalate series are longer than for the isophthalate series. The γ-relaxation (Tγ) for the higher homologues of the terephthalate series cannot be explained in terms of the poly(ethylene terephthalate) analogy. For poly(ethylene terephthalate) and poly(tetramethylene terephthalate), an induced cooperative type of motion of all the moieties is possible, whereby overlapping processes caused by “rocking vibrations” are observed as one γ-peak. The resolution of the γ-loss peaks for the above-mentioned polyesters into components is not possible at the experimental frequency of 110 Hz. For poly(hexamethylene terephthalate) and poly(decamethylene terephthalate), the “rocking vibrations” between the moieties of the skeletal chain are reduced so that even at a test frequency of 110 Hz, the γ-loss peaks could be resolved into two or three components. In the case of poly(decamethylene terephthalate), three components are resolved; the lowest temperature peak γ1 is attributed to hindered motions of the methylene portions, the γ2 peak is attributed to motions of the carbonyl group in the gauche conformation, and the γ3 peak is attributed to the carbonyl group in the trans conformation of the skeletal chain in the amorphous region. The general observations obtained by other techniques were confirmed by the forced vibration analyses. As the length of the methylene chain increased, Tg decreased. As crystallinity increased, the β-relaxation moved to higher temperatures and the damping peak was smaller and broader. The damping peak moved to lower temperatures and increased in size as the length of the methylene chain increased. The damping peak was larger for the isophthalate homologue than for the corresponding terephthalate polyester.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 3403-3423 
    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: Closed-cell foams based on rigid polyurethanes blended with more viscoelastic polymers possess good vibration-damping properties. The damping characteristics of the various polymers differ, indicating that the chemical nature has an influence on the acoustical performance of the blend. Damping is also temperature dependent. By selection of polymers, foam effective for damping at various service temperatures and over various frequency ranges can be made. The damping characteristics of polymers can be changed by adding fillers. Such methods may be employed to achieve a broader damping peak at the desired service temperature. The damping of vibration of an aluminum strip could be increased by one to two orders of magnitude between 20°C to 60°C when the strip was coated with the experimental materials in comparison with commercial open-cell, elastic foams of comparable density. A dynamic resilience of only 9% was achieved.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 6
    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: Four monomers were synthesized and four copolymers prepared. The polymers were dark-colored, poorly soluble, crystalline products. The x-ray photographs were typical of triclinic crystals. The polymers degraded at temperatures lower than those characteristic of the analogous homopolymers. The recovered polymers were ferromagnetic.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 7
    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 nylons 6, 11, 12, 66, 610, 612, and 666 are compared. The spectra are very similar with peaks in the loss curves at about -120, -40, and 85°C. The similarity suggests that attempts to determine whether the nylons could in fact be incompatible when blended might not be successful. Calculations based in turn on calculated cohesive energy densities and interaction parameters also suggest that only nylon, 6 and 66 would be compatible. By using the nature of the major loss peak at the glassy transition which is high and narrow for nylons 11 and 12 and broader and shorter for nylons 6, 66, and 666, it is possible to deduce that nylons 6 and 12 are somewhat incompatible but that the other combinations are most likely dynamically compatible.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 8
    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: A study of the nonlinear viscoelastic properties of polymers was made using the Halsey-Eyring model with one- and three-dimensional mathematical analyses. Various parameters to calculate stress-relaxation and creep could be calculated from a single stress-strain curve of the same polymer. The parameters so calculated reconstituted the stress-strain curves, the one-dimensional equations yielding the better fit. The same constants were applied to predict stress-relaxation and creep. The fit using the three-dimensional equations is much better for stress-relaxation and creep than the one-dimensional equations.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 40 (1990), S. 495-502 
    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 mechanical behavior of nylons 6,66,666,610,612,11 and 12 was studied using the method of thermally stimulated creep at 96°C. The resultant creep moduli were calculated. The strain recovery and strain recovery rates were measured and the retardation time spectra calculated as a function of temperature. The effects of humidity on the creep and subsequent recovery behavior were compared using samples conditioned to 0, 33, and 97% relative humidity at room temperature.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 10
    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: This paper presents data on the thermal, dynamic, and mechanical properties of polypropylene (PP) blends with bisphenol-A-polycarbonate (PC), to which a series of graft and block copolymers in a small quantity was added. The effect of the minor component on the crystallization and relaxation behavior of PP in the blends has been investigated and correlated with the mechanical properties obtained. The results demonstrate that the graft copolymeric additives to the blends can reduce the degree of undercooling (Tm°C - Tc°C) of the PP phase. However, the block copolymers used, substituting for the graft copolymers, showed no such function. Dynamic mechanical thermal analysis (DMTA) indicates that, with the addition of several different copolymers as minor additives to the blends, two loss peaks representing the glassy transitions (Tg) of the individual components (PP and PC) were retained, with little tendency of approaching toward each other, suggesting no obvious improvement in compatibility of the PP phase and the PC phase in the blends. Nevertheless, the inclusion of different copolymers in the PP/PC blends, in spite of the small quantity used (4%), can lead to a significant mechanical property difference of the blends. This difference could be reasonably explained from the data obtained in dynamic mechanical characterization of the different graft copolymers in PP blends.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
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