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  • 1
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Nylon 66 films exhibiting form I melting behavior show the γ mechanical relaxation at -140°C. Samples which have form II melting behavior do not show this relaxation. The γ relaxation disappears when material having form I behavior is converted to material having form II behavior by annealing or by cold drawing. The form I and form II types of melting behavior are also found in poly(ethylene terephthalate); the interconversions and thermal behavior of the forms are analogous to the nylon 66 case. In poly(ethylene terephthalate), the β relaxation at -40 to -60°C is present only when form I melting behavior is found. Conversion to form II melting behavior by annealing or drawing (80°C) again causes the relaxation to disappear. No β relaxation was found in amorphous polymer. The γ dispersion in nylon 66 and the β dispersion in poly(ethylene terephthalate) can therefore be associated with the crystalline structure responsible for form I melting behavior. Form I melting behavior has been associated with foldedchain crystals based on previous work. It is therefore postulated that the γ dispersion in nylon 66 and the β dispersion in poly(ethylene terephthalate) are associated with motions in the chain folds. This assignment is not inconsistent with the change in the γ dispersion of nylon 66 with the number of backbone CH2 units, since these will affect the fold structure.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A technique for the selective degradation of amorphous regions in nylon 6,6 is reported. Samples of unoriented film and single-crystal mats have been subjected to selective degradation by refluxing in hydrazine. Weight loss, viscosity-average molecular weight, density, and small-angle x-ray scattering of these samples were monitored as a function of time of degradation. In addition, selected samples have been investigated by gel permeation chromatography (GPC) and transmission electron microscopy. Based on the results of these investigations it is concluded that the reported degradation technique is unique in that the debris is not monodisperse in molecular weight distribution. The Weight loss, density, small-angle x-ray scattering, and microscopy data demonstrate that the unordered or noncrystalline regions of the material are removed upon treatement. However, the relatively high molecular weight and broad molecular weight distribution of the debris indicate that regular folds at lamellar surfaces are intact after degradation treatment.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Treatement with hydrazine was used to investigate the crystalline morophology of commercially drawn nylon 6,6 fibers. Electron microscopic investigation revealed a stacked lamellar structure for the debris of a highly oriented, rapidly drawn fiber. However, the high molecular weight range of the gel permeation chromatogram of this same oriented fiber indicated the presence of high molecular weight material. This is thought to be due to the production of rod-like, partially extended regions during drawing.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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