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  • Wiley-Blackwell  (6)
  • 1975-1979  (6)
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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1647-1654 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The infrared spectra of polyethylene single crystals suspended in liquid are reported and compared to dried mats of the same material. In order to observe the polyethylene bands, liquids with partial windows in complementary regions of the spectra were chosen. Any remaining bands of the suspending media were removed by substraction of the spectrum of the pure liquid. The crystalline bands of suspended polyethylene are much sharper than those of the dried material, indicating a decrease in lateral crystalline order upon drying. Drying also results in a change in the type and distribution of conformations associated with amorphous and fold structures, as determined by the observed frequencies of the methylene wagging mode.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 1253-1260 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A complex fine structure in the C—H stretching region of the infrared spectrum of deformed polyethylene single crystals is reported. The deformed crystals are shown to be transformed from the orthorhombic crystal form to a monoclinic structure. The previously deduced C2/m monoclinic structure does not account for the appearance of the new bands. An alternative but similar monoclinic structure is proposed. The symmetry of this structure is consistent with the Fermi resonance interactions required for the observation of these bands.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 63-71 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Recent experiments have supported the view that polyethylene (PE) single crystals kept in suspension, in a variety of liquids, have different physical properties compared with the same crystals after drying. The present work was undertaken in an attempt to directly measure one of the basic properties of crystals in suspension, namely their percent crystallinity (X). Differential scanning calorimetry was chosen as the primary tool for this investigation. A method has been developed to determine the weight of PE in a suspension of crystals in a nonsolvent. Thus, a determination of X can be made. For suspension crystals, X was found to be at least 88.5%, some 6% larger than that for the corresponding dried or freeze-dried material. Implications with regard to the fold-surface structure are discussed. Differences in degree of crystallinity as a function of drying procedure have also been observed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 375-377 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 321-328 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The melting points (Tm) of small quantities (ca. 0.1 mg) of polyethylene (PE) single crystals in the dried state and in suspension were determined as a function of heating rate. Melting points were also obtained for large amounts (ca. 3 mg) of dried-down crystals. It has been reported previously that PE crystals of high molecular weight possess a single melting point and this Tm decreases with increasing heating rate. However, all samples in our study show multiple melting behavior. Moreover, suspension samples show little or no variation in the various peak temperatures with heating rate. There is some dependence of Tm on heating rate for small dry samples but the change in Tm is not nearly as great as previously reported. These small changes can be the result of the relatively poor resolution of small dry samples compared to suspension. Differences between the behavior reported here and those of other authors can be explained on the basis of the relative contributions to the various melting endotherms.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 491-496 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The model of a tight-fold adjacent reentry fold surface for polyethylene single crystals has been questioned, because it has been speculated that a tight-fold surface should have a density approximating that of the unit cell (∼1.00 g/cm3). This would lead to an overall lamella density of close to unity. In contrast, the majority of measured values are in the range 0.96 to 0.97+ g/cm3. These lower values have been taken as evidence to disprove a tight-fold-surface model. The present calculations made on space filling models of tight folds indicates a fold surface density on the order of 0.75 g/cm3. This produces no inconsistency between a tight-fold model and accepted lamella density values. Further, calculated values of the weight fraction crystallinity of lamella, as a function of the number of carbons in the fold, limits this number to approximately 9 to 11 carbons per fold.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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