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  • 1
    Electronic Resource
    Electronic Resource
    SAXS instrumental broadening and the order dependence of peak width (1981)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 487-497 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The width at half-height of SAXS discrete diffraction peaks has been used to compute the number of polyethylene lamellae in a stack. The dependence of this width on diffraction order reflects the nature and magnitude of lattice fluctuations. Within the literature there have been conflicting reports on this order dependence and hence on the nature of the lattice fluctuations. Previous studies have neglected the effects of instrumental broadening. These present studies show that instrumental effects can account for some 40% of the observed first-order peak width and drastically change the ratio of peak widths as a function of order. These studies, carried out on isothermally grown polyethylene single-crystal mats, also demonstrate the importance of the functions chosen to represent the various broadening factors. A mat was made up consisting of randomly stacked lamella with two distinct fold periods. The scattering from this mixed mat could not be described by either of the prevailing theories.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1981.180190309
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of interlamellar forces on the longitudinal acoustic mode of polyethylene crystals (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1687-1693 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The fold periods and longitudinal acoustic modes [LAMs] for isothermally crystallized polyethylene (PE) single crystals were determined in the dried state and in the presence of decalin and silicone oil. Upon swelling with decalin, the fold period increased by 7% while the LAM peak frequency decreased by approximately 1 cm-1. Several possible explanations for the change in LAM frequency are discussed but the exact interpretation is open to question. No change in fold period was observed upon soaking a dried crystal mat in silicone oil. This fold period invariance along with the fact that silicone oil has no effect on the melting point of PE crystals indicates that there is no significant interaction between the oil and the methylene groups on the crystal surface. The effect of suspending crystals (which have never been dried down) in silicone oil should only be to increase the average interlamellar distance and, therefore, to reduce any interlamellar forces. It is shown that the LAM peak frequency for crystals suspended in silicone oil is the same as that for the dried crystals, indicating that interlamellar forces do not exert a significant perturbing influence on the LAM of polyethylene crystals.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.180200918
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  • 3
    Electronic Resource
    Electronic Resource
    The heating rate dependence of polymer melting points (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 321-328 
    Details
    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
    URL: http://dx.doi.org/10.1002/pol.1979.180170211
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  • 4
    Electronic Resource
    Electronic Resource
    Estimations of fold surface densities using space-filling models (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 491-496 
    Details
    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
    URL: http://dx.doi.org/10.1002/pol.1979.180170313
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  • 5
    Electronic Resource
    Electronic Resource
    SAXS determination of the amorphous surface layer thickness of polymer single crystals (1981)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1237-1243 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polyethylene single crystals were grown from 0.1% solutions in xylene at 80 and 87°C. Oriented mats were made from each preparation and the small-angle x-ray scattering (SAXS) profiles obtained. Following treatment of the raw data for main-beam position and width, background scatter, and the Lorentz factor, five Bragg reflections were resolved. A one-dimensional lattice was used as a model for the oriented mats of single crystals. This model contains three parameters. An additional parameter Gx was also introduced to demonstrate the general effect of a broadening factor on the model. The effect of each parameter on the calculated diffraction pattern was examined. From this examination it was found that by assuming that the broadening functions are zero we can determine directly from the number of observable peaks the maximum possible thickness of the amorphous surface. Further, we find that the thickness of the amorphous layer must be less than the maximum value calculated if Gx is assigned values greater than zero. A “best-fit” diffraction pattern was generated in order to estimate how much smaller the surface thickness can be such that one can still resolve five diffraction maxima. The range of amorphous surface thicknesses found from the calculated diffraction profile is 12-20 Å. This is in good agreement with complementary studies performed on the same crystal preparations.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1981.180190807
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  • 6
    Electronic Resource
    Electronic Resource
    Small-angle x-ray scattering studies of isothermally crystallized bulk polyethylene (1981)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1577-1591 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A set of isothermally melt-crystallized polyethylene samples was examined using small-angle x-ray scattering (SAXS). Time and temperature of crystallization were the variable parameters used to create the set of samples. Following background subtraction, desmearing, and application of the Lorentz factor to the raw SAXS data it is possible to see many orders of reflection. This suggests that much higher degrees of order are present in isothermally melt-crystallized samples than had previously been thought possible. A combination of SAXS and DSC data indicates that there is no evidence for isothermal thickening in these samples. This study, coupled with data obtained from PE single crystals, produced information concerning the extrapolation of single-crystal data to fit bulk systems. In addition, the equilibrium melting point T0m determined is somewhat lower than previously claimed. This study also suggests that the surface energy of the mature crystals is always lower than that of the nucleated state and/or the nucleation factor Kσen increases with decreasing supercooling.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1981.180191008
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  • 7
    Electronic Resource
    Electronic Resource
    Saxs determination of the maximum amorphous surface layer thickness of pom single crystals (1981)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1923-1924 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1981.180191210
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of polymorphism on the C—H stretching region of the infrared spectrum of polyethylene (1978)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 1253-1260 
    Details
    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
    URL: http://dx.doi.org/10.1002/pol.1978.180160708
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  • 9
    Electronic Resource
    Electronic Resource
    On the location of chain ends in polyethylene single crystals (1978)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 375-377 
    Details
    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
    URL: http://dx.doi.org/10.1002/pol.1978.180160217
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  • 10
    Electronic Resource
    Electronic Resource
    The heat of fusion of polymer crystals: Polyethylene crystals in suspension (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 63-71 
    Details
    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
    URL: http://dx.doi.org/10.1002/pol.1979.180170105
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