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  • Physics  (47)
  • Wiley-Blackwell  (47)
  • International Union of Crystallography
  • National Academy of Sciences
  • 1970-1974  (47)
  • 1950-1954
  • 1973  (47)
  • 1950
  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 457-465 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An approximate model is developed which relates the twisting seen in the spherulitic crystallization of many materials to surface stresses. Expressions are presented for the twist period as a function of the surface stress. These are compared with previous experimental data on polyethylene and data on hippuric acid obtained in the present investigation. In both cases the experimental data are in accord with the predictions of the model.
    Additional Material: 2 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 391-392 
    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.
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  • 3
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular core binding energies have been measured by ESCA for the homopolymers of ethylene and the fluoroethylenes. The data are interpreted in terms of semiempirical all-valence electron SCF MO calculations in the CNDO/2 formalism, in conjunction with the charge potential model. The results are used as a basis for interpreting the measured core binding energies of some Viton and Kel F type polymers. The routine application of ESCA to the determination of copolymer compositions is described.
    Additional Material: 7 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 1867-1879 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electroinitiated copolymerization of styrene and diethyl fumarate in methanol solvent with zinc bromide as electrolyte has been investigated at high current strengths (200-500 mA). Unlike the copolymerization behavior observed at lower current strengths (〈 200 mA), it is found that the cathodically produced copolymers deviate from a 1:1 composition and show a significant deficiency in styrene. The copolymer products can be separated into two well-defined fractions: a toluene-soluble fraction (normal copolymer) and a toluene-insoluble one (styrene-deficient copolymer). These deviations in copolymer composition from a 1:1 monomer ratio are attributed to the occurrence of cathodically induced electroreductive hydrolysis side reactions with diethyl fumarate leading to the formation of carboxylate or acid salt species. Reaction of these hydrolyzed species with diethyl fumarate results in the formation of fumarate-rich copolymers.
    Additional Material: 6 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 1555-1572 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Sorption, diffusion, swelling, and tensile stress relaxation measurements were made at room temperature (23°C) for the systems poly(n-butyl methacrylate) (PBMA) with liquid methanol and ethanol, and poly(methyl acrylate) (PMA) with liquid water. Stress relaxation curves for the fully swollen polymers could be superimposed approximately with those for the dry polymers by appropriate shifting along the long axes. For PMA-water the measured curve for stress relaxation with concurrent sorption could be predicted accurately by using a moving boundary theory with data measurements of stress relaxation of the unswollen and swollen polymer combined with sorption data. The modified moving boundary theory is generalized to include the effects of dimension changes through swelling and the larger effects of plasticization associated with sorption of liquids. This improved theory accurately predicts measured curves of stress relaxation with concurrent sorption for the PBMA-alcohol systems from individual stress relaxation, sorption, diffusion and swelling data. The general approach should be applicable to other amorphous polymer-liquid swelling agent systems. The anisotropic nature of swelling of polymer films and its effect on calculated diffusion coefficients are discussed briefly.
    Additional Material: 9 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 1949-1961 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Cast samples of a phenol-formaldehyde polymer with a crack of length defined by a metallic foil inclusion were fractured in tension. The stress at fracture was inversely proportional to the square root of the crack length, in agreement with the Griffith equation for brittle fracture. The behavior did not conform to the Griffith equation with respect to the experimental value of surface free energy, which was several orders of magnitude higher than a theoretically calculated value. However, as the temperature of tensile testing was raised, the experimental value did approach the calculated value. Consistently the appearance of the fracture surface was observed to change from one showing evidence of plastic deformation at room temperature to a featureless appearance, characteristic of brittle fracture, at higher temperatures.
    Additional Material: 9 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 2039-2055 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The fracture surface of notched impact specimens of polycarbonate tested in the range 130°C to -196°C have been studied by use of optical microscopy and scanning electron microscopy. The morphological features associated with the initiation and propagation of fracture have been determined and interpreted in terms of the processes which occur in association with fracture, notably crazing. The fracture processes are similar to those observed in poly(methyl methacrylate) and polystyrene. The transition from ductile to brittle fracture is attributed to the case of crazing relative to shear yielding.
    Additional Material: 13 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 2467-2482 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Rouse equations for the dissipative motion of long-chain molecules are reformulated in terms of coupled Langevin equations. While in the conventional Rouse model the random forces acting on each bead are supposed to be uncorrelated, the calculation given here admits of any correlation between the forces. By virtue of the second fluctuation dissipation theorem this corresponds to an added friction factor, called the “internal viscosity” in agreement with earlier work of Kuhn and Kuhn, Cerf, and of Peterlin. In the mode decomposition, this added friction factor happens to be an even function of the mode frequency. From this general model it is possible to compute formally the mean-square displacement function. It takes a simple form if one assumes that forces are correlated only on adjacent beads and that their correlation functions are δ functions. The results of the calculation are best displayed in the Fourier transform of the meansquare displacement, which is directly related to the neutron incoherent scattering cross section. It is seen that the presence of internal viscosity modifies the behavior of the chain for a time scale of the order of the relaxation time of the elementary segment.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 2315-2328 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The depolarization thermocurrent (DTC) method gives the dependence of the dielectric relaxation time on temperature. It has been used for investigations of relaxations obeying an Arrhenius-like law in crystalline polymers. The analysis of this method shows it is possible to study mechanisms described by the Williams-Landel-Ferry (WLF) equation. The critical temperature appearing in the free-volume theory of Cohen and Turnbull and also in the statistical thermodynamic theory of Adam and Gibbs can then be measured with good accuracy. The thermal coefficient of expansion of the free-volume and the WLF coefficient for any reference temperature can also be obtained. Since analysis of the experimental DTC spectrum is particularly simple, this method seems to be a very useful tool for examination of relaxation transitions in amorphous polymers. As an example, results obtained for poly(methyl methacrylate) are presented; they are consistent with published data.
    Additional Material: 7 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 1201-1218 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The elastic displacement of an axially stressed chain within crystalline surroundings, which was first treated by Chevychelov, is reexamined. We compare the results obtained for homogeneously distributed masses with that for discrete atoms, considering the nonuniformity of the potential of a crystal containing hydrogen bonds. In polyethylene and polyamide the maximum mechanical excitation of a chain penetrates into the crystal a distance of 15 to 20 chain atoms. The effect of the relative position of the crystal boundary on the stress-strain field was studied and the energy of defects calculated.
    Additional Material: 5 Ill.
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