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  • Physics  (4)
  • *Artificial Organs
  • 1975-1979  (4)
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Deformation and microstructure of extended-chain polydiacetylene crystals (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1871-1879 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mechanical properties (Young's modulus, ultimate tensile strength, deformation processes) of extended-chain polydiacetylene crystals are investigated. The properties observed are similar to those of metal and ceramic whiskers. The elastic modulus is strain-dependent and the ultimate tensile strength increases with decreasing crystal size. The maximum tensile strength observed was 1700 Nmm-2. The ultimate tensile strength seems to be controlled by the presence of a small number of defects near the surface at which fracture nucleates. Irreversible deformation of the crystals was observed to occur by crack propagation normal and parallel to the direction of the macromolecules. The observed mechanical behavior corresponds to exceptionally high per-chain properties. The per-chain modulus obtained for these crystals is nearly as high as that of diamond. A chain-aligned polyethylene fiber with the same per-chain mechanical properties would have an ultimate strength as high as 0.9 × 104 Nmm-2.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.180131002
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  • 2
    Electronic Resource
    Electronic Resource
    Comments on the optical properties of fully conjugated polymers: Analogy between polyenes and polydiacetylenes (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 2037-2045 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The similarity of the π-electron backbones of the polyenes and the polydiacetylenes suggests an analogy between these two fully conjugated, linear polymers. The extent of the analogy is discussed through the examination of a series of model compounds: the polyenes and the polyenynes. The optical band gaps and the polarizabilities of polyenynes are compared to those of the polyenes and to the predictions of a modified free-electron model. It is concluded that the chain-dependent electronic properties of the polyenes may be extrapolated with some confidence to the polydiacetylenes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.180141109
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  • 3
    Electronic Resource
    Electronic Resource
    The nature and origin of structural defects in polymeric sulfur nitride (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 2019-2035 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Defect structures in (SN)x crystals obtained by solid-state polymerization are so numerous and varied that they are likely to conceal inherent property aspects of the defect-free polymer. In addition to frequent macroscopic twinning, three different kinds of defect sites are observed. These sites are related to the disruption of molecular orientational order about the chain axis direction and the sequencing of chain types in the periodic phase. The origin of these defects is explained by the nonuniqueness of solid-state polymerization and recrystallization processes, which transform the initial dimer phase to the final polymer phase. The orientational relationship between the dimer and polymer phase is predicted from the observed twinning mode and the structural relationship between these phases. The change from dimer phase (at zero and at intermediate conversions involving solid solution formation) to polymer phase can be described by a shear transformation on the (001) dimer plane. This observation suggests an analogy with known martensitic reactions and a method for improving the perfection of (SN)x.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.180141108
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of the ladder polymerization of a crystalline cyclotetradiyne monomer (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 655-662 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polymerization of the cyclic tetradiyne monomer, [—(CH2) 2—C≡C—C≡C—(CH2)2—]4, containing interstitial chloroform has been investigated using Raman and Fourier-transform infrared spectroscopy and x-ray diffraction techniques. A loss of crystallographic register between chains occurs during the polymerization reaction, although crystalline order in the chain-axis projection is retained. These studies indicate that 50 Mrad of 60Co γ-ray irradiation produces 1,4-addition polymerization at most of the diacetylene functionalities. Unreacted diacetylene groups are present primarily, although not completely, in soluble oligomeric material. Infrared spectroscopy indicates that this low molecular weight material has a butatriene (cumulene) backbone structure rather than the acetylenic structure of the insoluble polymer.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1979.180170408
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