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  • Polymer and Materials Science  (6)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 243-250 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The phase behavior and rheology of binary blends of polycarbonate (PC) and a liquid crystalline polymer (LCP) have been investigated. The thermotropic LCP employed was a semiflexible polyester synthesized by melt condensation of t-butylhydroquinone and 4,4′ dichloroformyl-α,ω-diphenoxyhexane. It shows a distinct nematic-to-isotropic transition in the pure state and in the blends. Results of DSC and optical microscopy indicate that the LCP is solubilized in the mixture for weight fractions of LCP less than about 0.05 and shows partial miscibility with PC over the rest of the composition range. The phase separation is considered to be driven by both isotropic and anisotropic interactions between constituent chains. Dynamic oscillatory measurements show that there is some interaction between the separate isotropic and anisotropic phases, with complex viscosities of the blends being intermediate between those of pure components and showing significant deviation from a logarithmic rule-of-mixtures. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 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 21 (1983), S. 2287-2298 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rheological properties of narrow-molecular-weight-distribution linear and star-branched polyisoprenes have been determined using both shearing and stretching deformations. At all strain rates studied the tensile stress measured under transient and steady-state conditions did not increase above the linear viscoelastic value. The absence of an enhanced tensile stress for the branched polymer is in contrast to what is observed for branched low-density polyethylene. An explanation for the difference is proposed. Additional remarks are made about the broad distribution of relaxation times observed for star-branched polyisoprenes and about the approach to steady state in constant-strain-rate and constant-stress tests.
    Additional Material: 7 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 20 (1982), S. 1249-1258 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Complex moduli are calculated for the lowest-order deviations from linearity of the stress in an oscillatory shear field. The calculations involve solution of an equation, recently proposed by Doi, which goes beyond the “independent alignment approximation” of the Doi-Edwards theory of polymer dynamics. The new equation incorporates various reptative motions of a polymer in the effective constraining tube induced by entanglements, viz. Brownian motion along the tube and the systematic motion in response to changes in the length of the tube accompanying affine deformation.
    Additional Material: 6 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 20 (1982), S. 83-98 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The limits of linear viscoelastic behavior of polystyrene solutions have been investigated by subjecting them to large-amplitude oscillatory strains, γ0. At strains less than one we find that the dynamic storage modulus G′(ω,γ0) and the dynamic loss modulus G″(ω,γ0) decrease quadratically with increasing strain. As a measure of the size of the linear viscoelastic region, we have determined the strain at which the moduli have fallen 5% below their zero-strain values. This strain, γNL, is found to be independent of frequency ω at high frequencies but to increase with decreasing frequency at low frequencies. Behavior of this type is in qualitative agreement with the recent constitutive equation developed by Doi and Edwards. More specifically, we find that the rate of decrease of the storage modulus with increasing strain is quite similar to that predicted by their theory, but that the rate of decrease of the loss modulus is much slower. Some possible approaches for improving the agreement with experimental results are suggested. In the course of our work an interesting hydrodynamic instability was observed. The nature of this instability and methods to avoid it are discussed.
    Additional Material: 9 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 12 (1974), S. 925-939 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The chemical and physical crosslink densities of irradiated polybutadiene were determined using a precise and consistent method. This method included the use of a statistical theory of crosslinking modified to include chain reactions and the use of Langley's theory for calculating the number of trapped chain entanglements. The number of crosslinks formed per unit radiation dose, G(X), was measured for a series of polybutadienes containing various isomeric forms of unsaturation. The physical crosslink density and the molecular weight between entanglements were determined from measurements of the compression modulus of swollen samples.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 13 (1992), S. 25-30 
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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