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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 27 (1994), S. 5223-5226 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Rheologica acta 29 (1990), S. 594-603 
    ISSN: 1435-1528
    Keywords: Doi-Edwards theory ; nonlinear viscoelasticity ; general extensional flow ; polyisobutylene (PIB)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The nonlinear strain measure of a polyisobutylene (PIB) melt as determined by analysis of uniaxial, planar, ellipsoidal, and equibiaxial extensions is compared to the predictions of the molecular model of Doi and Edwards. It is found that the universal strain function of the Doi-Edwards model is unable to predict the nonlinear behavior of this polymer melt in general extensional flow. The qualitative agreement between predictions and experimental data for the strain dependence of shear stress and first normal stress difference in shear flow that was considered as powerful evidence for the correctness of the Doi-Edwards model seems to be accidental. The exaggerated strain dependence of the model suggests a need to reconsider the assumptions concerning the chain retraction process.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Rheologica acta 31 (1992), S. 22-31 
    ISSN: 1435-1528
    Keywords: Polymer melts ; constitution equations ; molecular theory ; chain slip ; chain disentanglement ; extensional flow with step change in flow direction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Allowing for flow-dependent slip in the junctions of a temporary junction network, we derive the constitutive equations of temporary slip-link networks. The stress tensor is determined by three material functions, namely, the time-dependent linear-viscoelastic memory function, and two strain-dependent functions describing slip and disentanglement of network strands. Slip and disentanglement are related via a mass balance for network strands. By specifying slip and disentanglement, the constitutive equations of Lodge, Wagner, Doi-Edwards, and Marrucci are shown to be special temporary slip-link constitutive equations. To demonstrate the predictive power of temporary slip-link network theories, we compare predictions and extensional flow data with step change in flow direction.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Rheologica acta 33 (1994), S. 506-516 
    ISSN: 1435-1528
    Keywords: Strain measure ; damping function ; extensional flow ; transversely isotropic flow ; planar flow ; shear flow ; Doi-Edwards model ; molecular stress function ; classification of extensional flows ; planarity index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract From stress-strain experiments in extensional and shearing flows, nonlinear strain measures and effective damping functions are derived for a polyisobutylene melt. The strain measures determined in planar extensional flow and in simple shear flow coincide. Experimental results are compared with predictions of two molecular theories, the Doi-Edwards model and the molecular stress function approach of Wagner and Schaeffer. Discrepancies between theories and experiment lead to a reconsideration of the classification of extensional flows. The symmetry of the flow field is identified and quantified as an important parameter influencing the strain measure, and a unifying strain measure for general extensional and shearing flows of polymer melts is presented.
    Type of Medium: Electronic Resource
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