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  • 1
    Electronic Resource
    Electronic Resource
    Analysis of Small-Angle Neutron Scattering Data on Poly(dimethylsiloxane) Network Unfolding (1994)
    s.l. : American Chemical Society
    Macromolecules 27 (1994), S. 5223-5226 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00096a056
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Assessment of nonlinear strain measures for extensional and shearing flows of polymer melts (1994)
    Springer
    Rheologica acta 33 (1994), S. 506-516 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00366335
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  • 3
    Electronic Resource
    Electronic Resource
    The nonlinear strain measure of polyisobutylene melt in general biaxial flow and its comparison to the Doi-Edwards model (1990)
    Springer
    Rheologica acta 29 (1990), S. 594-603 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01329306
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  • 4
    Electronic Resource
    Electronic Resource
    Constitutive equations from Gaussian slip-link network theories in polymer melt rheology (1992)
    Springer
    Rheologica acta 31 (1992), S. 22-31 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00396464
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  • 5
    Electronic Resource
    Electronic Resource
    Network disentanglement and time-dependent flow behaviour of polymer meltsHerrn Prof. Dr. H. Batzer zum 60. Geburtstag gewidmet (1980)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 1533-1550 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: For small strains Lodge's rubberlike-liquid theory is a valid description of the rheological behaviour of polymer melts, but at higher strains the theory fails: The phenomenon of shear thinning which is characteristic for the shear flow of nearly all polymer liquids is not explained, and in elongation the deviation of the experimental data from the predictions of Lodge's theory reflect also a flow thinning, and not a strain hardening in spite of the pronounced S-shape of the stress-strain diagrams. Comparing the measured stress growth and stress relaxation data with the predictions of the theory, it must be concluded that the temporary physical network structure of the polymer melt is destroyed increasingly with the magnitude of the deformation. Hence, the number of entanglements decreases with increasing strain. For simple shear and uniaxial extension of a well-defined polyethylene melt the strain dependence of the relative entanglement density is discussed. The irreversibility of the disentanglement process of the network is considered.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1980.021810716
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    Paper (German National Licenses)
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