A failure of a class of K-BKZ equations based on principal stretches

Feigl, Kathleen; Öttinger, Hans Christian; Meißner, J.

doi:10.1007/bf00396174

Cited by 10 publications

(2 citation statements)

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“…Macromolecules, Vol. 30 1, Figures 5, 6, and 9) that the stress tensor σ for the model polymer melts can be written essentially as the sum of three parts where σ nn denotes the stress contribution from nearest neighbors within polymer chains (bond pushing/stretching or bond orientation or both) and σ simple is proportional to the stress σ simple , which is measured for a corresponding simple fluid by cutting all bonds within the system. A discussion of expression 8 is given in the next subsection.…”

Section: Computer Simulations Results and Discussionmentioning

confidence: 99%

“…Recent results have shown that simulations can be used to predict rheological behavior of real polymer melts, even if the simulation model does not contain specific chemical details 3,4,29,30 in accordance with predictions on self-similarity and universality in polymer systems. 31 To study the elongational flow behavior of model polymer melts, we have performed NEMD computer simulations at constant bead density and constant volume (NVT ensemble) in a cubic cell with periodic boundary conditions.…”

Section: The Microscopic Fene Chain Modelmentioning

confidence: 90%

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Polymer Melts under Uniaxial Elongational Flow: Stress−Optical Behavior from Experiments and Nonequilibrium Molecular Dynamics Computer Simulations

1997

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Tensile stress and birefringence in both real and model amorphous polymer melts have been measured during constant rate uniaxial elongational flow. We focus on investigations where deviations from the linear stress-optical behavior are pronounced. A rate-dependent contribution to the stress which is not directly related to the intramolecular conformations ("stress offset") is detected for both types of macromolecular fluids. Independent of the flow history, during relaxation a linear stressoptical behavior is revealed. Nonequilibrium molecular dynamics (NEMD) computer simulations on the multibead anharmonic spring model are shown to provide insight into the molecular mechanisms underlying the viscoelastic behavior: during relaxation the intermolecular interactions become dominant in correlation with linear stress-optical behavior; the stress offset is shown to be very similar to the stress arising in the corresponding simple fluid; the total stress can well be approximated by a sum of three parts which are based on single-particle and single-link distribution functions only; the yield point behavior at high elongation rates reflects the transition from affine to nonaffine motion of bonds and is understood without reference to strong inhomogeneities resulting from local plastic strain production [the chemical structure does not influence the qualitative behavior]; distinct microscopic stress contributions under elongation and subsequent relaxation such as inter-and intramolecular, attractive and repulsive, kinetic and potential contributions are resolved.

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Section: Computer Simulations Results and Discussionmentioning

confidence: 99%