Journal ArticleDOI
Constitutive equations from Gaussian slip-link network theories in polymer melt rheology
Manfred H. Wagner,J. Schaeffer +1 more
TLDR
In this paper, the constitutive equations of temporary slip-link networks are derived, and 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.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.read more
Citations
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Journal ArticleDOI
Constitutive equations for polymeric liquids
R. Byron Bird,John M. Wiest +1 more
TL;DR: The origins, uses and evaluation of constitutive equations for the stress tensor of polymeric liquids are discussed in this paper, where the authors also discuss the use of the constitutive equation for the tensor tensor.
Journal ArticleDOI
Rheology and structural changes of polymer melts via nonequilibrium molecular dynamics
TL;DR: In this article, nonequilibrium molecular dynamics computer simulations of a planar Couette flow are presented for the multibead anharmonic-spring model, where the finitely extensible nonlinear elastic force law is used to connect the up to 100 beads of a chain molecule.
Journal ArticleDOI
The molecular stress function model for polydisperse polymer melts with dissipative convective constraint release
TL;DR: In this article, a new dissipative constraint release model was proposed for tube deformation in polymer melts, which is based on a dissipative convective constraint release process and a strain-dependent evolution equation for the molecular stress.
Journal ArticleDOI
Quantitative assessment of strain hardening of low-density polyethylene melts by the molecular stress function model
Abstract: The elongational viscosity of three tubular and five autoclave low-density polyethylene (LDPE) melts is analyzed, and quantitative comparison of the strain-hardening characteristics is made by using the molecular stress function model. This is based on a new strain-energy function, which assumes that the total strain energy of a branched section of a macromolecule is given by the addition of the strain energies of the individual chain segments contained in this section. The model employs only two nonlinear material parameters: one parameter describes the average number of crosslinked chain segments, which occupy the same tube section, and determines the slope of the elongational viscosity after inception of strain hardening. The second parameter indicates the maximum relative stretch of the chain segments and determines the steady-state (plateau) value of the elongational viscosity. Both parameters depend on the complex branching topology of LDPE melts. While quantitative relationships between branching structure and the two nonlinear parameters are not yet available, the results of this comparison seem to indicate that the more tree-like structure of autoclave LDPE leads to a higher density of crosslinked chain segments in the same tube section than in the case of LDPE polymerized in tubular reactors.
Journal ArticleDOI
Quantitative analysis of melt elongational behavior of LLDPE/LDPE blends
TL;DR: In this paper, the authors analyzed the shear and elongational data of linear (LLDPE) and branched (LDPE)-polyethylene polyethylene blends and showed that the strain hardening behavior of LLDPE/LDPEs is completely determined by the LDPE component.
References
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Journal ArticleDOI
A New Approach to the Theory of Relaxing Polymeric Media
M. S. Green,A. V. Tobolsky +1 more
TL;DR: In this article, the second law of thermodynamics is used to define dissipation of energy at constant temperature and explicit expressions for dissipation energy for any strain history are obtained, inasmuch as relaxation during straining causes an essential reorganization of structure which is in fact the cause of dissipation.
Journal ArticleDOI
Dynamics of concentrated polymer systems. Part 2.—Molecular motion under flow
Masao Doi,Sam F. Edwards +1 more
TL;DR: In this paper, the primitive chain model presented in Part 1 is extended to the case in which the system is macroscopically deformed, and the molecular expression of the stress due to primitive chain is given, and stress relaxation after a sudden deformation is calculated as an example.
Journal ArticleDOI
A network theory of flow birefringence and stress in concentrated polymer solutions
Journal ArticleDOI
Analysis of time-dependent non-linear stress-growth data for shear and elongational flow of a low-density branched polyethylene melt
TL;DR: In this paper, a single integral constitutive equation is presented, which gives a reasonable description of the non-linear shear and elongational behavior of a low-density branched polyethylene melt at constant strain rate observed by Meissner.
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Dynamics of concentrated polymer systems. Part 4.—Rheological properties
Masao Doi,Sam F. Edwards +1 more