Abstract
The double-equation extended Pom-Pom (DXPP) constitutive model is used to study the macro and micro thermorheological behaviors of branched polymer melt. The energy equation is deduced based on a slip tensor. The flow model is constructed based on a weakly-compressible viscoelastic flow model combined with DXPP model, energy equation, and Tait state equation. A hybrid finite element method and finite volume method (FEM/FVM) are introduced to solve the above-mentioned model. The distributions of viscoelastic stress, temperature, backbone orientation, and backbone stretch are given in 4 : 1 planar contraction viscoelastic flows. The effect of Pom-Pom molecular parameters and a slip parameter on thermorheological behaviors is discussed. The numerical results show that the backbones are oriented along the direction of fluid flow in most areas and are spin-oriented state near the wall area with stronger shear of downstream channel. And the temperature alongy=-1is little higher in entropy elastic case than one in energy elastic case. Results demonstrate good agreement with those given in the literatures.
Highlights
Branched polymer becomes more and more concerned because of its unique structural characteristics and properties, its development is one of the fastest in macromolecular materials
Since the energy equation is deduced based on the slip tensor and the viscoelastic stress is calculated using a double-equation extended Pom-Pom (DXPP) model that can describe the backbone orientation and stretch of the polymer molecules, we will detail the solution of the energy equation and the DXPP model based on the nonstaggered grid under the framework of the FVM
The hybrid finite element method and finite volume method (FEM/FVM) method described above is used to solve the weakly-compressible flow model based on the DXPP constitutive model
Summary
Branched polymer becomes more and more concerned because of its unique structural characteristics and properties, its development is one of the fastest in macromolecular materials. In the Pom-Pom model, they simplified each branched molecule to a molecule with only two branched points at each end, and with a certain number of arms at each branched points This model is not completely consistent with the topological structure of branched molecules, but it is an important breakthrough in the field of viscoelastic constitutive models. Doubleequation XPP (DXPP) model can describe the microscopic orientation and stretch of backbone and study the influence of microscopic molecular parameters on the rheological behavior of branched polymers. Based on the characteristics of weakly-compressibility and high specific heat capacity of the polymer melt, the hybrid FEM/FVM method is used to solve the above model, and the macro and micro thermorheological properties of the branched polymer are discussed according to the numerical simulation results
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