Modeling nonlinear rheology of polydisperse polymer melts

• Autorzy: Wagner M. H.
• Języki publikacji: EN

Abstrakty

EN

Melt rheology of polydisperse polymers is reviewed with special emphasis on the separation of effects of chain orientation and chain stretch, as described consistently by the Molecular Stress Function (MSF) theory. Based on energy balance considerations, first the Free Energy of a tube segment with a strain-dependent tube diameter is established, and it is demonstrated that the molecular stress is a function of the orientational free energy under these conditions. Then constraint release is introduced as a dissipative process, which modifies the energy balance of tube deformation, and leads to a strain-dependent evolution equation for the molecular stress function. For simple shear and extensional flows, the predictions of the MSF model consisting of a history integral for the stress tensor and a differential evolution equation for the molecular stress function with only one (extensional flows) or two (shear flow) nonlinear material parameters, are in excellent agreement with experimental data of HDPE, LDPE, LLDPE, PS, and PP melts. The concept of a strain-dependent tube diameter, which decreases with increasing deformation, explains consistently the strain hardening of linear as well as of long-chain branched polymer melts.

Słowa kluczowe

EN

linear polymer melts; long-chain branched polymer melts; molecular stress function theory; orientation; stretch strain energy function; extensional flow; shear flow

PL

polimery; reologia

• Wydawca: Oficyna Wydawnicza Uniwersytetu Zielonogórskiego
• Czasopismo: International Journal of Applied Mechanics and Engineering
• Rocznik: 2006
• Tom: Vol. 11, no 2
• Strony: 255--267
• Opis fizyczny: Bibliogr. 15 poz., rys., wykr.

Twórcy

autor

Wagner M. H.

• Polymertechnik/Polymerphysik, TU Berlin Fasanenstr. 90, D-10623 Berlin, GERMANY,

Bibliografia

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• Wagner M.H., Hepperle J. and Münstedt H. (2004): Relating molecular structure of model branched polystyrene melts to strain-hardening by molecular stress function theory. - J. Rheol., vol.48, pp.489-503.
• Wagner M.H., Rubio P. and Bastian H. (2001): The molecular stress function model for polydisperse polymer melts with dissipative convective constraint release. - J. Rheol., vol.45, pp.1387-1412.
• Wagner M.H., Yamaguchi M. and Takahashi M. (2003): Quantitative assessment of strain-hardening of LDPE melts by MSF model. - J. Rheol., vol.47, pp.779-793.