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arXiv · 2610.02884

Orientational origin of nonlinear shear rheology in unentangled polymer melts

Souta Miyamoto·Takeshi Sato·John J. Molina·Takashi Taniguchi
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Abstract

Universal rheological properties of unentangled polymer melts are investigated through the stretch-orientation decomposition of polymer dynamics. By externalizing stretch from the explicit state of each Rouse mode, we construct a constitutive model with orientational kinetics that preserves the Rouse relaxation spectrum. The resulting model yields the observed steady-shear scalings of the shear viscosity and first normal-stress coefficient, predicts a finite second normal-stress coefficient, and approximately reproduces the Cox-Merz and Gleissle-Osaki rules. The derived steady-oscillatory shear correspondence further identifies an elastic contribution, associated with the first normal stress difference, that is absent from the conventional Cox-Merz rule.

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Souta Miyamoto, Takeshi Sato, John J. Molina, Takashi Taniguchi. 2026-10-02. Orientational origin of nonlinear shear rheology in unentangled polymer melts. https://arxiv.org/abs/2610.02884

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