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Article Dans Une Revue Physical Review E Année : 2018

Shear-stress fluctuations and relaxation in polymer glasses

Résumé

We investigate by means of molecular dynamics simulation a coarse-grained polymer glass model focusing on (quasistatic and dynamical) shear-stress fluctuations as a function of temperature T and sampling time Δt. The linear response is characterized using (ensemble-averaged) expectation values of the contributions (time averaged for each shear plane) to the stress-fluctuation relation μ_{sf} for the shear modulus and the shear-stress relaxation modulus G(t). Using 100 independent configurations, we pay attention to the respective standard deviations. While the ensemble-averaged modulus μ_{sf}(T) decreases continuously with increasing T for all Δt sampled, its standard deviation δμ_{sf}(T) is nonmonotonic with a striking peak at the glass transition. The question of whether the shear modulus is continuous or has a jump singularity at the glass transition is thus ill posed. Confirming the effective time-translational invariance of our systems, the Δt dependence of μ_{sf} and related quantities can be understood using a weighted integral over G(t).

Dates et versions

hal-03549604 , version 1 (31-01-2022)

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I. Kriuchevskyi, J. P. Wittmer, H. Meyer, O. Benzerara, J. Baschnagel. Shear-stress fluctuations and relaxation in polymer glasses. Physical Review E , 2018, 97 (1), pp.012502. ⟨10.1103/PhysRevE.97.012502⟩. ⟨hal-03549604⟩
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