Dynamical heterogeneities and mechanical non-linearities: Modeling the onset of plasticity in polymer in the glass transition

Abstract : In this paper we focus on the role of dynamical heterogeneities on the non-linear response of polymers in the glass transition domain. We start from a simple coarse-grained model that assumes a random distribution of the initial local relaxation times and that quantitatively describes the linear viscoelasticity of a polymer in the glass transition regime. We extend this model to non-linear mechanics assuming a local Eyring stress dependence of the relaxation times. Implementing the model in a finite element mechanics code, we derive the mechanical properties and the local mechanical fields at the beginning of the non-linear regime. The model predicts a narrowing of distribution of relaxation times and the storage of a part of the mechanical energy --internal stress-- transferred to the material during stretching in this temperature range. We show that the stress field is not spatially correlated under and after loading and follows a Gaussian distribution. In addition the strain field exhibits shear bands, but the strain distribution is narrow. Hence, most of the mechanical quantities can be calculated analytically, in a very good approximation, with the simple assumption that the strain rate is constant.
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https://hal-mines-paristech.archives-ouvertes.fr/hal-01700965
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Soumis le : lundi 5 février 2018 - 14:31:26
Dernière modification le : jeudi 4 juillet 2019 - 11:00:07

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R.J. Masurel, P. Gelineau, F. Lequeux, Sabine Cantournet, Hélène Montes. Dynamical heterogeneities and mechanical non-linearities: Modeling the onset of plasticity in polymer in the glass transition. European Physical Journal E: Soft matter and biological physics, EDP Sciences: EPJ, 2017, 40, pp.116 ⟨10.1140/epje/i2017-11606-5⟩. ⟨hal-01700965⟩

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