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Article Dans Une Revue Proceedings of the National Academy of Sciences of the United States of America Année : 2018

Cellulose crystals plastify by localized shear

Résumé

Cellulose microfibrils are the principal structural building blocks of wood and plants. Their crystalline domains provide outstanding mechanical properties. Cellulose microfibrils have thus a remarkable potential as eco-friendly fibrous reinforcements for structural engineered materials. However, the elastoplastic properties of cellulose crystals remain poorly understood. Here, we use atomistic simulations to determine the plastic shear resistance of cellulose crystals and analyze the underpinning atomic deformation mechanisms. In particular, we demonstrate how the complex and adaptable atomic structure of crystalline cellulose controls its anisotropic elastoplastic behavior. For perfect crystals, we show that shear occurs through localized bands along with noticeable dilatancy. Depending on the shear direction, not only noncovalent interactions between cellulose chains but also local deformations, translations, and rotations of the cellulose macromolecules contribute to the response of the crystal. We also reveal the marked effect of crystalline defects like dislocations, which decrease both the yield strength and the dilatancy, in a way analogous to that of metallic crystals.

Dates et versions

hal-01828806 , version 1 (03-07-2018)

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Citer

Gergely Molnar, David Rodney, Florian Martoïa, Pierre J.J. Dumont, Yoshiharu Nishiyama, et al.. Cellulose crystals plastify by localized shear. Proceedings of the National Academy of Sciences of the United States of America, 2018, 115 (28), pp.7260-7265. ⟨10.1073/pnas.1800098115⟩. ⟨hal-01828806⟩
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