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Influence of hydrogen bonds on glass transition and dielectric relaxations of cellulose

Roig, Frédéric and Dantras, Eric and Dandurand, Jany and Lacabanne, Colette Influence of hydrogen bonds on glass transition and dielectric relaxations of cellulose. (2011) Journal of Physics D: Applied Physics, vol. 44 (n° 4). ISSN 0022-3727

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Official URL: http://dx.doi.org/10.1088/0022-3727/44/4/045403

Abstract

The molecular dynamics in hydrated cellulose has been investigated by a combination of thermal analyses and dielectric spectroscopy. Differential scanning calorimetry shows the dependence upon hydration of the glass transition temperature Tg. A physical ageing phenomenon has been observed. At the molecular scale, bound water is hydrogen bonded to polar sites of cellulose macromolecules. At the macroscopic scale, water molecules play the role of a plasticizer for cellulose lowering its Tg. Dynamic dielectric spectroscopy combined with thermostimulated currents have allowed us to follow more localized molecular mobility. The β relaxation mode is characterized by activation entropies that vanish for higher water contents indicating molecular mobility localization. It is plasticized by water like the glass transition. This analogy is explained by a common origin of both mechanisms: the mobility of the cellulose backbone. The evolution of the γ mode upon hydration follows an anti-compensation law. Water acts as an anti-plasticizer in a hydrogen bonded network.

Item Type:Article
Additional Information:Thanks to Institute of Physics editor. The definitive version is available at http://iopscience.iop.org/ The original PDF of the article can be found at Thermochimica Acta website : http://iopscience.iop.org/0022-3727/44/4/045403
Audience (journal):International peer-reviewed journal
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Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
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Deposited By: Leila Abdelouhab

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