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Structure et propriétés des solutions et gel de cellulose-NaOH-Eau et leurs matériaux régénérés

Abstract : It has been reported that cellulose can be dissolved in aqueous sodium hydroxide solutions in a narrow range of NaOH concentrations (6-10%) and temperatures (-10°C/-4°C). Cellulose solutions obtained are not stable and gelation occurs with time and temperature increase. It has been also showed that the presence of additives, such as urea or zinc oxide, in solvent system improves the dissolution of cellulose fibres and the solution stability. In order to understand the structure of cellulose solutions in NaOH/water without or with additives, we first studied phase diagrams of solvents and then the influence of the addition of cellulose in these solvents on the DSC thermograms. We determined (i) the limit of cellulose dissolution in NaOH/water and in NaOH/urea/water and (ii) the nature of interactions occurring between cellulose chains, NaOH, urea, ZnO and water molecules. We also studied rheological properties of cellulose solutions in NaOH/water, NaOH/urea/water and NaOH/ZnO/water. The presence of additives delays gelation (in time and in temperature) but does not change its mechanism. Gelation of cellulose solutions is due to a decrease of solvent quality which favours the cellulose-cellulose interactions with the temperature increase. Finally, the study of mechanical properties, and especially the measurements of the stress at rupture of regenerated cellulose objects showed the great influence of gelation and regeneration parameters on the properties of the final products.
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https://pastel.archives-ouvertes.fr/pastel-00002229
Contributor : Ecole Mines Paristech <>
Submitted on : Tuesday, August 14, 2007 - 8:00:00 AM
Last modification on : Wednesday, October 14, 2020 - 4:02:44 AM
Long-term archiving on: : Thursday, September 30, 2010 - 7:49:34 PM

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  • HAL Id : pastel-00002229, version 1

Citation

Magali Egal. Structure et propriétés des solutions et gel de cellulose-NaOH-Eau et leurs matériaux régénérés. Sciences de l'ingénieur [physics]. École Nationale Supérieure des Mines de Paris, 2006. Français. ⟨pastel-00002229⟩

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