The effect of water on cellulose solutions in DMAc/LiCl |
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Authors: | Thomas Röder Antje Potthast Thomas Rosenau Paul Kosmsa Thomas Baldinger Bernd Morgenstern Otto Glatter |
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Institution: | 1. University of Agricultural Sciences Vienna, Christian Doppler Laboratory, Muthgasse 18, A-1190 Vienna, Austria
Lenzing AG, A-4860 Lenzing, Austria;2. University of Agricultural Sciences Vienna, Christian Doppler Laboratory, Muthgasse 18, A-1190 Vienna, Austria;3. Lenzing AG, A-4860 Lenzing, Austria;4. FILK GmbH, Postfach 1144, D-09581 Freiberg, Germany;5. University of Graz, Department of Chemistry, Heinrichstrasse 28, A-8010 Graz, Austria |
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Abstract: | The solution state of cellulose in the system N,N-dimethylacetamide/lithium chloride (DMAc/LiCl) depends on various factors such as cellulose concentration, provenience (cotton, hardwood, softwood) and chemical history (pulping, pretreatment, bleaching) of cellulose, LiCl concentration, activation method, dissolution conditions (time, shaking), and water content. In particular the influencing of the latter has been intensively investigated in our present studies. Working in anhydrous conditions is not practicable for routine size exclusion chromatography (SEC) analysis. Especially in solutions diluted to SEC levels (0.9 wt% LiCl), an aggregation induced by water was observed. Depending on the time of dissolution and on the amount of water, changes in the solution state were observed. In some cases the amount of aggregates increases within a few minutes. This is reflected by a time-dependent increase in the scattering intensity and quantitatively proved by an increase in the aggregation peak in the calculated intensity distributions. With less soluble pulps, traces of water (lower than 0.01 M) can already suffice to induce and promote aggregation. To disturb a “good” stock solution, the concentration of water must be higher than 0.05 M. The aggregates formed correspond to the model of the fringed micelle. |
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