Moisture uptake in native cellulose – the roles of different hydrogen bonds: a dynamic FT-IR study using Deuterium exchange |
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Authors: | Karin Hofstetter Barbara Hinterstoisser Lennart Salmén |
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Institution: | 1. Institute for Mechanics of Materials and Structures, Vienna University of Technology (TU Wien), Karlsplatz 13/202, 1040, Vienna, Austria 2. Department of Materials Science and Process Engineering, BOKU – University of Natural Resources and Applied Life Science Vienna, Peter Jordan Stra?e 82, 1190, Vienna, Austria 3. STFI-Packforsk AB, Box 5604, SE-114 86, Stockholm, Sweden
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Abstract: | This paper aims at a better understanding of the interaction between cellulose and moisture. In particular, the role of different
hydrogen bonds in moisture uptake is investigated. Dynamic Fourier transform infrared spectroscopy (FT-IR) has been used in
combination with deuterium exchange, which permits the labelling of cellulose domains with different accessibilities.
The static spectra indicate a marked exchange of deuterium for the O2–H⋯O6 bonds, but only a limited exchange for the O3–H⋯O5
bonds. In the dynamic FT-IR spectra, deuteration gives rise to the growth of a broad band at wavenumbers around 2500 cm−1. The rather unstructured appearance of the band suggests that deuteration is occurring only on the surface of the cellulose
crystallites, i.e. in more or less non-load-carrying parts. This is corroborated by the lack of split peaks related to OD
bonds in this band. In agreement with these observations, the split peak related to O3–H⋯O5 bonds and assigned to the load
carrying cellulose structure increases during both H2O and D2O moisture conditioning, indicating a shift of the load transfer towards the backbone of the cellulose structure. |
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Keywords: | Accessibility and reactivity Cellulose Deuterium exchange Dynamic FT-IR Hydroxyl groups |
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