Viscosity‐molecular weight relationship for cellulose solutions in either NMMO monohydrate or cuen |
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| Authors: | John Eckelt Anja Knopf Thomas Röder Hedda K Weber Herbert Sixta Bernhard A Wolf |
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| Affiliation: | 1. Institut für Physikalische Chemie der Johannes Gutenberg‐Universit?t Mainz and Materialwissenschaftliches Forschungszentrum der Universit?t Mainz, Welder‐Weg 13, D‐55099 Mainz, Germany;2. WEE‐Solve GmbH, Auf der Burg 6, D‐55130 Mainz, Germany;3. Lenzing AG, Department FE, A‐4860‐Lenzing, Austria;4. Kompetenzzentrum Holz GmbH (Wood K plus), A‐4021 Linz, Austria;5. Helsinki University of Technology, 02150 Espoo, Finland |
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| Abstract: | The intrinsic viscosities, η], of nine cellulose samples, with molar masses from 50 × 103 to 1 390 × 103 were determined in the solvents NMMO*H2O (N‐methyl morpholin N‐oxide hydrate) at 80°C and in cuen (copper II‐ethlenediamine) at 25°C. The evaluation of these results with respect to the Kuhn–Mark–Houwink relations shows that the data for NMMO*H2O fall on the usual straight line in the double logarithmic plots only for M ≤ 158 103; the corresponding η]/M relation reads log (η]/mL g−1) = –1.465 + 0.735 log M. Beyond that molar mass η] remains almost constant up to M ≈ 106 and increases again thereafter. In contrast to NMMO*H2O the cellulose solutions in cuen behave normal and the Kuhn–Mark–Houwink relation reads log (η]/mL g−1) = −1.185 + 0.735 log M. Possible reasons for the dissimilarities of the behavior of cellulose in these two solvents are being discussed. The comparison of three different methods for the determination of η] from viscosity measurements at different polymer concentrations, c, demonstrates the advantages of plotting the natural logarithm of the relative viscosities as a function of c. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 |
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| Keywords: | intrinsic viscosity cellulose NMMO hydrate cuen Kuhn– Mark– Houwink relation |
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