Swelling and dissolution of cellulose in amine oxide/water systems
The swelling behavior and the dissolution process of various cellulosic fibers, both native and regenerated, in N-methylmorpholine N-oxide (MMNO), dimethylethanolamine N-oxide (DMEAO), and mixtures thereof were studied in the presence of various amounts of water. The principal tools in this investigation were optical microscopy and wide-angle X-ray scattering (WAXS). The two amine oxides could either dissolve or only swell cellulose, depending on the water concentration, which was found to be of critical importance. Three domains of water concentration were found important. When only a few percent water was present, cellulose fibers, such as ramie, cotton, rayon, etc., dissolved readily without noticeable swelling in the amine oxide/water system brought above its melting point. At a relatively high water concentration (e.g., 18% w/w for MMNO), the cellulose fibers exhibited an extensive swelling (up to sevenfold increase in the fiber diameter) but no dissolution. In that case, the removal of the swelling agent showed that the initial native cellulose fibers were converted into an unoriented cellulose II structure. With still greater water content (e.g., 20% and more for MMNO or 15% for DMEAO), only partial swelling was observed, and the native cellulose fibers recovered their initial oriented cellulose I structure after removal of the swelling medium. X-ray investigations provided no evidence forthe formation of cellulose/solvent complexes in the swollen fibers. A relatively large decrease of the cellulose I (110) reflection was found in the WAXS patterns of the gels. This is interpreted as due to a preferential cleavage of the cellulose crystals along the corresponding plane when the cellulose fibers are exposed to the swelling forces of the amine oxide/water systems. 29 references, 13 figures, 1 table.
- Research Organization:
- Centre de Recherches sur les Macromolecules Vegetales, Grenoble, France
- OSTI ID:
- 6971429
- Report Number(s):
- CONF-8205234-Vol.1
- Journal Information:
- J. Appl. Polym. Sci.: Appl. Polym. Symp.; (United States), Journal Name: J. Appl. Polym. Sci.: Appl. Polym. Symp.; (United States); ISSN JPSSD
- Country of Publication:
- United States
- Language:
- English
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AMINES
CARBOHYDRATES
CELLULOSE
COHERENT SCATTERING
COTTON
DIAGRAMS
DIFFRACTION
DISSOLUTION
HYDROGEN COMPOUNDS
MICROSCOPY
OPTICAL MICROSCOPY
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXYGEN COMPOUNDS
PHASE DIAGRAMS
PLANTS
POLYSACCHARIDES
QUANTITY RATIO
RAYON
SACCHARIDES
SCATTERING
SWELLING
WATER
WOOD
X-RAY DIFFRACTION