Rapid dissolution of cellulose in LiOH/urea and NaOH/urea aqueous solutions.
Rapid dissolution of cellulose in LiOH/urea and NaOH/urea aqueous solutions was studied systematically. The dissolution behavior and solubility of cellulose were evaluated by using (13)C NMR, optical microscopy, wide-angle X-ray diffraction (WAXD), FT-IR spectroscopy, DSC, and viscometry. The experiment results revealed that cellulose having viscosity-average molecular weight ((overline) M eta) of 11.4 x 104 and 37.2 x 104 could be dissolved, respectively, in 7% NaOH/12% urea and 4.2% LiOH/12% urea aqueous solutions pre-cooled to -10 degrees C within 2 min, whereas all of them could not be dissolved in KOH/urea aqueous solution. The dissolution power of the solvent systems was in the order of LiOH/urea > NaOH/urea >> KOH/urea aqueous solution. The results from DSC and (13)C NMR indicated that LiOH/urea and NaOH/urea aqueous solutions as non-derivatizing solvents broke the intra- and inter-molecular hydrogen bonding of cellulose and prevented the approach toward each other of the cellulose molecules, leading to the good dispersion of cellulose to form an actual solution.
Cai
Jie
J
Department of Chemistry, Wuhan University, Wuhan 430072, China.
Zhang
Lina
L
D002482:Cellulose / Q000737:chemistry*; D018020:Lithium Compounds; D009682:Magnetic Resonance Spectroscopy; D012972:Sodium Hydroxide; D012995:Solubility; D012997:Solvents; D014508:Urea
D018020:Lithium Compounds; D012997:Solvents; D012972:Sodium Hydroxide; D014508:Urea; D002482:Cellulose; C028467:lithium hydroxide