The role of urea on dissolution of cellulose into alkali/urea aqueous solution was investigated by comparing characteristics of regenerated cellulose. To focus on the cellulose molecular properties, cellulose oligomer prepared by phosphoric acid hydrolysis (DP=7) was used as the cellulose sample. The cellulose oligomer was dissolved in (i) LiOH aqueous solution or (ii) LiOH/urea aqueous solution, and regenerated with 5wt% H2SO4. Although the regenerated celluloses had cellulose II type structure in both cases, the one from LiOH solution had a larger crystalline size than from LiOH/urea solution. This indicates that cellulose crystallization became slower with urea addition. Since the initial step of crystallization of cellulose II is a hydrophobic stacking by van der Waals force, this result implies that urea inhibits the hydrophobic interaction between cellulose molecules in the alkali/urea solution. Therefore, urea seems to inhibit re-coagulation of cellulose molecules and help the dispersion of cellulose molecules during dissolution process.

Role of urea on dissolution of cellulose into alkali/urea aqueous solution

243rd National Meeting (2012)

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