Cellulose Chemistry and Technology

Title
Investigations on solution of cellulose in complex phosphoric acid solvent and its stability
Authors
RUI XIONG FAXUE LI JIANYONG YU PANPAN HU ZHAOFENG LIU and YOU-LO HSIEH

Received May 23, 2012
Published Volume 47 Issue 3-4 March-April
Keywords cellulose, complex phosphoric acid solvent, dissolution behavior, liquid crystalline solution, dissolution power, stability

Abstract
Cotton cellulose pulp was dissolved in phosphoric acid (PA) complex solvent and properties of the subsequent solution were discussed. Equivalent P2O5 concentration was calculated to clarify theoretically the compositions in the dissolution media. The resulting dark yellow solution confirmed Boerstoel’s suggestion that cellulose must be degraded when temperature of solution is higher than 42 °C. Cholesteric lyotropic liquid crystalline solutions prepared at 72%, 73% and 74% P2O5 were observed. The clearing temperature of corresponding solutions was determined by hot-stage polar light microscope (PLM). The complex PA solvent prepared with P2O5 concentration of 73% had stronger dissolution power than those prepared with other concentrations. Phosphorus molar ratio data showed that tetraphosphoric acid (TPA) can result in indirect dissolution of cellulose, once P2O5 concentration of the complex solvent reaches 74%. Solution stability through DP analysis of cellulose solutions revealed significant results on the intrinsic sensitivity of this complex solvent to cellulose.