Carboxymethylcellulose synthesis in organic media containing ethanol and/or acetone

• Published in: Journal of applied polymer science Vol. 67; no. 3; pp. 481 - 486
• Main Authors: Olaru, Niculae, Olaru, Liliana, Stoleriu, Aurel, Ţi˘mpu, Daniel
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 18.01.1998; Wiley
• Subjects: Applied sciences; calorimetry; carboxymethylcellulose; Cellulose and derivatives; cellulose crystallinity; Exact sciences and technology; kinetics; Natural polymers; Physicochemistry of polymers; x-ray diffraction; Solvent effect; Organic solvent; Cellulose alcali; Chemical modification; Mixed solvent; Amorphization; Carboxymethylation; Kinetics; Rate constant; Cotton; Experimental study; Heterogeneous reaction
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/(SICI)1097-4628(19980118)67:3<481::AID-APP11>3.0.CO;2-Z

A study of the carboxymethylation of wood pulp cellulose and cotton linters cellulose in different organic media, namely, ethanol, acetone, and ethanol‐acetone mixtures, is performed. Previously, the ethanol‐acetone 1 : 1 (w/w) mixture used as reaction medium was found to give a higher degree of substitution (DS) than the pure solvents separately. In the present work, the kinetic investigation of cellulose carboxymethylation was carried out in ethanol‐acetone 3 : 7 (w/w) mixture, as well as in acetone as reaction media, and the same synergistic effect of the solvents mixture was observed. The data suggested a pseudo‐first‐order kinetic behavior satisfactorily described by the following equation: ln(1.11 − DS) = −kt. The two reaction steps observed are related to the transformations of less ordered regions with higher reaction rate and more ordered regions with smaller reaction rates, respectively. A possible explanation for this behaviour is given, taking into account the different structural changes of cellulose crystallinity and accessibility produced by ethanol‐acetone 3 : 7 (w/w) mixture, ethanol, and acetone, as revealed by X‐ray diffraction and calorimetry determinations. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 481–486, 1998