Ultrasonic depolymerization of aqueous carboxymethylcellulose

Prolonged exposure of solutions of macromolecules to high-energy ultrasonic waves produces a permanent reduction in viscosity, However, the exact mechanism by which degradation occurs is still open to discussion. According to this study hydrodynamic forces played the primary role in degradation process. This study showed that there is an optimal carboxymethylcellulose (CMC) concentration to the most efficient degradation. Ultrasound degraded preferentially large CMC molecules and cleavage took place roughly at the centre of the CMC molecules. Degradation of CMC did not proceed below a certain molecular mass. During ultrasonic degradation the molecular mass distribution narrowed. For any polymer degradation process to become acceptable to industry, it is important to be able to specify the sonication conditions to produce a particular relative molecular mass distribution. (C) 2003 Elsevier B.V. All rights reserved.