Bacterial and plant cellulose modification using ultrasound irradiation

This study indicates that controlled depolymerization of plant (PC) and bacterial (BC) celluloses can be achieved by employing suitable ultrasonication settings. Size exclusion chromatography results indicate that reduction in the molecular weight of the two polymers was accompanied by a parallel drop in the polydispersity index of PC and an unexpected increase in the said index of BC. X-ray diffraction patterns of the fractionated materials were found to be Cellulose II crystals whereas experimentation on microcrystalline cellulose unveiled the Cellulose I conformation. The crystallinity index revealed no obvious changes in PC as a function of the time of sonication whereas a major increase in the crystalline component was encountered for BC. Furthermore, thermal degradation using TGA and FTIR spectra suggest that the processes of dissolution and regeneration in cuprammonium hydroxide of PC and BC followed by ultrasonication do not affect the chemical fingerprints via oxidative reactions of the cellulosic materials. (c) 2009 Elsevier Ltd. All rights reserved.