(452c) Effect of Fines % on Ultrasonic Dewatering of Cellulose Nanofibrils

During the production of cellulose nanofibrils, mechanical fibrillation leads to the presence of different % of fines in the final product, defined as the fibrils under 200 um. Although the presence of fines has demonstrated mechanical advantages in composite materials, it also increases the water retention by the fibrils leading to increased dewatering time and energy. As addressing the high energy requirements during dewatering and drying of CNF is a high-priority target in the community, understanding the effect of underlying fibril dimensions on water retention becomes essential. In the present talk, we will discuss the effect of fines % of CNF on the dewatering efficiency of the ultrasonic dewatering technology and compare this with traditional dewatering/drying technique. Ultrasonic dewatering technique leverages the instabilities at the air-liquid interface generated by high frequency sound waves leading to the subsequent removal of water from the CNF slurry as cold mist. We will also discuss the redispersion of the subsequent dewatered samples and present an optical microscopy characterization technique to differentiate amongst various fines% in a fast and easy way. This microscopic analysis is also supported by nanoscale characterization through SEM.