Increased production of aligned cellulose nanofibrils using microfluidic mixture chambers

Abstract

In this thesis, the production of cellulose macroscale fibers from cellulose nanofibrils using flow focusing in microfluidic mixture chambers is examined and tested. This process accomplishes the difficult task of aligning cellulose nanofibrils and gelling them together to create macroscale cellulose fibers, and this study seeks to test the limit of macroscale cellulose fiber production using this method. Using a volumetric flow rate of 1.1 x 10-7 m3 /s, which is over 100 times greater than that from Nechyporchuk et al.'s 2018 experiments [11, cellulose nanofibrils were pumped through a microfluidic mixture chamber. Deionized water and hydrochloric acid were pumped through two different cross-flow channels at 5.28 x 10-7 m3/s and 1.32 x 10-6 m3 /s , respectively, to focus the nanofibril suspension flow. The mixture chamber was examined using video data to observe if the focusing and alignment of the nanofibril suspension occurs at these higher volumetric flow rates. Tests found that the flow can be narrowed to roughly 6% of its nominal width, and birefringence examinations indicate that the cellulose nanofibrils were being aligned due to the flow focusing. Furthermore, the use of an even higher volumetric flow rate is feasible for this process.