Mechanical processing control in manufacturing nanofibrillated cellulose by interpreting its rheological properties

Nanofibrillated cellulose (NFC) has generated significant interest due to growing concerns about low carbon emission, environmental issues, and the guaranteed outstanding performance of applied products. Because of this trend, the importance of NFC production from an industrial angle has also been emphasized. In this study, ground pulps (at -300 μm clearance, 40 passes) were homogenized by using a pilot-scale microfluidizer (at 1,500 bar, up to 5 passes) to produce the NFC, and its characteristics were investigated. Scanning electron microscope (SEM) images showed that the size and distribution of the NFC particles gradually decreased by up to three passes on account of the microfluidizer treatment and remained constant after that mechanical pass number. The viscoelastic properties (dynamic moduli) and viscosity of the NFC suspension steadily increased with three passes of the treatment, and the same trends as in the SEM images were observed after these passes. These results demonstrated that the NFC fluid behavior inside the equipment depends on the morphological properties of the manufactured NFC particles. Additionally, a good agreement between the morphological and rheological results implied that rheological analysis can be a reasonable approach to predicting the quality (size and distribution) of manufactured NFC particles.