Monitoring fibrillation in the mechanical production of lignocellulosic micro/nanofibers from bleached spruce thermomechanical pulp.

The present work aims at assessing the main characteristics of lignocellulosic micro/nanofibers (LCMNF) from bleached thermomechanical pulp (BTMP) from spruce while glimpsing the suitability of cationic demand (CD) as effective monitoring parameter of the fibrillation process. For this, BTMP was mechanically refined at different times in a Valley beater, aiming at determining the required refining time and fiber length to be later fibrillated in a high-pressure homogenizer. It was found that 150 min treatment is required to avoid clogging in the pressure chambers of the homogenizer. The mechanically treated BTMP was gradually passed through a high-pressure homogenizer, leading to four LCMNF with different fibrillation degree. The main characteristics of the LCMNF were determined, as well as the effect that high-pressure homogenization may generate onto the LCMNF structure. It was observed that CD is a robust parameter to monitor the fibrillation process, as it is a good indicator of the LCMNF characteristics. In addition, it was found that WRV may not be a good indicator of the extent of fibrillation for LCMNF, as the lignin content varies with the homogenization intensity. Finally, the limitations of CD as monitoring parameter and perspectives on this regard are provided to the reader.