Optimizing cellulose fibrillation for the production of cellulose nanofibrils by a disk grinder

Abstract

Abstract The fibrillation of a bleached kraft eucalyptus pulp was investigated by means of a laboratory-scale disk grinder for the production of cellulose nanofibrils (CNF), while the parameters disk rotating speed, solid loading, and fibrillation duration were varied. The cumulative energy consumption was monitored during fibrillation. The degree of polymerization (DP) and water retention value (WRV) of the resultant cellulose fibrils were determined as measures of the degree of fibrillation, which was also visualized by scanning electron microscopy, field emission-scanning electron microscopy, and transmission electron microscopy imaging. A higher rotating speed than 1500 rpm did not improve the fibrillation judged by DP and WRV measurements. Solid loading has an insignificant effect on fibrillation in a wide range. The energy consumption (E) was determined as a function of the DP and WRV. The optimal grinding conditions were between 1200 and 1500 rpm at 2.0%–2.2% solid loading.