Morphological and rheological properties of cellulose nanofibrils prepared by post-fibrillation endoglucanase treatment

Post-fibrillation endoglucanase treatment was employed to reduce the entanglement of cellulose nanofibrils (CNFs) produced with low extent of mechanical milling. The results showed that post-fibrillation endoglucanase treatment can effectively reduce the fibril degree of polymerization (DP) values and therefore entanglement. Cellulose DP was reduced from 520 for CNFs prepared by milling using a SuperMassColloider with 1 pass to 225 after endoglucanase treatment at a low dosage of 1 mg protein/g fibril for 24 h. Endoglucanase treatment can also effectively reduce the fibril mean diameter from 66 nm to 25 nm. Applying post-fibrillation endoglucanase treatment produced more uniform CNFs than the feed CNFs from pure mechanical treatment. All CNFs sus-pensions prepared by post-fibrillation endoglucanase treatment were non-Newtonian (except at very low con-centrations below 0.5 wt%) with shear thinning behavior. Post-fibrillation endoglucanase treatment reduced the viscosity of CNF suspensions due to decreasing fibril DP values and the extent of entanglement.