Effect of enzyme beating on grinding method for microfibrillated cellulose preparation as a paper strength enhancer

Hardwood bleached Kraft pulp was treated with an endoglucanase prior to Valley beating. The Valley-beaten pulp slurry was further ground with a particle grinder in order to evaluate the effect of enzyme beating on preparation of microfibrillated cellulose (MFC). The time required to make 100 mL Canadian Standard Freeness pulp slurry was greatly reduced by enzyme pre-treatment. The viscosity of the enzyme-beaten MFC slightly increased with grinder pass number; however, the rate of change in viscosity was much lower than that of non-enzyme-beaten MFC. The crystallinity of MFC decreased with grinder pass number for both cases. The drainage of the pulp slurry containing enzyme-beaten MFC was higher than that of the pulp slurry containing non-enzyme-beaten MFC. Further, the enzyme-beaten MFC subjected to the 10 passes grinding had the same tensile index as the MFC subjected to the 15 passes grinding. Thus, the mechanical energy for MFC manufacturing can be greatly reduced with enzyme beating.