High-consistency milling of oxidized cellulose for preparing microfibrillated cellulose films

Microfibrillated celluloses (MFCs) with a high elongation potential were fabricated from periodate–chlorite oxidized cellulosic fibers (anionic charge density of 1.75 mmol/g) using high consistency milling conducted at a solids content of 7.5–15 % with a PFI mill. MFC gels were obtained after 5000 milling revolutions and after 30,000 revolutions MFCs with lateral dimension ranging from 10 to 100 nm and length up to micron-scale were obtained from all samples according to scanning electron microscopy imaging. The crystallinity in terms of crystalline indexes of MFCs was similar to untreated pulp (~65 %). Free-standing films produced from the MFC samples (milled for 30,000 revolutions) had the ultimate tensile strength and Young’s modulus of 61–115 MPa and 8–11 GPa, respectively. The films also showed very high stretchability potential in terms of strain at break values of 6.8–15.9 %. Thus, the results suggest that high consistency milling with high production capacity and decreased energy consumption can potentially be used to fabricate MFC with high mechanical performance for bulk applications.