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

摘要

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 (similar to 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.