Functionalized Cellulose Nanofibrils Obtained from Cellulose Oxypropylated

The present study aimed to functionalize cellulose nanofibrils (CNFs) through the oxypropylation reaction and compare the number of cycles required to obtain the functionalized material in comparison to pristine cellulose pulp. Thereunto, the cellulose was submitted to an initial activation step with a sodium hydroxide solution, and reacted with propylene oxide in different values of molar ratio [OH_cellulose]/[PO], in autoclave, maintaining the constant temperature at approximately 135 °C. After obtaining the functionalized cellulose, the nanocellulose is obtained by passing its suspension (2% in distilled water) through a microfibrillator mill. Functionalized nanocellulose, as well as the cellulose pulp used throughout the process, were characterized by Fourier Transform Infrared Spectroscopy (FTIR), aiming to analyze whether the oxypropylation reaction was effective, evidenced by the appearance of new characteristic bands of the graft of the polyol chains. The samples were also characterized for their mass gain, Atomic Force Microscopy (AFM), X-Ray Diffraction (DRX) and Thermogravimetry (TG). The functionalized CNFs in comparison to non-functionalized CNF were obtained in fewer passes in the grinder, indicating that the functionalization of CNFs is attractive in terms of costs, since this fibrillation process impacts on a large energy demand in each pass through the grinder. Graphical Abstract: [Figure not available: see fulltext.].