Cellulose Nanofibrils as Reinforcement in the Process Manufacture of Paper Handsheets

The objective of this study was to better understand the effect of micro/nanofibrils added as reinforcement on paper handsheets, their physical-mechanical performance and barrier properties, and to determine the ideal cellulose nanofibrils (CNF) proportion to increase such paper properties. Mechanically produced CNF were added at increasing amounts (0%, 2%, 5%, 8% and 10%) to commercial Eucalyptus pulp to produce paper handsheet samples. Morphology, crystallinity, physical-mechanical and air barrier properties of the paper handsheets were evaluated. The results suggested that adding CNF has decreased the presence of empty spaces inside and on the surface of the paper handsheets by up to 61% due to the interaction between fibers and nanofibrils. The paper handsheets became denser, more compact and resistant to passage of air, as well as with greater mechanical performance with higher CNF content (10%). The bursting index is approximately 5 times higher on paper with addition of 10% of CNF compared to control paper handsheets. There were significant gains in the studied properties without any change in CNF/fibers surface charge or the use of any cationic polymer to assist the retention of nanofibrils and fibers. This study highlights the potential of CNF as additives in papermaking process, increasing its properties.