Effect of lignin content on the microstructural characteristics of lignocellulose nanofibrils

The microstructure and properties of lignocellulosic fibers usually change during the drying process due to the hornification of fibers. The water retention ability of fibers is an effective way to reflect the degree of fiber hornification. In this study, the effects of lignin content on the microstructural properties of dried-redispersed LCNFs (DLCNFs) were extensively explored. The results showed that the high content of lignin could maintain the microstructural integrity of DLCNFs. The water retention value and hornification degree of high lignin content DLCNFs (22.1%, w/w) were 289.8% and 6.9%, which were much lower than those of low lignin content (6.2%, w/w) DLCNFs. This was probably because that the crosslinking between lignin and carbohydrate effectively prevented the hydrogen bonding formation in the interior-fibers and exterior-fibers, and reduced the irreversible hornicficatoin of LCNFs. This study will be beneficial for the development of the LCNF drying mechanism. Graphic abstract