A fast method to prepare mechanically strong and water resistant lignocellulosic nanopapers

Abstract

This study covers a green method to prepare hybrid lignocellulosic nanopapers by combining wood nanofibres (WNFs) and cellulose nanofibres (CNFs). The WNFs and CNFs behave synergistically to compensate for the drawbacks of each other resulting in enhanced hybrid nanopapers. The draining time of hybrid nanopapers was improved by up to 75% over CNF nanopaper, and the mechanical properties (modulus, strength and elongation) were respectively improved up to 35%, 90% and 180% over WNF nanopaper. Additionally, the water resistance of hybrid nanopapers was considerably improved with a water contact angle of 95°; the neat CNF nanopaper had a contact angle of 52°. The morphology of nanopapers, studied by electron microscopy, indicated that lignin acts as a matrix, which binds the nanofibres together and makes them impervious to external environmental factors, such as high humidity. The reported hybrid nanopapers are 100% biobased, prepared by a simple and environmentally friendly processing route. Reported hybrid nanopapers can be used in novel applications such as gas barrier membranes and printable electronics.

Hydrophobic modification of nanocellulose and all-cellulose composite films using deep eutectic solvent as a reaction medium

“…6d). In addition, the stress-strain curves did not show a clear yield points at all, indicating that the films transferred straight into strain-hardening region and deformed (Benitez et al 2013;Sethi et al 2019). Compared with the humid conditions, the wet CNF and ACC films behaved differently, i.e., ACC films exhibited clearly higher tensile strengths (31-40 MPa) than that of CNF films (18)(19)(20)(21)(22)(23)(24)(25)(26)(27).…”

“…When the composite is fully wetted, the matrix is plasticized, but the matrix promotes wet strength, and the slippage of the composite is not as severe as of the nanofibrils (Benitez et al 2013;Sethi et al 2019). For the other samples, tensile strengths and moduli are lower at 50% RH than at 0% RH, because water breaks the interfibrillar hydrogen bonds, causing interfibrillar slippage, thus allowing the film stretch under stress (Benitez and Walther, 2017).…”

Transparent lignin-containing wood nanofiber films with UV-blocking, oxygen barrier, and anti-microbial properties

“…The effects of lignin have previously been shown in contact angle measurement 19 and water absorption 18 and in improved strength properties at elevated humidity and in a wetted state. 69 Contradictory results have also been reported, highlighting the effect of its morphology, and other possible factors, on the hydrophobicity of WNF lms. In addition, the presence of lignin has also been shown to improve the oxygen barrier properties of WNFs at an RH of 50%, whereas the opposite effect was observed at higher humidity.…”

Fabrication of lignocellulosic biomass paper containing nanofibrillated biomass

“…Pouring fibrillated biomass slurry directly over a stainless-steel mesh made the filtration complete in less than 1 min in comparison to using regenerated cellulose, polyvinylidene difluoride, or nylon membranes, which can take a longer time to filter. In either case, the fast filtration of nanofibrillated biomass is a big advantage over nanofibrillated cellulose that can take over an hour to filter (Sethi et al 2019). The other advantage of directly filtering over the No.…”

“…Whole biomass nanofibers that contain high lignin content have only recently been produced for making nanopapers. Ultra-friction grinding of mechanical pulp (spruce groundwood) has been carried out to obtain wood nanofibers (WNF) to make lignocellulosic nanopapers (Visanko et al 2017;Sethi et al 2019). However, the constitution of papers from fibers recovered from ultra-friction grinding of knife-milled biomass without prior mechanical pulping has not been performed.…”