Benchmarking the Production of Cellulose Nanofibres: Biomass Feedstock, Mechanical Processing, and Nanopaper Performance

Lignocellulosic biomass plays a vital role in the global shift away from the utilisation of non-renewable petrochemical resources. An emerging class of biomass-derived material is nanocellulose, which are typically generated from the deconstruction of cellulose bundles within the cell wall of terrestrial and aquatic plants, either in the form of cellulose nanocrystals (CNCs) or cellulose nanofibres (CNFs). However, the utilisation of biomass has an inherent challenge associated with product variability, both in terms of the starting feedstock properties, the wide range of processing routes available to generate nanocellulose, and the fabrication of nanocellulose into a diverse range of different product formats. As a result, it is difficult to accurately characterise and benchmark the wide variety of nanocellulose materials described within the literature. To address this challenge, this study presents a threefold benchmarking assessment of CNF-based material, including: (1) CNFs generated from different biomass sources (sorghum, banana, sugarcane, spinifex, and softwood); (2) CNFs generated through different mechanical processing methods (Silverson mixing, twin-screw extrusion, bead milling, and high pressure homogenisation); and (3) Energy-standardised nanopaper mechanical performance presented within applicable literature studies. The biomass benchmarking study highlighted sorghum and banana stem as comparatively sustainable biomass feedstock, while the mechanical process benchmarking study highlighted twin-screw extrusion as a promising fibrillation method with relatively low energy consumption. Lastly, the nanopaper benchmarking study aided in the visualisation of the nanopaper research landscape. Overall, sample benchmarking in this manner provides greater insight into the mechanisms driving nanocellulose material performance and processing sustainability.