A comparative analysis of the characteristics of cellulose nanof ibril films fabricated by batch-wise mode

In this paper, we compare the physical and mechanical characteristics of cellulose nano-fibril (CNF) films fabricated using the solvent casting and vacuum filtration methods through a statistical analysis to facilitate the process of CNF film fabrication and CNF quality assurance. For a given CNF film diameter targeting 30 grammage (g/m²), the typical solvent-casting method requires longer fabrication time (up to four days) owing to the slow drying process, whereas vacuum filtration combined with elevated drying temperatures (from ambient to 80°C) significantly reduced the fabrication time up to 5 h. There were some differences in the apparent densities and tensile indexes of the CNF films fabricated via the solvent casting and vacuum filtration methods, depending on how quickly the wet-web and drying temperatures consolidated under applied pressure. The higher drying temperatures used in the vacuum-filtration method tended to increase the tensile index of the films. However, according to the results of the Tukey honestly significant difference (HSD) test, the tensile indexes and elongations of the films fabricated using the vacuum filtration method were not statistically different from those of the films fabricated using the solvent casting method, suggesting that the method of preparation of CNF films by combining the vacuum filtration approach with elevated drying temperatures could be used as a tool to assess the characteristics of CNF materials.