Preparation and characterization of nanocomposite films based on different ratios of cellulose nanocrystal and cellulose nanofiber

Cellulose nanomaterials (CNs) are of increasing interest due to their appealing inherent properties and show great promise in various applications such as reinforcing agent and barrier membrane. In this work, nanocomposite films composed with cellulose nanofiber (CNF) and cellulose nanocrystal (CNC) were prepared via vacuum filtration method. The effects of CNF/CNC ratios on the rheological behavior of nanocomposite suspension as well as the transparency, barrier performance, mechanical properties and thermal stability of nanocomposite films were investigated, and the microstructure of nanocomposite films was characterized. The results indicated that equal proportion of CNF and CNC appeared to be the optimal state for nanocomposite film preparation, at which the nanocomposite films exhibited compact network structures, desired thermal stability, a tensile strength of 60.5 MPa, water vapor transmittance of 923.9 g/m 2 /24 h (38 °C, 100% RH) and transparency of up to 92.7%. This work provides an effective and scalable approach for the preparation of nanocellulose based films with high performance, which may hold great promise in the biodegradable materials for advanced packaging applications. • Biodegradable CNF/CNC nanocomposite films were designed and prepared. • Optimal process for imparting desired properties to CNF/CNC films was identified. • Equal proportion of CNF/CNC was confirmed to be optimum state for film preparation. • CNF/CNC composite films exhibited desired transparency and mechanical properties. • Increased CNF amount resulted in increased viscosity of nanocomposite suspensions.