This study examined the physicochemical and mechanical properties of edible composite films made of cellulose nanofiber (CNF) and shellac (Sh). All films were conditioned at 25℃ and 53% relative humidity (RH) for at least 48 h before analyses. Increasing the Sh ratio from 0% to 100% resulted in an increase in film thickness from 57.8 μm to 71.1 μm, while opacity decreased significantly from 22.3 mm⁻¹ to 3.7 mm⁻¹. With the increase in the Sh ratio, the moisture content, water solubility, and swelling of the film increased from 9.7% to 35.1%, 4.9% to 100%, and 3.0% to 10.5%, respectively. The CNF film (0% Sh) exhibited a lower water contact angle than the films with 80% and 100% Sh, but it was more water-resistant. As the Sh ratio increased, the tensile strength, yield stress, Young’s modulus, and work of break of the films decreased significantly from 17.9 MPa to 0.3 MPa, 1.00 MPa to 0.38 MPa, 220.7 MPa to 0.9 MPa, and 0.67 MJ/m3 to 0.13 MJ/m3, respectively. Conversely, the elongation at break increased dramatically from 10% to 253%. This study demonstrated that the thickness, opacity, moisture-related properties, and mechanical properties of CNF-Sh composite films could be tailored by varying the biopolymer ratio.

The significance of this study lies in addressing critical issues prevalent in the worldwide construction sector, particularly concerning the durability and sustainability of cement-based materials. Plain cement composites commonly suffer from deficiencies in tensile strength and strain capacity, resulting in the formation of nano-cracks under relatively low tensile loads. These nano- cracks pose a significant challenge to the longevity and resilience of cement matrices, contributing to structural degradation and reduced service life of infrastructure. To mitigate these challenges, the integration of cellulose nanofibers (CNF) as reinforcements in cement composites presents a promising solution. CNF, renowned for their exceptional material properties including high stiffness, tensile strength, and corrosion resistance, offer the potential to significantly enhance the mechanical performance and durability of cement-based materials. Through systematic experimentation, this study investigates the effects of CNF reinforcement on the mechanical properties of cement composites. By leveraging ultrasonically dispersion techniques, CNF extracted from bamboo, broad leaf, and kenaf are uniformly dispersed within the cement matrix at varying concentrations. Compressive and flexural tests are subsequently conducted to evaluate the impact of CNF on the strength characteristics of the cement composites. By elucidating the efficacy of CNF reinforcement through rigorous experimentation, this study aims to provide valuable insights into the development of construction materials with improved durability and sustainability. Ultimately, this research contributes to addressing critical challenges in the construction industry, offering potential solutions to enhance the performance and longevity of cement-based infrastructure.