Enhanced Impact Resistance of Bouligand Films with Discontinuous Cellulose Nanocrystal Nanofibers

Significant knowledge gaps exist in the understanding of the dynamic mechanical behaviors of thin films consisting of discontinuous nanofibers with a Bouligand microstructure. In this study, we applied coarse-grained molecular dynamics simulations to investigate the impact resistance of Bouligand microstructural films with integrated defects, i.e., aligned but discontinuous cellulose nanocrystal nanofibers. Through explicit projectile impact simulations, we have investigated the impact resistance of Bouligand CNC films depending on different variables, such as defect types, fiber length (or defect density), and pitch angle. Typical ballistic impact indicators, e.g., ballistic limit velocity and penetration energy, were adopted to analyze the impact resistance. We find that defects within the discontinuous microstructure for certain fiber lengths and pitch angles can allow for better performance than continuous counterparts in impact resistance. This study fosters a deeper understanding of the dynamic mechanical behaviors of thin films with the Bouligand microstructure and potential methods to enhance the impact resistance of such films.