Mechanical properties of cellulose nanofibrils determined through atomistic molecular dynamics simulations

We have carried out atomistic molecular dynamics simulations to study the mechanical properties of cellulose nanofibrils in water and ethanol. The studied elementary fibrils consisted of regions having 34 or 36 cellulose chains whose cross-sectional diameter across the fibril was roughly 3.4 nm. The models used in simulations included both crystalline and non-crystalline regions, where the latter were designed to describe the essentials parts of amorphous cellulose nanofibrils. We examined different numbers of connecting chains between the crystallites, and found out that the elastic constants, inelastic deformations, and strength of the fibril depend on this number. For example, the elastic modulus for the whole fibril can be estimated to increase by 4 GPa for each additional connecting chain.