Cellulose Nanocrystals: Tensile Strength and Failure Mechanisms Revealed Using Reactive Molecular Dynamics

Cellulose nanocrystals (CNCs) offer excellent mechanical properties. However, measuring the strength by performing reliable experiments at the nanoscale is challenging. In this paper, we model Iβ crystalline cellulose using reactive molecular dynamics simulations. Taking the fibril twist into account, structural changes and hydrogen-bonding characteristics of CNCs during the tensile test are inspected and the failure mechanism of CNCs is analyzed down to the scale of individual bonds. The C4-O4 glycosidic bond is found to be responsible for the failure of CNCs. Finally, the effect of strain rate on ultimate properties is analyzed and a nonlinear model is used to predict the ultimate strength of 9.2 GPa and ultimate strain of 8.5% at a 1 s^-1 strain rate. This study sheds light on the applications of cellulose in nanocomposites and further modeling of cellulose nanofibres.