Mechanical properties and failure mechanism of wood cell wall layers

In this paper, the deformation and failure behavior of a model nanocomposite that mimics the wood cell wall layer is studied using molecular dynamics simulation. The effect of microfibril angle (MFA) on the mechanical properties of the cellulose microfibril-reinforced nanocomposite is investigated. The measured elastic modulus in the simulations is found to be comparable with the estimation based on experimental measurements. Further more, the simulation results show that it is the local buckling of cellulose microfibril that causes the initiation of failure of the fiber-reinforced nanocomposites, i.e., the wood cell wall layers. Since kink band formation is the compressive failure mode of wood cell walls as well as the macroscopic wood, this suggests that the compressive failure of the micron-scale wood cell wall as well as the macroscopic wood may originate at the nanoscale as a consequence of the bulking of microfibrils. The effect of water on the mechanical properties of wood cell wall is also studied.