Coarse-grained modeling of nanocellulose network towards understanding the mechanical performance

Owing to the impressive mechanical properties and renewability, nanocellulose has been increasingly used for the development of lightweight materials in various applications. Here, we present a coarse-grained (CG) modeling study for investigations of mechanical performance of cellulose-based bulk material consisting of disordered cellulose nanocrystals (CNCs), forming a porous network microstructure. The simulation results reveal that increasing density and cohesive interaction between CNCs leads to an increase in shear modulus and yield stress of bulk system, which strongly depends on the cohesive energy density of the system. Notably, by evaluating the local "molecular" stiffness, the bulk CNCs system tends to become more dynamically heterogeneous with increasing density and cohesive interaction, which is similar to glass-forming liquids such as polymers. Such influence on shear modulus and dynamical heterogeneity of bulk CNCs is found to be more pronounced with variation of density, which is likely due to the high rigidity of CNC and high porosity of network microstructure. Our study provides fundamental insights into the mechanical behavior of bulk nanocellulose under the influences of key microstructural and interfacial features, which is crucial to develop an extension of structure-property relationships as established for engineering materials. (C) 2020 Elsevier Ltd. All rights reserved.