Microstructure and Size Effects on the Mechanics of Two Dimensional, High Aspect Ratio Nanoparticle Assemblies

Abstract

Uniaxially arranged nanocomposite structures are common across biological materials. Through efficient structural ordering and hierarchies, these materials exhibit stiffnesses and strengths comparable to the better of their constituents. While much is known regarding the mechanical properties of materials with explicit stiff and compliant phases, substantially less is understood about neat (matrix-free) materials composed from high aspect ratio particles. A promising example of nanoparticle assemblies are cellulose nanocrystal (CNC) thin films, which display desirable elastic and failure properties. Despite the exceptional properties of CNC films, accurately linking their nanoscopic properties to macroscale performance remains a challenge. Therefore, this work assesses the effects of fiber geometry and in-plane topology on the elastic and failure behaviors of neat CNC thin films using an atomistically informed coarse-grained molecular dynamics model. Short fiber films show a greater dependence on their specific in-plane ordering compared to longer fiber films. Furthermore, aligned, brick, and mortar type CNC films exhibit a remarkable resiliency to random structural perturbations, particularly for films built from long fibers. Finally, simulation size is shown to affect the apparent failure properties of CNC films, with no meaningful impact on elastic property predictions. The relationships between structure and fiber length, as well as the sensitivities to structural randomness and simulation size, elucidated herein provide a comprehensive overview of the expected mechanics of high aspect ratio nanoparticle assemblies.

Lignin–Cellulose Nanocrystals from Hemp Hurd as Light-Coloured Ultraviolet (UV) Functional Filler for Enhanced Performance of Polyvinyl Alcohol Nanocomposite Films

“…A significant difference was found between L-CNCs3 and L-CNCs7. The increase in Young's modulus in the L-CNCs/PVA films could be the result of two phenomena; (1) the formation of rod-like cellulose nanocrystals as observed by the AFM result and (2) the aspect ratio of hemp particle and L-CNCs [75].…”

A new constructive algorithm for random polydisperse dense disk pack generation

“…Depending on the research area, granular materials vary from small-scale molecules and dust to large-scale celestial bodies. [1][2][3][4][5] Among numerical methods for studying granular materials, the discrete element method (DEM) formulated by Cundall and Strack 6 is the most popular. This method assumes that a granular medium within a domain can be represented by a large set of individual particles.…”

“…The research scope ranges from mining and 3D printing to pharmaceutical processing. Depending on the research area, granular materials vary from small‐scale molecules and dust to large‐scale celestial bodies 1‐5 …”

General Fishnet Statistics of Strength: Nacreous, Biomimetic, Concrete, Octet-Truss, and Other Architected or Quasibrittle Materials

“…Recently, it has been shown that a thin film of cellulose nanocrystal has a statistical size effect similar to fishnet's [22], implying that the fishnet model may apply to this type of material. Thanks to the general formulation of the fishnet probabilistic model, we can apply it at the low probability tail to quasibrittle particulate materials such as concrete, to fiber composites, and to architected nanomaterials such as the octet-truss nanolattice.…”