Coupled spreading-fraction effects of polymer nano-binder on the network connectivity and tensile modulus of porous mineral coatings

A numerical model was developed that combines complex porous coating microstructures with continuum mechanics simulations. Platy (hexagonal plates) and blocky (frusta) particles were packed computationally. Polymer nano-bridges were then placed between the packed particles to establish network continuity. Slices from the 3-dimensional packings were extracted and a finite element method implemented to determine the mechanical properties. As a function of shape, high aspect ratio plates might be expected to resist load more effectively than 1:1 aspect ratio frusta. However, when the polymer fractions are high and there is low binder spread across the particle surfaces, the frustum packings exhibit higher tensile modulus values than the platy packings. These packed frusta have more stable solid state networks than higher aspect ratio platy packings and consequently resist load more effectively.