Influence of nanoparticles mechanical properties on macrocracks formation

TL;DR

This study investigates how the mechanical properties of nanoparticles, specifically the ratio of hard to soft nanolatex spheres, influence crack formation in drying films, revealing a critical composition threshold and stress release mechanisms.

Contribution

It provides experimental insights into how nanoparticle deformability affects crack formation and elastic properties in drying nanolatex films, introducing a tunable approach.

Findings

Cracks form only when the hard sphere proportion exceeds ~0.45.

Soft particles deform to release internal stresses during drying.

Crack spacing varies with layer thickness and composition.

Abstract

We present an experimental investigation of drying suspensions of both hard and soft nanolatex spheres. The crack formation is examined as a function of the proportion of hard and soft deformable particles, leading to tunable elastic properties of the drying film. In our experiments corresponding to a given layer thickness, no crack formation could be observed below an onset value of the proportion in hard spheres around 0.45. During the drying process, the mass of films with various compositions in hard and soft spheres is measured as a function of time. The results suggest that the soft particles undergo deformation that releases the internal stresses. The spacing between cracks is measured as a function of the layer thickness for various compositions in hard and soft spheres.