Eliminating cracking during drying

TL;DR

This paper presents a method to eliminate cracking during drying of colloidal suspensions by adding emulsion droplets, which reduces stresses and controls drying rate, with minimal impact on final product composition.

Contribution

Introducing emulsion droplets into colloidal suspensions as a novel technique to prevent cracking and regulate drying speed during evaporation.

Findings

Cracking is completely eliminated above a critical droplet concentration.

Adding droplets allows control over drying rate.

The method minimally alters the final product composition.

Abstract

When colloidal suspensions dry, stresses build up and cracks often occur - a phenomenon undesirable for important industries such as paint and ceramics. We demonstrate an effective method which can completely eliminate cracking during drying: by adding emulsion droplets into colloidal suspensions, we can systematically decrease the amount of cracking, and eliminate it completely above a critical droplet concentration. Since the emulsion droplets eventually also evaporate, our technique achieves an effective function while making little changes to the component of final product, and may therefore serve as a promising approach for cracking elimination. Furthermore, adding droplets also varies the speed of air invasion and provides a powerful method to adjust drying rate. With the effective control over cracking and drying rate, our study may find important applications in many drying and cracking related industrial processes.