Drying and cracking mechanisms in a starch slurry

Abstract

Starch-water slurries are commonly used to study fracture dynamics. Drying starch-cakes benefit from being simple, economical, and reproducible systems, and have been used to model desiccation fracture in soils, thin film fracture in paint, and columnar joints in lava. In this paper, the physical properties of starch-water mixtures are studied, and used to interpret and develop a multiphase transport model of drying. Starch-cakes are observed to have a nonlinear elastic modulus, and a desiccation strain that is comparable to that generated by their maximum achievable capillary pressure. It is shown that a large material porosity is divided between pore spaces between starch grains, and pores within starch grains. This division of pore space leads to two distinct drying regimes, controlled by liquid and vapor transport of water, respectively. The relatively unique ability for drying starch to generate columnar fracture patterns is shown to be linked to the unusually strong separation of these two transport mechanisms.

9 pages, 8 figures [revised in response to reviewer comments]

References in corpus (2)

• An Experimental Investigation of the Scaling of Columnar Joints
• Numerical study of drying process and columnar fracture process in granules-water mixtures

Cited by in corpus (8)

• Evolving fracture patterns: columnar joints, mud cracks, and polygonal terrain
• A cohesive granular material with tunable elasticity
• Universal Scaling of Polygonal Desiccation Crack Patterns
• Morphometric analysis of polygonal cracking patterns in desiccated starch slurries
• Cracking Condition of Cohesionless Porous Materials in Drying Processes
• Flow velocity-dependent transition of anisotropic crack patterns in CaCO${}_3$ pastes
• Universal fluctuation of polygonal crack geometry in solidified lava
• Experimental investigations on the nonequilibrium dynamics of pattern formation in fluid and granular systems