Effect of Interaction on the Formation of Memories in Paste

Abstract

A densely packed colloidal suspension with plasticity, called paste, is known to remember directions of vibration and flow. These memories in paste can be visualized by the morphology of desiccation crack patterns. Here, we find that paste made of charged colloidal particles cannot remember flow direction. If we add sodium chloride into such paste to screen the Coulombic repulsive interaction between particles, the paste comes to remember flow direction. That is, one drop of salt water changes memory effect in the paste and thereby we can tune the morphology of desiccation crack patterns more precisely.

Crack patterns over uneven substrates

“…At this concentration the slurries behaved as fluids, rather than pastes. These conditions avoid the memory effect [29,30], whereby the flow or vibration of a yield-stress paste can affect the way it cracks (see Fig. 1(f)).…”

Mechanism of memory effect of paste which dominates desiccation crack patterns

“…in the x-direction, and α = 0 corresponds to the initial state before the horizontal vibration is applied. Then, the relaxation of α can be roughly given by [13,14].…”

“…In this article, we first review the case that, even without any drying gradient, we can control and get regular anisotropic desiccation crack patterns by using memory effect of paste [11][12][13][14][15]. Since a paste behaves as a plastic fluid, it remembers the direction of its motion, such as vibration or flow, and the memory of such motion determines the preferential direction for cracks to propagate.…”

Electric-field-induced crack patterns: Experiments and simulation

“…The patterns created by the network of desiccation cracks formed under different conditions has been a subject of research for a long time [1][2][3] and is still an active field [4][5][6].…”