Memories of paste
- Weitz, D., Nature 410, 32-33 (2001).
In his article, Weitz primarily describes the following paper:
- Cloitre, M., Borrega, R. & Leibler, L. Phys. Rev. Lett. 85, 4819-4822 (2000).
Key Words: Paste, Glass, Microgel, Stress, Relaxation, Ageing
Weitz's article draws attention to the findings of Cloitre, Borrega, and Leibler and goes on to list related questions for future exploration.
Cloitre, Borrega, and Leibler studied the rheology of a paste consisting of pieces of microgel suspended in a fluid.
The related questions Weitz lists are:
- 1) What causes the ageing affect?
- 2) How much impact does the surprising rheology have?
- 3) Is the ageing affect specific to the particular microgel paste, or does it apply to other pastes or even other kinds of soft matter?
Soft Matter Details
Types of Soft Matter
As the title suggests, Memories of Paste focuses primarily on a class of soft materials called pastes. However, the author remarks on a similarity between pastes, gels, and glasses. "...the way a paste recovers from an applied stress is remarkably like the behaviour of glasses and gels." (p.32)
- What is the differences between pastes, colloids, glasses, and gels?
"Pastes typically consist of a suspension of small particles in a background fluid. These particles are crowded, or jammed together like grains of sand on a beach, forming a disordered, glassy, or amorphous structure." (p.32)
A colloid is a suspension of solid particles in a liquid, so it seems that a paste is a type of colloid where the volume fraction of solid particles is quite high.
The property of the specific microgel paste highlighted in this article is a stress-relaxation aging relationship.
Cloitre et al. made bulk rheological measurements to study a paste's response to stress.
author: Becca Perry