Dynamics of drying nanoparticle suspensions
Abstract
When a suspension in a capillary tube is allowed to evaporate at one end, fluid flow results in an accumulation of close-packed particles at the end where evaporation occurs. Cracks propagate in the region where the particles are close-packed, and the length of the cracks is limited by the extent of this region. Therefore as a precursor to understanding more about the cracking process, we consider the growth of the region of close-packed particles. Our measurements of the dynamics show qualitatively different trends from those in other geometries, such as the sessile drops studied by Deegan et al. (1997). The difference arises because in the geometry we study, fluid is forced to pass through the region of close-packed particles. We present a theoretical model that balances the evaporative driving force with the resistance to flow in the region of close-packed particles, which captures the crossover between two different limiting cases of the dynamical behavior. Interestingly, the experimental data show that the fluid flux through the close-packed region goes to zero when the inter-particle pore size is comparable to the size of a solvent molecule.
- Publication:
-
APS Division of Fluid Dynamics Meeting Abstracts
- Pub Date:
- November 2003
- Bibcode:
- 2003APS..DFD.MK008A