Regensburg 2016 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 5: Colloids and Complex Fluids II (joint session CPP/BP/DY)

DY 5.8: Invited Talk

Monday, March 7, 2016, 11:45–12:15, H51

Percolation in colloidal model systems — •Tanja Schilling¹, Hugues Meyer¹, Mohit Dixit¹, Mark Miller², and Paul van der Schoot³ — ¹Physics and Materials Science Research Unit, University of Luxembourg, Luxembourg — ²Department of Chemistry, Durham University, United Kingdom — ³Theory of Polymers and Soft Matter, Technische Universiteit Eindhoven, 5600 MB Eindhoven, The Netherlands

Connectivity percolation is the transition in which isolated clusters of solid particles in a fluid become connected in some sense to form a system-spanning network. This network has a significant effect on the transport properties of the material on a macroscopic scale. If, for example, an electrically insulating polymer is mixed with conductive fibres such as carbon nanotubes, the conductivity of the composite increases by ten or more orders of magnitude near the percolation transition of the filler material.

We discuss percolation in suspensions of fibres and of platelets. Our study covers the entire range of aspect ratios from spheres to extremely slender rods and infinitely thin disks. The percolation threshold for rod-like particles of aspect ratios below 1000 deviates significantly from the inverse aspect ratio scaling prediction, thought to be valid in the limit of infinitely slender rods and often used as a rule of thumb for fibres in composite materials. We also show the effects of polydispersity on the percolation transition. The main result is that the percolation threshold shows universal behaviour, i.e. it depends only on certain cumulants of the size distribution.