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arXiv · 1609.04639

Influence of humidity on the tribo-electric charging and segregation in shaken granular media

André Schella·Stephan Herminghaus·Matthias Schröter
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Abstract

We study the effect of humidity on the charge accumulation of polymer granulates shaken vertically in a stainless steel container. The setup allows to control the humidity level from 5 % to 100 %RH while performing automated charge measurements in a Faraday cup directly connected to the shaking container. We find that samples of approximately 2000 polymer spheres become highly charged at low humidity levels (<30 %RH), but acquire almost no charge for humidity levels above 80 %RH. The transition between these two regimes does depend on the material, as does the sign of the charge. For the latter we find a correlation with the contact angle of the polymer with only very hydrophilic particles attaining positive charges. We show that this humidity dependence of tribo-charging can be used to control segregation in shaken binary mixtures.

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André Schella, Stephan Herminghaus, Matthias Schröter. 2016-09-09. Influence of humidity on the tribo-electric charging and segregation in shaken granular media. https://arxiv.org/abs/1609.04639

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