Schella, AndréHerminghaus, StephanSchröter, Matthias2020-02-182020-02-182017-011744-683X1744-6848https://hdl.handle.net/10161/20170We study the effect of humidity on the charge accumulation of polymer granulates shaken vertically in a stainless steel container. This setup allows us 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.Science & TechnologyPhysical SciencesTechnologyChemistry, PhysicalMaterials Science, MultidisciplinaryPhysics, MultidisciplinaryPolymer ScienceChemistryMaterials SciencePhysicsCONTACT ELECTRIFICATIONTRIBOELECTRIC SERIESELECTROSTATIC DISCHARGESURFACE MODIFICATIONFORCE MICROSCOPYSOLID-SURFACESWATERPOLYMERSSEPARATIONINTERFACESJournal article2020-02-18