(666b) Environmental and Hydrophilic Effects on the Triboelectric Charging of Granular Insulator Materials

Triboelectric charging is a natural phenomenon that often plagues many manufacturing processes. Electrical charge is transferred when two material surfaces contact and separate from each other. This phenomenon attributes to a wide range of occurrences, such as volcanic lightning and grain silo explosions. Currently, the mechanisms and variables that affect triboelectrification are unclear and poorly understood. Three mechanisms: electron, ion, and mass transfer, are believed to be responsible for the charge transfer, and are considered explanations for the occurrence of triboelectric charging. Variables, such as relative humidity and hydrophilicity, contribute to the sign and magnitude of charging that transpires. To investigate these variables and the mechanisms responsible for triboelectric charging of insulators, a particle (300-800 μm) is gravitationally driven through a spiraled insulator tube (ID 1.5 mm). The tube is held in a controlled chamber that holds a near-zero humidity environment. Two types of particles (soda lime glass, polystyrene) and tubing (Nylon, Teflon) were studied due to their inherently different hydrophilicities and partial charges. The rate of charge accumulation was recorded, as the particle traversed through the copper Faraday tube. The charged particle was collected in a Faraday cup, and the total accumulated charge on the particle was calculated. This study aims to isolate triboelectric charging at near zero relative humidity, as well as to gain a better understanding of the mechanisms responsible for triboelectric charging of insulators.