Polarity change in the tribo-charge of particles with and without an initial charge

Simultaneous measurements of particle charge density and bubble properties in gas-solid fluidized beds by dual-tip electrostatic probes

“…This may be because of the combined effect of triboelectrification and transfer of charges or contamination of the probe tip surfaces. Similar phenomena were reported by He et al (2014a);John et al (1980) and Tanoue et al (2005). The sign of the cumulative charge signals does not necessarily represent the polarity of charge on particles.…”

Electrostatic charging during the flow of grains from a cylinder

“…While the distribution of charge, among particles based on particle size, collision angle, and humidity have been investigated previously [27][28][29]45], the present results indicate that even a simple granular flow can develop a complicated charge distribution. This suggests that many of the flow problems and segregation caused by electrostatic forces may be caused by a relatively small number of grains.…”

“…It could also be used to detect the presence of coatings. The coating of a material with another changes the charging behavior of the mixture whether or not the coating was deliberate [13,34,35], or accidental, as could be caused by a contaminate [29,55]. It is possible that a change in the surface properties of a material, such as a contaminate coating, could be detected as a change in the charging properties of the material.…”

“…For example, the charge developed by a material through triboelectrification is known to depend on extrinsic factors including humidity [22][23][24], surface chemistry [25], contamination [25,26], and particle size [27,28]. Even the determination of the charge of particles for a single material can be a challenge as particles often acquire nonuniform distributions of charges [27][28][29]. Tanoue et al [29] have shown that the polarity of the charge developed by a particle may depend on its impact angle with a target.…”

“…Even the determination of the charge of particles for a single material can be a challenge as particles often acquire nonuniform distributions of charges [27][28][29]. Tanoue et al [29] have shown that the polarity of the charge developed by a particle may depend on its impact angle with a target. Moreover, Lowell and Truscott [30] as well as Komatsu et al [31] have shown that even identical materials can charge one another depending on the nature of contact between them, and Lacks and Levandovsky [28] have proposed a mechanism that could explain the tribocharging observed between particles of the same material but differing sizes.…”