the triboelectric effect

=physics

When different materials are rubbed together, charge transfer happens between them. Why that happens is still poorly understood, so I was thinking about what might cause it, and had some related thoughts.

filter masks

Filter masks have become more important because of COVID-19, and electrostatic effects are important for the effectiveness of N95 masks. Typically, those have "electret fibers" which have particles (eg barium titanate) added, but that does increase costs, and production capacity of those fibers is currently insufficient.

It occurred to me that it might work to instead use multiple layers of different materials for filter masks to improve their filtration, by generating electrostatic charge when they rub against each other. And that does seem to be the case. The combination that came to mind for me was polypropylene + cotton + nylon.

mineral deposition

Dissolved minerals in water can't deposit directly on hydrophobic plastic. So, how do plastic pipes get mineral buildup in them?

I suspect that mineral deposition on the inside of polymer pipes starts with small particles electrostatically adhering to the polymer surface, and mineral deposition occurring on those particles. That means that mineral deposition would involve particles charging the pipe surface by colliding with it, and the presence of particles with opposite Zeta potential.

So, choosing different plastics based on their triboelectric properties and the kinds of minerals present could substantially delay mineral buildup in pipes. Slightly-conductive plastics could also be helpful for that; some commercial plastics have anti-static additives, such as 0.03% carbon nanotubes, but that might not be sufficient for discharging the relatively low electrostatic voltages needed for very small particles to adhere.