Triboelectric Effect

In solid materials the nuclei tend to remain close to fixed positions, whereas some of the electrons may move quite freely. When an object is neutral, it contains equal amounts of positive and negative charge. The charging of a solid object by rubbing can be explained by the transfer of electrons from one object to the other.

Macroscopic objects made of conductive chemical elements can more or less easily (depending on the element) take on or give off electrons, and then maintain a net negative or positive charge indefinitely. This can easily be produced by rubbing two dissimilar materials together, such as rubbing amber with fur or glass with silk. In this case, there is a transfer of electrons from one material to the other material. This causes one object to become positively charged (the electron loser) and the other object to become negatively charged (the electron gainer).

A triboelectric phenomenon is a type of contact electrification in which certain materials gain an electric charge when they come into contact with another material by friction. Most of the static electricity we encounter every day is caused by the triboelectric effect.

Mechanisms on Triboelectric Effect

Although we are talking about friction, it is enough for both materials to come into contact and transfer electrons. After contact, a chemical bond is formed around some parts of the two surfaces and the charge is transferred from one object to another in order to balance the electrochemical potentials. This creates an overall charge imbalance between the two objects. When separated, some binding atoms tend to hold extra electrons and others try to get rid of electrons, although the imbalance will be partially eliminated.

The triboelectric effect is now considered to be related to the phenomenon of adhesion, where two materials composed of different molecules tend to stick together because of attraction between the different molecules. At least one of the surfaces has a high resistance to electric current (and is therefore an electrical insulator). The friction of the two materials greatly increases the effect due to the frequent contact and separation of these materials. For materials with a rugged surface, friction can cause heating, which causes either a charge transfer to be multiplied or an existing polarity to be reversed. Because the electron transfer between molecules in the different materials is not immediately reversible, the excess electrons in one type of molecule remain left behind, while a deficit of electrons occurs in the other. Thus, a material can develop a positive or negative charge that dissipates after the materials separate.

Electrostatic Discharge

An electrostatic discharge, abbreviated as ESD, is a sudden and short-term electric current between two objects with different electric potentials. A spark is triggered when the electric field strength exceeds approximately 4–30 kV/cm — the dielectric field strength of air. 

An example of an electrostatic discharge in nature is lightning. Also, you have probably experienced static electricity when combing your hair or when taking a synthetic shirt from a clothes dryer. And you may have felt a shock when you touched a metal doorknob after sliding across a car seat or walking across a nylon carpet. Electrostatic discharge is a serious problem in technology, especially with electronic components, especially in integrated circuits. Even in an imperceptible moment, the circuit can be destroyed by its mere contact with another object with a different electrical potential. 

On dry days, static electricity is much more noticeable since the air contains fewer water molecules to allow leakage. Usually, the charge leaks off onto water molecules in the air. This is because water molecules are polar — that is, even though they are neutral, their charge is not distributed uniformly. Thus the extra electrons can leak off from charged surface into the air because they are attracted to the positive end of water molecules. A positively charged object, on the other hand, can be neutralized by the transfer of loosely held electrons from water molecules in the air.

Connection to the ground also limits the build-up of static electricity when handling flammable products or electrostatic-sensitive devices. Various antistatic devices are designed to ensure the safe grounding of the electrostatic charge. For domestic handling, for example, contact with metal gas pipes, water pipes or metal pipes and central heating radiators can be used for discharge; however, plastic wiring does not allow this. 

An antistatic wrist strap, ESD wrist strap, or ground bracelet is an antistatic device used to safely ground a person working on very sensitive electronic equipment, to prevent the buildup of static electricity on their body, which can result in ESD.