TriboElectricity

 

When two bodies get in contact with each other there must be a charge difference, no matter how tiny due to the fact that the materials are very unlikely to have been exposed to exactly the same environmental conditions (even if of same material). This charge difference means there is a difference of electrons in the atoms, hence a difference in charge distribution that once the bodies are placed in contact some of the electrons will attached themselves to orbits of atoms where there is a lack of negative charge, they are dragged by induction to a positive charged area of the body whereby they will move onto the other material, hence achieving some equilibrium. Should the two body surfaces separate suddenly then the atoms with stronger positive bonding will keep the recently attached electrons, hence becoming less positive.
Again, the environmental conditions surrounding the event will contribute to determine de volume of the transfer. The speed and pressure of the contact, the type of the materials, the size of the charges etc… It is understood that the above phenomena will occur in bodies which could be any mix of solid and liquids, however interactions of solids and liquids with gases are not defined as able to generate static charges, except where gases are contaminated with foreign particles. Liquids and dust may produce static charges.
Protection from triboelecticity generation of charges can be effected through some materials like natural cotton, some papers and raw wood, but in fact the quality of the contact surfaces, the contact area, the speed of the rubbing and lubrication are important factors to determine the amount of charges generated. 
Some of the activities performed daily by persons which generate and accumulate charges in the bodies, there are many studies which are roughly coincidental in their findings. On average and for a low 10% to 20% of ambient relative humidity (RH) are the bigger values and for the high RH, 65% to 90% are the lower values, as follow: walking on carpet 1,500V to 35,000V; vinyl envelope: 600V to 7,000V; picking up plastic bag from table 1,200V to 20,000V; walking on vinyl floor 150V to 12,000V. Worker at bench: 700V to 6,000V. It is evident that keeping the ambient RH high is good for the reduction of charges, however electronics and equipment may esperience corrossion if this is too high.