Triboelectrification

Triboelectrification has become a hot topic for space scientists these days.
When a contact is made between the two materials, an electric charge is transferred from one material into the other material. One of the materials gains excess of the electrons where as other material losses the equal amount of elections. The first material which gathers electrons becomes as negatively charges whereas the other which loses electrons becomes as positively charges. When these materials are separated from each other, they carry their charges with each other. This charge then tries to dissipate to or combines with the earth. When there is not any conducting path that allows this process, then the charges will remain static as the static electricity. This process of charging of material through contact with each other is called as triboelectrification.
According to the triboelectric series the amount by which a material is charged through triboelectrification is dependent upon various factors in general and upon the two contacting materials in particular. It has been noted that a material can charge positive when it is in contact with any one material whereas it may charge negative when is contacted with another material.
A table may be drawn by testing a range of different materials, e.g. with every material charging as positive with respect to one above and charging as negative with respect to one below. It is referred as triboelectric series. Those materials which are widely separated in series tend to charge more strongly as against each others and those materials which are closer to each other tend to charge weakly against each others. The strength of this charge also depends upon some other factors as well, for example atmospheric humidity.