Contact Charging of Irradiated Polyethylene

Abstract

The contact charging in vacuum between polyethylene irradiated in an atomic pile and metal has been investigated. By successively bringing them into contact and then separating, the charge on polyethylene increases, at first rapidly then gradually, to its saturation. This seems to be due to an equilibrium being established by the successive transition of charge through the interface in one way in coming into contact and back in the other in separation. The saturation charge with one unit of dose (50×10⁶r) of radiation is negative, the amount of which increases at first with every additional dose, then decreases to the initial small amount at 9 units of dose and eventually becomes a small positive charge at 72 units of dose.
The saturation value varies with the work function of the metal. Hence a conclusion may be drawn that the change in the contact charge with the irradiation corresponds to the change in effective work function of polyethylene caused by formation and transition of electron trapping states in the irradiated polyethlene.