CONTACT CHARGE ACCUMULATION AND REVERSAL ON POLYSTYRENE AND PTFE FILMS UPON REPEATED CONTACTS WITH MERCURY

Charge exchange measurements have been made on polystyrene and PTFE films in contact with mercury. The experiments were carried out in a purified atmosphere of nitrogen. Surface charge accumulation was observed on the polymer films upon repeated contacts. The surface charge saturation level could be altered and even reversed by using mercury samples of different purity for the contacts. Each mercury sample drove the surface charge to a characteristic saturation level, regardless of the previous contact history of the polymer sample. Surface charge densities as high as 200 nC cm-2 have been observed on polystyrene.