Effects of contact method on the characteristics of surface charging of low density polyethylene

Low density polyethylene (LDPE) laminate was employed as test sample to investigate effects of contact method on surface charging behavior. A couple of parallel aluminum plates that were directly pressed on sample surface made un-intimate contact pattern, while two copper foils that were attached on the surface made the intimate contact pattern. The voltage of -8 kV was applied between the electrodes for 80 minutes, during which the charge density was measured by an electrostatic probe every 20 minutes. Obtained results show the dependence of the charging behavior upon the contact method. For the case of un-intimate contact, negative charges are accumulated on the surface. For the case of intimate contact, both negative charges and positive charges are deposited on the surface. Furthermore, the number of negative charge for the case of un-intimate contact is larger than that for the case of intimate contact.