Corona charging and potential decay on oxidized polyethylene surfaces

Insulating polymers are highly affected by static electricity, caused by many but only partially understood sources. Charged polyethylene holds charge for many days to weeks that usually goes without monitoring. Here, we describe a simple, non invasive and reliable procedure to detect and survey charge build-up and decay on PE surfaces oxidized by different procedures and characterized by contact angle and staining followed by visible reflectance spectroscopy: corona-charged samples were monitored by scanning with a Kelvin probe and mapping electrostatic potential as a function of time and position. The results show that PE oxidation largely prevents charge build-up and it contributes to faster dissipation of the acquired charge. PE oxidized with KMnO4/H2SO4 solution acquires no detectable corona charge but without harming the PE insulating power along the z-axis, normal to the polymer surface. Since the Kelvin probe technique is a non-contact and non-destructive method, it is potentially useful for monitoring polymer surface oxidation state in online, real time monitoring.