Surface modification of LDPE by a DC corona discharge generated in a point-to-grid system: the influence of geometric parameters of the system on modification power

Abstract

We examined the influence of the geometric parameters of the system on the modification power as determined by the contact angle on the surface of the treated low-density polyethylene (LDPE). We have found that (1) with a constant electric energy to generate a corona discharge, the modification power decreases as the distance from the center of surface (the point on the film immediately below the point electrode) increases and that the corona discharge in a point-to-grid system can modify the film surface over a wider area than in a point-to-LDPE system without grid; (2) with a constant discharge current, the modification power on the center of surface decreases when the point-to-grid gap in negative corona treatment increases, but increases in positive corona treatment; (3) the modification power compared to the electric energy used to generate a corona discharge (the yield) is inversely proportional to the point-to-grid gap. However, in a positive corona discharge, the yield did not reach zero when the point-to-grid gap was extrapolated to infinity, possibly because the streamer reduces the effective point-to-grid gap and produces neutral activated species along the streamer; and (4) in a negative corona, the modification power as measured by the temperature increases at the plain electrode (anode) and varies with the energy dissipated by neutral activated species.