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

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 con stant electric energy to generate a corona discharge, the modification powe r decreases as the distance from the center of surface (the point on the fi lm immediately below the point electrode) increases and that the corona dis charge in a point-to-grid system can modify the him surface over a wider ar ea than in a point-to-LDPE system without grid; (2) with a constant dischar ge 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 e lectric energy used to generate a corona discharge (the yield) is inversely proportional to the point-to-grid gap. However, in a positive corona disch arge, the yield did not reach zero when the point-to-grid gap was extrapola ted 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 tempera ture increases at the plain electrode (anode) and varies with the energy di ssipated by neutral activated species. (C) 2000 Elsevier Science B.V. All r ights reserved.