Degradation of polymeric materials exposed to corona discharges

A study of polymeric materials exposed to corona discharges is presented. A needle-plate electrode system was used to generate a corona discharge and the degradation of silicone rubber (SR) and ethylene vinyl acetate (EVA) copolymer specimens was investigated. After the corona discharge treatment, physicochemical analyses of the aged specimens were carried out using Fourier transformed infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Obvious cracks and mechanical damage caused by corona discharges appeared on the surface of the aged specimens. Hydrophilic OH groups, which are byproducts of aging, were formed instead of hydrophobic CH groups on the surfaces of SR and EVA aged by corona discharges, resulting in the reduction of the hydrophobicity of the materials.