Ultraviolet radiation surface treatment of polymers

Ultraviolet (UV) radiation in the 185 nm–280 nm (UVC) band can oxidize polymer surfaces by a combined effect of UV activation of the polymer and the production of ozone and atomic oxygen from air. UV photo-oxidation creates polar functional groups that increase surface energy and provide the thermodynamic driving force required for good wettability and adhesive performance of the polymer.; UV treatment of polycarbonate (PC), polyethylene terephthalate (PET), epoxy, and polydiene rubber was studied in detail. The changes in wettability and surface chemistry (determined by XPS) were related to the UV treatment process variables and found to depend primarily on the net irradiation. In the case of low Tg polymers, a strong effect of temperature on the surface properties was also observed. A process model is proposed to characterize the UV modification of these polymers. Sensitivity functions are used to describe the evolution of surface properties as a function of irradiation, and model parameters are related to physical and chemical properties of the polymers. The model can be extended to other polymers and ultimately used to predict the properties of polymer surfaces after irradiation by xenon arc UV lamps.