UV AND OZONE TREATMENT OF POLYPROPYLENE AND POLY(ETHYLENE-TEREPHTHALATE)

The effects of exposure to ultraviolet (UV) light and ozone, separatel y and in combination, were investigated with respect to polypropylene (PP) and poly(ethylene terephthalate) (PET) surfaces. Three combinatio ns of UV light and ozone were studied: ozone only, UV light in air (pr oducing ozone), and W light in air (producing ozone) supplemented by a dditional ozone in the incoming air. The effect of the exposure time o f the PP and PET to each treatment was studied. The samples were analy zed by X-ray photoelectron spectroscopy (XPS) to determine the surface composition, and by dynamic contact angle to determine the water wett ability. The results showed that the effect of the treament was depend ent on the properties of the exposed polymer, with PET being more sens itive to the UV light and PP being more sensitive to the reactive spec ies in the gas. The exposure times studied ranged from 1 to 90 min. By monitoring the oxygen uptake levels, we were able to determine that s urface modification occurred within minutes. The possible reactive spe cies and mechanisms are discussed.