A comparative study of UV aging characteristics of poly(ethylene-co-vinyl acetate) and poly(ethylene-co-vinyl acetate)/carbon black mixture

摘要

In this comparative study, the effect of carbon black (CB) on the UV aging characteristics of poly(ethylene-co-vinyl acetate) (EVA) was investigated. EVA, containing 13% vinyl acetate (VA), and poly(ethylene-co-vinyl acetate)/carbon black mixture (EVA/CB), containing 13% VA and 1% CB, were aged by means of UV light with a wavelength in the vicinity of 259 nm, in air, up to 400 hr. Sol-gel analyses were made to determine the percentage gelation of both virgin and aged samples. FT-IR measurements were performed to follow the chemical changes which took place in the samples during aging. Dynamic and isothermal thermogravimetry studies were performed for determination of the thermal stabilities of virgin and aged samples. Sol-gel analysis results showed that EVA itself has a tendency to form a gel under UV irradiation. EVA/CB, however, becomes a gel to a smaller extent, comparatively, under the same conditions. As a result of FT-IR measurements, some oxidation products such as ketone, lactone and vinyl species were observed through UV ageing of EVA and EVA/CB. Thermal analysis experiments exhibited that the thermal stabilities of EVA and EVA/CB decreased, to a similar extent through UV aging.