Natural and accelerated weathering of Acrylonitrile-Butadiene-Styrene (ABS)

Spectroscopic methods, UV/Vis and Fourier Transform Infrared with an attenuated total reflectance (ATR) accessory, were applied to evaluate the influence of light stabilizers on ABS samples exposed to accelerated and natural weathering conditions up to 600h and 360 days, respectively. Some important differences in the formation rate of carbonyl compounds were found when comparing accelerated to natural weathering exposure. While stabilized samples exposed to accelerated weathering reveals slower formation of carbonyl groups than unstabilized ABS, the carbonyl absorption of samples exposed to natural weathering is comparable to the unstabilized ones. The behaviour of light stabilizers during natural exposure is somewhat surprising and cannot be only associated to its stabilizing effect. The disappearance of light stabilizers only after one month of exposure could be due to molecular scission of light stabilizers with consequence volatilization and diffusion of these fragments on the surface, while under acceleration conditions seems to occur by photochemical reactions. The results obtained are interesting showing that sometimes the material behavior under real weathering conditions cannot be predicted from the results of accelerated laboratory experiments.Fundação para a Ciência e a Tecnologia (FCT) - SFRD/BD/48512/200