Role of ultraviolet absorbers (UVA) and hindered amine light stabilizers (HALS) in ABS stabilization

Abstract

The present work evaluates the combination effect of hindered amine light stabilizers (HALS) and ultraviolet absorbers (UVA) on the ultraviolet (UV) stability of acrylonitrilebutadiene- styrene (ABS). Thus, two types of light stabilizers, Tinuvin P and Chimassorb 119 FL, were used to improve the ABS endurance against UV. Stabilized ABS samples were submitted to accelerated weathering in a Xenontest 150 S chamber, according to standard methods, in order to predict copolymer lifetime within a commercially acceptable time period. Infrared spectroscopy with attenuated total reflectance accessory (FTIR-ATR) was used to follow chemical modifications that occur on the material surface as a consequence of degradation process. While non-stabilized ABS samples loose the butadiene component in the first 22 h of exposure, in stabilized samples submitted to same accelerated conditions this component only disappears after 150 h of exposure. Non-stabilized and stabilized ABS samples present a similar yellowing behavior, a gradually increase with exposure time. Nevertheless, as expected, color modifications are less pronounced for stabilized ABS samples. The results obtained suggest that a better performance was achieved for stabilized ABS samples with Tinuvin P and Chimassorb 119 FL, which is very important to extend the copolymer lifetime.