Lastly, the -C=Cvibrations of butadiene at 966 cm -1 (d) and 909 cm -1 (e) present in the unaged sample disappeared completely after weathering. This is in line with the gas chromatography that the relative amount of butadiene with respect to the pristine sample completely disappeared after 100 h of accelerated weathering. From these observations, it can be appreciated that the reactions caused by weathering, mainly involving oxygen, lead to chemical modifications that affect the surface preferentially.