Photo-oxidation stabilization of polystyrene by aromatic ultraviolet light absorbers forming charge transfer complexes (original) (raw)

The aim of this work was to investigate the influence of UV light absorbing additives on the rate of ultra violet light initiated degradation of polystyrene (PS) in solutions. Anthracene (ANT), chloranil (CA) nitrobenzene (TNB) which can form cnarge transfer complexes between each other were used. It was found for illuminated PS-solutions by light of X=254 nm that independently of the screening efficiency of these compounds, the formed CT complexes ANT-CA and ANT-TNB cause a decrease of the rate constant of degradation and of the value of the number average of cnain scission S. This effect is due to the energy transfer from the excited polymer chain segments to the low energy triplets of these CT-complexes thus hindering the rection of polymer chain segments with oxygen leading to slowing down of photodegradation.