Photodegradation: a solution for the shopping bag 'visual pollution' problem?

DISCARDED PLASTIC BAGS POSH A 'VISUAL pollution problem as they are indiscriminately disposed of and are often brightly coloured. Enhanced photo-oxidation is a possible route to accelerate the mineralization, and hence removal, of such litter. We evaluated the effect of selected metal complexes and an antioxidant on the accelerated weathering of blown polyethylene and polypropylene films in a QUV tester, and found that the additives were more effective in polypropylene than in polyethylene. The transition metal complexes, and, in particular, ferric stearate, were very effective photo-degradants. Copper 2,4-pentanedione provided a measure of ultraviolet protection to polyethylene but not to polypropylene. Poly(1,2-dihydro-2,2,4-trimethylquinoline), a commercial antioxidant, caused accelerated UV degradation; an additional advantage is that its use as a prodegradant is not expected to affect the recyclability of the polymers adversely.