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

Plastic bags pose a “visual pollution” problem as they have a high surface-to-volume ratio and because they are often brightly coloured. Enhanced photo-oxidation is a possible route to accelerate the mineralisation of such litter. Thus we evaluated the effect of selected metal complexes and an anti-oxidant on the accelerated weathering of blown polyethylene and polypropylene films in a QUV tester. It was found that the additives were more effective in polypropylene than in polyethylene. The transition metal complexes, particularly ferric stearate, were very effective photodegradants. Copper stearate provided a measure of UV protection to polyethylene but not to polypropylene. Poly (1,2-dihydro-2,2,4-trimethylquinoline), a commercial anti-oxidant, also caused accelerated UV degradation. This is significant as its use as a prodegradant is not expected to adversely affect the recyclability of the polymers.