Photo-biodegradable polymers biodegradation studies

S-G photo-biodegradable polyethylene is now being used in a different way to reduce the pollution of water courses by fertilisers. By encapsulating the fertiliser in porous photo-biodegradable capsules fertiliser release times can be achieved from 40 days to one year. Nitrogenous fertiliser based on this principle are manufactured by Chisso-Asahi Fertilizer Company of Japan and scientific studies by Kawai of Okayama University have shown (personal communication) that the empty polymer capsules biodegrade rapidly in soil. 

Torikai A, Kato H, Fueki K, Suzuki Y, Okizaki A, Nagata M (1993) J AppI Polym Sci 50 2185 Andrady AL, Accelerated environmental exposure. Laboratory testing, and recyclability study of photo/biodegradable plastics . Final Report to USEPA under Contact 68-02-4544 Task 11-60. January 1991. 

In the photoageing of polycarbonates, photo-oxidation has been shown to be a more important process than the photo-Fries reaction. The photo-oxidation of epoxy-resins has been found to depend on the type of hardener and its concentration. A correlation has been observed between the changes in chemical structure and thermally stimulated current of poly(vinyl alcohol) during photo-oxidation. Other studies of interest include the weathering of polymers outdoors,effect of ozonation on polymers, effect of drawing, effect of biodegradation, and changes in mechanical properties of thermoplastics. ... 

Unsaturated carbon-chain polymers e.g. the polydiene rubbers discussed above) are very susceptible to peroxidation and hence biodegradation. Some of these have been studied as photodegradable polymers in their own right. For example 1,2-poly (butadiene) is a plastic with properties similar to the polyolefins. In unstabilised form it photo-oxidises and thermooxidises rather too rapidly to be very useful commercially. 

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