Technology of photodegradable plastics

Degradable plastics can be manufactured by a variety of processes [10]. An early approach to the problem was to add oxidation accelerators such as ben-zophenone to make unstable plastics. As the technology developed, more sophisticated systems were devised since packaging materials must not only degrade, but must do so at a controlled and predictable rate. A number of these systems have also been described. 

The Ecolyte process [11] developed at the University of Toronto involves inclusion in the backbone of the chain of a polymer, of a group of the general structure 

The type I process gives two free radicals, one polymeric and one small acyl radical. The polymeric radical can undergo a rearrangement known as )S-scis-sion which results in a break of a C—C bond in the backbone of the polymer and a consequent reduction in molecular weight. The type II reaction, however, is the major photodecomposition process that causes chains to break. In the presence of oxygen, both radical sites can induce photooxidation processes which cause chain degradation over a longer time scale. 

The critical portion of the sun s spectrum, between 290 and 330 nm is called the erythmal region and is the radiation responsible for tanning and sunburn of the human skin. 

The other factor which is important is that ordinary window glass filters out the erythmal radiation of the sun. 

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