Photodegradation packaging plastics

This degradation reaction, supplemented by various subsequent oxidation steps, has found renewed interest in the form of the introduction of photodegrad-able plastics as part of the campaign to reduce plastic litter from throwaway packaging. Although as yet there has been no demand for photodegradable mb-bers, the incorporation of a small percentage of a vinyl ketone into a rubber copolymer or homopolymer would open the way to a useful synthesis of block copolymers. 

This chapter will try to make users aware of the various glasses, filters, and containers (glass and plastic) encountered in normal processing, packaging, and dosing and day-to-day life of pharmaceuticals. Hopefully, this information will allow one to better design and protect materials, products and users from substances that may be photodegradable. 

One of the primary methods used for protecting liquid and solid photolabile pharmaceuticals and preparations from photodegradation is to package them in colored glass or plastic. Colored/pigmented containers are also suitable for the photostabilization of sterile preparations, such as eye drops. 

Recently it has been shown that photodegradable pol3rmers suitable for use in packaging applications can be prepared by copolymerization of etiiylene or styrene witii vinyl ketone monomers (1). Since PVC is the third important plastic used for packaging, we have investigated the possibility of using the same method to develop photodegradable PVC compositions. 

The deliberate introduction of carbonyl groups into polymers, either in the main chain by copolymerization with carbon monoxide or in the side chains by copolymerization with vinyl ketones, is the basis of at least one type of plastic designed to photodegrade rapidly in outdoor exposure (115). These copolymers are widely used in the United States for the six-pack ring packaging of soft drinks, whose damaging effect on marine life has been of great concern. 

Potential uses for photodegradable polymers, such as E/CO, will exist wherever plastics littering occurs. It has been estimated that almost a billion pounds of plastics find their way into the world s waterways annually [23]. Because E/CO floats and maintains much of its photodegradability when in water, there should be commercial opportunities for E/CO in marine packaging, fishing gear, and similar applications. 

The success of this product in reducing litter suggests the need for other types of photodegradable plastics for the manufacture of highly litter-prone packages. 

The first is to incorporate photosensitive groupings in the polymer backbone. The introduction of carbonyl, the product normally produced by hydroperoxide breakdown has been investigated by Guillet and his co-workers and some success has been reported. The same economic arguments apply to a tailor-made photodegradable plastics as applies to a biodegradable plastics that is, it will cost very much more than the common packaging materials. 

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