It was only in the 1950s that plastics began to come into wide use, yet within ten years, production was rising at an unparalleled rate. World consumption is now comparable with that of all non-ferrous metals. Plastics recycling has developed steadily and is carried out on a considerable scale in many countries. There are still technical, economic and structural problems to be overcome, but the potential is vast.
Although various types of plastics may look the same, they are in fact quite distinct groups of materials of different molecular construction. So practical recycling depends critically on the ability to separate them from each other. This can be achieved most efficiently in factories where recyclable material generated in the production process is easy to segregate. Post-use plastics present problems of identification, separation and also contamination. But where sufficient volumes of readily classifiable materials are available - pallet wrapping or sacks used by industry and agriculture, for example - recycling is successfully achieved. The more expensive secondary plastics, such as those arising from computers, photo-copiers and a wide range of similar electronic equipment, are normally in considerable demand. Spectrometry is among the techniques used to ensure precise identification of those materials which, after processing, are often employed in the manufacture of new electrical and electronic equipment. Recycling changes the mechanical properties of plastics to some extent, thus for that reason alone it may not be possible to recycle large quantities of a particular type straight back into the same production process. In some sectors, prejudice against secondary materials remains a significant obstacle to wider plastics recycling, but environmental and other pressures are gradually changing attitudes.
Recovery of plastics packaging presents the greatest challenge, not least in achieving economic collection of sufficient segregated material to make recycling viable. The PET bottle, being used in increasing quantities in many countries for marketing drinks, is an excellent example of a highly-recyclable form of packaging. Polyethylene terephthalate - to give PET its full name - is a sophisticated material of great strength which is used very efficiently as a beverage container. The scope for recycling PET is enormous - provided the mass collection of used bottles can be developed at an acceptable cost.
The cost of collecting small quantities of material from a multitude of sources is a major obstacle to dynamic progress in recycling many polymers. In some countries, public policy is placing a responsibility for recovery on manufacturers and distributors of packaging and other products. This "producer responsibility" is likely to lead to increased plastics recycling because some elements of traditional commercial costs will be covered - initially by the manufacturer and distributor, but ultimately by the consumer in slightly higher product prices. Recycling of mixed plastics presents a fundamental problem of polymer incompatibility. However, the introduction of so-called "compatibilisers" which create what amount to stable polymer bridges between plastics of different molecular structure, may facilitate use of mixtures. Compatibilisers already make it possible to produce a type of plastics alloy from secondary material.
Processes continue to be developed to recover the plasticisers used in making plastics, and to use these materials as feedstock in producing quite different substances. Soiled, unrecyclable plastics have positive worth in their calorific value, and can therefore be used as a fuel.
Those pesky packing peanuts don't have much recycling potential, but they can be reused, which is even better. Many packing, shipping and moving stores will take used peanuts. Just pack them up in (recycled) plastic bags, and drop them off next time you are nearby. Suitable businesses can be located under "packaging" in the yellow pages. Typical chain stores include Mail Boxes Etc. and The Postal Annex. For a partial list of local collection sites, try the Plastic Loosefill Council at 1-800-828-2214 (24 Hours). Some peanuts are not made of plastic. If you find a peanut that looks like a cheese puff, try licking it. One type of peanut is made from vegetable starch, and dissolves almost instantly in water. These taste somewhat like rice cakes, and are just as safe in a compost bin. Disposal of large expanded polystyrene blocks (such as those protecting new equipment) is problematic. The materials are very lightweight and take little energy to produce: it is easy to end up with a net environmental loss just transporting the stuff. For most individuals recycling this material is not worth it, though future research into local small-scale reprocessing may change this. If you have large quantities of material, a list of collection sites is available from The Alliance of Foam Packaging Recyclers.