Coded Plastic Materials

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Parts/Contexts

Every single piece of plastic

Keywords

plastic, polyethelene terephthalate, vinyl, polyvinal chloride, PVC, polypropylene, polystyrene, polyurethane, recycling

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Predecessor Patterns

. . . Garbage Separation at the Source can help lower the cost of recycling by eliminating the garbage stew that results in a single general-purpose garbage can. A special problem remains with plastics, however, that further need to be kept separate to make recycling them economically sound.

Problem Summary

Because there are so many different types of plastics, most people are unable to identify them without identifying codes.

Analysis

Do you know your polystyrene from your polyethelene, polyester, polypropylene, nylon, ABS, PVC (vinyl), or polyurethane? How about your high-density polyethelene versus your low-density polyethelene versus your polyethelene terphthalate? Have you ever accidentally melted a plastic kitchen container (like Tupperware) and noticed that the very thin portions are very much like a plastic bag? That's because both are made from polyethelene; only the density and thickness determines the rigidity of the form.

Other seemingly different plastics are actually the same. For example, modern floor tiles, foam matresses and padded dashboards in cars are all made of polyurethane. You might know some of your clothes are polyester, but did you know that's the same plastic that is used in "fiberglass"?

Most of us can't indentify the many different kinds of plastic without help, and even industrial designers and engineers who work with them are sometimes confused. This makes recycling plastics difficult, because few useful materials can be made from a mixture of different plastics.

As far back as the early 1970's it became clear to some people that there ought to be standardized codes to identify different plastics, and a law that requires their use. In the U.S. such a standard and law soon came into being. The codes, placed inside a triangular recycling symbol, are as follows:

1. PETE or PET, Polyethylene terephthalate
2. HDPE, High-Density polyethylene
3. V or PVC, vinyl/polyvinyl chloride
4. LDPE, Low Density Polyethylene
5. PP, Polypropylene
6. PS, Polystrene
7. Other Plastics

Solution Summary

Therefore:

Identify the material of every single thing manufactured from plastic with a code. The code can be embossed or printed as long as it survives its life cycle to the recycling center. The US codes are a start; an international standard is needed.

Successor Patterns

(none) . . .

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References/Sources

1. Plastic Factoids from the Institute of Scrap Recycling Industries provides a good summary of different plastics, their characteristics and uses, listed by recycling code.

Author/Date

Gary Swift, 1973; last revision August 30, 1996.

© Gary Swift, 1996. Permission to copy this pattern for academic and non-profit use is granted so long as this copyright notice is retained. To copy otherwise requires specific permission.

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