Coded Plastic Materials


Parts/Contexts:

Every single piece of plastic.

Keywords:

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

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 finally came into being in 1988 with the resin identification coding system, created by the Society of the Plastics Industry, Inc. The US codes were then adopted internationally as the first set of International Universal Recycling Codes, which now includes codes for batteries, paper, metals, biomatter and glass.

The resin 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 its resin code. The code can be embossed or printed as long as it survives its life cycle to the recycling center.

Successor Patterns

(none) . . .


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.
  2. Plastic Recycling Code List, with lists of properties, packaging applications and recycled products.
  3. Resin identification code at Wikipedia.
  4. International Universal Recycling Codes at Wikipedia.

Author/Date

Gary Swift, 1973. (First version advocating codes, 15 years before the SPI established them.)
30 August 1996. Web version.
04 January 2000. Removed broken links.
23 November 2008. Attibute resin codes to the SPI, add information about the International Universal Recycling Codes, and add new links.
Last updated:

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