. . .
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:
PETE or PET, Polyethylene terephthalate
HDPE, High-Density polyethylene
V or PVC, vinyl/polyvinyl chloride
LDPE, Low Density Polyethylene
PP, Polypropylene
PS, Polystrene
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
Plastic Factoids
from the Institute of Scrap Recycling Industries
provides a good summary of different plastics,
their characteristics and uses,
listed by recycling code.
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:
Friday, 21-Sep-2012 19:32:35 MDT
