Ask A Scientist© Environmental Science Archive

December 1991

Author:     shudson
Text:       Polystyrene foam has a bad rap. A workshop I attended gave me the 
information that Polystyrene foam is actually very reusable. Is this true?

Response #: 1 of 1
Author:     Don Libby
Text:       Sure, any material that does degrade or decompose is reusable. The 
question is whether an economically viable system for collecting and reusing 
it can and will be developed. Polystyrene foam manufacturers make money by making 
polystyrene foam, not by reusing it. Ultimately, the cost to society might be lower 
if it were collected and reused, but who will organize and pay for the effort? 
Three watch-words for controlling material consumption are "reduce"-"reuse"-
"recycle". If you cannot avoid using polystyrene foam, you might find some other use 
for it - polystyrene foam packing peanuts make pretty good drainage for potted plants 
for example. As far as recycling goes (using discarded materials as raw 
materials for producing new materials) I do not know of anyone who does it (my 
city collects glass, metal, and paper, but not polystyrene foam). I am not enough of 
a chemist to know if it is technically possible to recycle polystyrene foam, but I 
take the lack of any recycling program to be a sign that it is cheaper to make 
new polystyrene foam than it is to reuse old polystyrene foam for the immediate future. In 
the distant future, it may be economical to mine landfills to retrieve 
materials like polystyrene foam.
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Updated September 2005
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There are two common forms of polystyrene: extruded and expanded.
 
Extruded polystyrene is used for building insulation. It is strong, stable, 
and absorbs little water. It can be, and often is, reused for building 
insulation. Polystyrene foam is the brand name of extruded polystyrene manufactured 
by Dow. Unfortunately, it has become a common term for all foam plastics.

Expanded polystyrene is less dense, has less insulating value, and can 
hold water. It can also be used as building insulation (often called 
"beadboard" as it is made of polystyrene beads), but it is also used for 
coffee cups, sandwich boxes, packaging, and other disposable products.
 
Sheldon
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