First, many plastics are
hard to isolate from other wastes because the many
different resins used to make them are often difficult
to identify, and some plastics are composites of different
resins. For example, a plastic ketchup bottle might
have as many as six different layers of plastics bonded
together. Most plastics also contain stabilizers and other
chemicals that must be removed before recycling.
Second, recovering individual plastic resins does not
yield much material because only small amounts of any
given resin are used in each product.
Third, the inflation-adjusted price of oil used to
produce petrochemicals for making plastic resins is
low enough to make the cost of virgin plastic resins
much lower than that of recycled resins. An exception
is PET (polyethylene terephthalate), used mostly
in plastic drink bottles. However, PET collected for recycling
must not have other plastics mixed with it; a
single PVC (polyvinyl chloride) bottle in a truckload of
PET can render it useless for recycling. Despite its economic
value, only about 20% of the PET used in plastic
containers in the United States is recycled. However,
in 2007, Coca-Cola announced a goal of reusing or recycling
100% of the PET bottles it sells in the United
States.