Chemistry Reference
In-Depth Information
need to grow plants for food and for raw materials. Research is involved in pro-
ducing bacteria strains that require different sources of energy from plants, as well
as looking to genetically engineering a food crop with the ability to produce plas-
tics or a bio-intermediate in the stem of the plant for production of bioplastics.
Bioplastics also have the advantage of a reduced environmental impact from
disposal of used products. Bioplastics usually are biodegradable and therefore
allow the material to be cycled back into the earth. Bioplastics are the least toxic of
all plastics to the environment, as demonstrated in
Fig. 13.6
, a figure providing a
relative range of toxicity of plastics. This advantage of bioplastics is decreased
when proper disposal protocols are not followed. For instance,
landfills are
This ranking is based on
the health and environ-
mental hazards created
during production, use,
and disposal of the
listed plastics. The code
numbers are used by the
industry to identify the
major plastic resins.
Most
Harmful
PVC
#3
PS
#6
PU, PC,
ABS, TPE
PETE
#1
EVA
TPE
Metallocenes
PE #2, #4
PP #5
Least
Harmful
Bio-based Polymers
A key to the plastics and some hazards associated with production, use, and disposal
Level 1
PVC = Polyvinyl chloride
PS = Polystyrene
PU = Polyurethane
Chlorine, intermediates, many additives, byproducts
Intermediates, fewer additives, some byproducts
Some chlorine used, intermediates, waste byproducts
Hazardous intermediates, difficult to recycle
Some chlorine used, intermediates, lactic solvents, BPA
A copolymer or alloy of conventional plastic
Some hazardous chemicals, high recycling rate
Chloride catalyst, some byproducts
Fewer additives, some byproducts, high recycling rate
Fewer additives, some byproducts
Naturally based, e.g., starch. cellulose; compostable
Level 2
ABS = Acrylonitrile Butadiene Styrene
PC = Polycarbonate
TPE = Thermoplastic Elastomer
PETE = Polyethylene terephthalate
EVA = Ethyl vinyl acetate
PE = Polyethylene
PP = Polypropylene
Bio-based Polymers
Level 3
Level 4
Level 5
FIGURE 13.6
Plastics pyramid of the most harmful (top) to the least harmful (bottom) plastics. Image
taken from
[1]
.
