Packaging Applications of Polyhydroxyalkanoates (PHAs) - Polyhydroxyalkanoate (PHA) Based Blends, Composites and Nanocomposites - page 220

Regarding consumption by segment, plastic packaging leads with a de-
mand for 18million tons, followed by construction (9.55million tons),
motor vehicles (3.5million tons) and electronic equipment (2.6million
tons). 15
The main raw material for plastics manufacture is oil, but only 4% of the
world's oil and gas production is used for plastics production and 3-4% is
used as energy in the process. 16,17 The plastics industry is constantly de-
veloping, dealing with new technologies to answer new demands, and it is
no surprise that the world production of plastic reached 265million tons in
2010. 15
Plastic polymers can be classified into two distinct groups by thermal
behavior during processing: thermoplastic and thermosetting. Thermo-
plastics are moldable, as they soften when heated. This process can be re-
peated numerous times and polymer degradation is minimal. On the other
hand, thermosets are not easily moldable by heating. During processing,
these polymers are moldable but become rigid when the process is done and
they become resistant to temperature increase. Thermosetting plastics are
typically stiffer than thermoplastics. 18
The main thermoplastic polymer types are acrylic, cellulosic, ethylene
vinyl acetate (EVA), polyethylene terephthalate (PET), polyamides (nylons),
polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polycarbonate
and polypropylene (PP). 18 PET, PVC, HDPE, LDPE, PS and PP have a higher
production volume and relatively low cost. 19 The main thermosetting poly-
mer types are aminoplastics, epoxies, phenolics (phenol formaldehyde),
polyesters and silicones. 18 These polymers have a wide range of applications
and their features are very different.
Despite the many benefits that plastic brings to human society, their
residues are harmful. The large plastic volume, the huge amount of post-
consumer disposal and environmental impact caused by the improper dis-
posal of waste that is not biodegradable, are just some of the problems. In
addition, plastics can damage human and animal health, mainly because of
the additives and chemicals used in their manufacture. Regulatory instru-
ments to mitigate plastics' effects on human health and the environment
need to follow their cycle from production and use to disposal since most of
the plastic items sold (especially packaging and non-durable goods)
become residues in less than a year or after a single use (worst scenario).
However, plastic wastes are valuable raw material sources, which can be
converted into energy or other polymeric materials. 20 One of the challenges
is to increase recycling programs. About 31.04million tons of plastic waste
were produced in the United States in 2010 and only 2.64million tons were
recycled (7.6%).
There is good evidence that by increasing recycling potential, there will be
significant growth in the amount of post-consumer products that can be
recycled. 21,22 Currently, fossil fuel consumption for plastics production is
linear, from oil to disposal, but it must become cyclical, with further recovery
to become a raw material again. 17

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