Chemistry Reference
In-Depth Information
Petroleum-based polymers are used for different purposes and there is a
huge scale to produce these polymers. However, the increase in the price of
oil barrels and the increase of the global population's awareness of en-
vironmental issues (larger volumes of all kind of plastics in landfills, global
temperatures rising and glaciers melting) have created a propitious scenario
to produce biopolymers on a larger scale.
Polymer use from renewable sources has been widely studied in the bio-
medical field and in the packaging industries. Natural polymers are gener-
ally biodegradable, biocompatible and can be obtained at
d
n
2
r
4
n
g
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relatively
low cost.
7
A wide range of biodegradable alternatives have been proposed to mitigate
the problem.
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The raw materials used can be fully renewable, such as bac-
terial polyhydroxyalkanoates (PHAs) and polylactide (PLA) proposed by Dow-
Cargill consortium, or non-renewable materials, such as alternatives from
Showa Highpolymer (Japan) and BASF. The main precursors for the syn-
thesis of the latter polymers may be potentially produced through microbes
in the near future, using renewable raw materials. Bacterial poly-
hydroxyalkanoates are a polymer class studied extensively and they have
biodegradability characteristics besides being renewable. Silva et al. (2007)
also state that two components are crucial for biopolymers to become
competitive in the packaging market: the cost of raw materials and energy
and the capital investment needed to build an industrial production plant.
Once biopolymers are biodegradable, they are well regarded by environ-
mentalists. When compared to traditional polymers, biopolymers are
derived from a renewable carbon source (sugarcane, corn, potato, wheat and
sugar beet, or a vegetable oil extracted from soybeans, sunflower, palm or
other oleaginous plant). Despite this advantage of biopolymers compared
to traditional polymers, anaerobic biodegradation of many natural bio-
polymers can lead to methane and hydrogen sulfide (H
2
S) formation.
Methane is a stronger greenhouse gas than carbon dioxide (CO
2
) and it is
slower to be reabsorbed by natural processes than CO
2
.
Biodegradable materials do not present a risk of environmental impact if
these materials can biodegrade completely within six months. The rule was
established, but this does not usually occur with many biopolymers. The CO
2
resulting from burning or biodegradation of these materials is renewable
and enters the carbon mass balance in the environment, however, methane
and other gases can accumulate easily. This shows us that using bio-
degradable materials does not stop the need for rational and conscious
usage, focused on recycling, reuse and rational disposal.
Biopolymers, however, present numerous advantages: (i) they are bio-
degradable, (ii) they are biocompatible (they can be used on the human body
as prostheses, implants etc.), (iii) they can be produced by some euents
and industrial by-products, particularly from the food industry, (iv) biopo-
lymer production takes into account environmental issues, (v) they have a
wide range of applications and properties, (vi) production costs have been
decreasing as a result of the current interest from the environmental area
.
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