325
19
ethylene terephthalate (Bio-PET). These
are so-called drop-in solutions in which the
polymerization and processing processes
of the petrochemical industry can be
largely adopted and which can thus be
quickly introduced to the market.
5 On the other hand, there are several monomers which can be produced relatively
easily from renewable raw materials, but
which supply a new polymer that was
previously not available on the market.
One example is polylactic acid (PLA) from
biogenic lactic acid (i.e. 2-hydroxypropionic
acid, 7 Chap. 6 and 7 Sect. 19.2.2).
requirements and provided with additives.
Cellulose-based and starch-based plastics,
for example, are examples of these materials
(7 Sect. 19.2.1).
5 On the other hand, monomers can be
produced from renewable sources (natural
monomers) and then chemically linked to
form polymers (i.e. polymerized). Here, too,
there are basically two subsequent classes:
5 On the one hand, those biopolymers
which represent a direct (partial) replacement of an otherwise known polymer
produced from fossil raw materials, such
as biopolyethylene (Bio-PE) or biopoly19.1 · Definition and Classifications
BOX: Radiocarbon Dating
Radiocarbon dating (also
known as the 14 C dating) can
be used to determine the age
of organic materials. It is based
on determining the ratio of the
two carbon isotopes 14 C and 12 C.
Although 14 C is radioactive and
decays, cosmic rays repeatedly
recreate 14 C in the atmosphere;
an equilibrium is formed and
the ratio in the atmosphere
is constant. All plants absorb
carbon in the form of CO 2
through photosynthesis, and
humans and animals then
consume this carbon in their
food. The same ratio of 14 C to
12 C is therefore always found
in living organisms. Only when
the organism dies and does not
take up new CO 2 , the ratio shifts
due to the decay of 14 C. The
half-life of about 5700 years and
the currently determined ratio
of a sample can then be used to
determine its age.
This dating can also be used
to determine the biogenic
origin of plastic. If the carbon
in the polymer originates from
natural sources, the 14 C/ 12 C
ratio will hardly differ from the
natural ratio. However, if the
polymer is of fossil origin (e.g.
from crude oil, which is about
200 million years old), there is
almost no 14 C left in the sample.
The result can be expressed as
a percentage of the standard:
A completely biogenic polymer
such as cellulose has a value
of 100 pmC (percent modern
carbon) and fossil resources
typically 0 pmC. In this way, a
mixture of fossil and biogenic
monomers can also be
detected in homopolymers
(i.e. those formed from a
single monomer). In this case,
values between 0 and 100 pmC
would be determined when
determining the 14 C/ 12 C ratio
in comparison to the standard
substance.
This methodology can be
applied not only to bioplastics,
but also to odors and flavorings
in foods whose natural or
synthetic origin can be
determined in this way
(7 Chap. 18).
Biodegradable plastics are of interest
because the bulk plastics (polyethylene PE,
polypropylene PP, polystyrene PS, polyvinyl
chloride PVC), which are nowadays produced
and used in large quantities, are inert to bacterial or enzymatic degradation and do not
decompose under atmospheric influences such
as sunlight. This leads to these plastics being
released into the environment and remaining
there for many years if improperly disposed
of; they are persistent. This is problematic, for
example, for the pollution of the oceans and the
animal kingdom: Fish and birds take up plastic particles with their food and cannot digest
them so that they can starve. The possibility of
composting plastics with other biological waste
is also an essential criterion in the development
of these plastics. It should be noted that specific
criteria have been defined for the biodegradability of plastics. If these criteria are fulfilled,
appropriate labels are awarded. The conditions
under which the biodegradability of these
plastics is tested (relevant for large-scale composting plants) cannot usually be achieved in
domestic compost or nature (BOX: Composting
of plastics).
19
ethylene terephthalate (Bio-PET). These
are so-called drop-in solutions in which the
polymerization and processing processes
of the petrochemical industry can be
largely adopted and which can thus be
quickly introduced to the market.
5 On the other hand, there are several monomers which can be produced relatively
easily from renewable raw materials, but
which supply a new polymer that was
previously not available on the market.
One example is polylactic acid (PLA) from
biogenic lactic acid (i.e. 2-hydroxypropionic
acid, 7 Chap. 6 and 7 Sect. 19.2.2).
requirements and provided with additives.
Cellulose-based and starch-based plastics,
for example, are examples of these materials
(7 Sect. 19.2.1).
5 On the other hand, monomers can be
produced from renewable sources (natural
monomers) and then chemically linked to
form polymers (i.e. polymerized). Here, too,
there are basically two subsequent classes:
5 On the one hand, those biopolymers
which represent a direct (partial) replacement of an otherwise known polymer
produced from fossil raw materials, such
as biopolyethylene (Bio-PE) or biopoly19.1 · Definition and Classifications
BOX: Radiocarbon Dating
Radiocarbon dating (also
known as the 14 C dating) can
be used to determine the age
of organic materials. It is based
on determining the ratio of the
two carbon isotopes 14 C and 12 C.
Although 14 C is radioactive and
decays, cosmic rays repeatedly
recreate 14 C in the atmosphere;
an equilibrium is formed and
the ratio in the atmosphere
is constant. All plants absorb
carbon in the form of CO 2
through photosynthesis, and
humans and animals then
consume this carbon in their
food. The same ratio of 14 C to
12 C is therefore always found
in living organisms. Only when
the organism dies and does not
take up new CO 2 , the ratio shifts
due to the decay of 14 C. The
half-life of about 5700 years and
the currently determined ratio
of a sample can then be used to
determine its age.
This dating can also be used
to determine the biogenic
origin of plastic. If the carbon
in the polymer originates from
natural sources, the 14 C/ 12 C
ratio will hardly differ from the
natural ratio. However, if the
polymer is of fossil origin (e.g.
from crude oil, which is about
200 million years old), there is
almost no 14 C left in the sample.
The result can be expressed as
a percentage of the standard:
A completely biogenic polymer
such as cellulose has a value
of 100 pmC (percent modern
carbon) and fossil resources
typically 0 pmC. In this way, a
mixture of fossil and biogenic
monomers can also be
detected in homopolymers
(i.e. those formed from a
single monomer). In this case,
values between 0 and 100 pmC
would be determined when
determining the 14 C/ 12 C ratio
in comparison to the standard
substance.
This methodology can be
applied not only to bioplastics,
but also to odors and flavorings
in foods whose natural or
synthetic origin can be
determined in this way
(7 Chap. 18).
Biodegradable plastics are of interest
because the bulk plastics (polyethylene PE,
polypropylene PP, polystyrene PS, polyvinyl
chloride PVC), which are nowadays produced
and used in large quantities, are inert to bacterial or enzymatic degradation and do not
decompose under atmospheric influences such
as sunlight. This leads to these plastics being
released into the environment and remaining
there for many years if improperly disposed
of; they are persistent. This is problematic, for
example, for the pollution of the oceans and the
animal kingdom: Fish and birds take up plastic particles with their food and cannot digest
them so that they can starve. The possibility of
composting plastics with other biological waste
is also an essential criterion in the development
of these plastics. It should be noted that specific
criteria have been defined for the biodegradability of plastics. If these criteria are fulfilled,
appropriate labels are awarded. The conditions
under which the biodegradability of these
plastics is tested (relevant for large-scale composting plants) cannot usually be achieved in
domestic compost or nature (BOX: Composting
of plastics).