2. BIOPOLYMER
Biopolymers refers to the material that are either
biodegradablederived renewable and non renewable
resources(according to ASTM D 6400 99 & EN 13432) or the materials
are non biodegradable and derived from renewable resources(ASTM D
6866)
Biopolymers can be divided into to two main
groups . One group contains the biodegradable
polyesters, which are petroleum based, but they are
biodegradable. The other group contains polymers
from renewable resources, like thermoplastic starch
or poly-lactic-acid (PLA). Both TPS and PLA can
be produced from common, natural resource, and
they are readily biodegradable.
Biodegradable polymers are defined as those that undergo
microbially induced chain scission leading to the
mineralization.
3. POLY LACTIC ACID (PLA)
Polylactic acid or polylactide (PLA) is a thermoplastic aliphatic
polyester derived from renewable resources, such as corn
starch , tapioca roots, chips or starch or sugarcane . In 2010, PLA
was the second most important bio plastic of the world in regard to
consumption volume.
PLA has a crystalline of around 37%, a glass transition
temperature between 60-65 °C, a melting temperature
between 173-178 °C and a tensile modulus between 2.7-
16 GPa
6. STARCH
The glycerol and water plasticized starch was
processed in a twin screw extruder and then with
an injection moulding machine to produce TPS
products.
Starch has a granular structure,
which is built by two main carbohydrate polymers:
the linear amylose and the highly branched
amylopectin.
Plasticizers like glycerol or water have to be
used while processing, because of the low decomposition
temperature of the granular starch.
