This study shows that native starch can be easily granulated
with the use of an intensive mixer. During the granulation process,
added glycerin and water (present in starch) act as a binder, then
during extrusion of starch glycerin and water act as plastifying
agents. Granulated starch has a higher bulk density compared to
powder. Dense granules are easier for the storage and dosage compared
to powders, which is important from a technological point of
view. Increase of flowability properties of granulated starch (compare
to non-granulated powder) and elimination of dust was very
helpful during dosing into extruder feed zone.
Reactive extrusion of native starch with the presence of a plastifying
agent is the only way to obtain amorphous homogeneous
material in continuous process. The fine and uniform dispersion
of the TPS in the PE matrix is not only the result of the use of a
co-rotating twin screw extruder (intensive mixing) but also the
result of using the PE-g-MA copolymer as a compatibilizer.
Depending on the amount of starch we can obtain the nonbiodegradable
material or partially biodegradable material. Thanks
to the use of starch we can reduce the use of crude oil and increase
the use of renewable resources for polymer composite production.
Further investigations on that field should be focused on optimization
of granulation process, starch modification with use of
other plastifying agents, modification of obtained blends by filling
with natural fillers like wood flour or natural fibers, searching for
new methods of compatibilization.