Environmental Engineering Reference
In-Depth Information
have been exploited to develop materials for eco-friendly packaging mate-
rials. However, the use of biopolymers/proteins have been limited because
of their usually poor mechanical and barrier properties, which may be
enhanced by adding discontinuous phased reinforcing compounds, form-
ing composites. Most reinforced materials have poor matrix-iller interac-
tions, which tend to improve depending on iller dimensions. When i llers
of nanodimension are used with bulk materials then the hybrid materials
are known as nanocomposites.
Several composites [3] have been developed by adding reinforcing com-
pounds to biopolymers/proteins to enhance their thermal, mechanical and
barrier properties. Most of these reinforced materials present have poor
interactions at the interface of both components. Macroscopic reinforc-
ing components usually contain defects, which become less important as
the particles of the reinforcing component are smaller. Biopolymers are
polymers that are produced by living organisms and represent a special
class of polymers that are biodegradable in nature [4]. h ey are produced
from plants from the agricultural non-food crops directly and by means
of fermentation, hence rendering them renewable. In another aspect, use
of biopolymers promotes organic recycling either through composting,
anaerobic digestion or by biomass conversion. h ese benei ts have con-
tributed to the rising signii cance of biopolymers. Some examples of bio-
polymers include polylactide acid (PLA), polyhydroxy alkanoate (PHA),
cellulose and starch-based polymers or thermoplastic starch (TPS). Despite
the biodegradability of biopolymers, there exist several factors that limit
their applications as packaging materials. First, their mechanical proper-
ties are relatively poor compared to many petroleum-based plastics due to
their inherent lower stif ness and strength, as well as brittleness. Second,
many are relatively sensitive to water, with some materials dissolving rap-
idly, or have a substantial decrease in mechanical performances when they
absorb water, especially in moist environments.
h e introduction of nanoi llers should be explored for sustainable pack-
aging as an improvement in properties could take place with the use of
less raw materials, thus conserving resources [5]. h is, in conjunction with
degradability of biopolymer, could impart ease in waste management as
well. Hence, several research groups started the preparation and charac-
terization of various kinds of biodegradable polymers/nanoi ller systems.
To date, the work carried out on biopolymeric nanocomposites has been
focused mainly on the designing and making of biopolymeric nanocom-
posites by selecting an appropriate synthetic method and adjusting their
structures and compositions [6].
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