having 12% D-lactide enantiomer has the properties similar to polystyrene and can
easily be processed via thermoforming. It has been effectively employed in food
packaging sector under the name Natureworks-PLA manufactured by NatureworksLLC (Blair, NB). Currently this has been in use for packaging of short shelf life
products [52].
The water vapor and oxygen barrier properties of PLA were enhanced by coating
PLA with PEO-Si/SiOx (polyethylene oxide), PCL-Si/SiOx (polycaprolactone), and
MAP; these PLA films can potentially be employed for packaging medium shelf life
products (vegetables, cheeses, fresh meat, processed meat) [53]. Also significant
improvement in oxygen barrier and water vapor properties were achieved for
number of polymers (nano-fibrillated cellulose film, PLA film, PHB, PLA-coated
board) quoted with thin layer of AlOx (25 nm) Hirvikorpi et al. [54].
2.4 Genetically Modified or Naturally Occurring
Organism-Based Bioplastics
Bacteria synthesize polymers like PHB and PHA via fermentation of starch or
glucose, and further they are extracted by using solvents like methylene chloride
and chloroform [55]. The properties of PHA like tensile strength, chain length, and
brittleness depends upon the type of microorganism, carbon source used, and the
monomer unit composition [56].
The melting point of PHAs ranges from 40 to 180
C based upon monomers
involved in synthesis. PHAs when combined with starch or other bioplastics can
effectively be used for packaging applications [57]. Poly(D-3-hydroxybutyrate)
(PHB) is one of the monomers of PHA; apart from its brittleness, it has almost
similar mechanical properties of PP [58, 59]. The huge crystalline domain is
responsible for the brittle nature of PHB, as it has high Tg and crystallinity [60].
As the melting temperature (175–180
C) of PHB is similar to isotactic polypropylene (iPP), it can be used for intermediate bulk containers and shrink packaging
[55]. Though the cost is high, it degrades in microbial environment in the shorter
period (5–6 weeks) of time giving out CO 2 and water as by-products under aerobic
condition and, under anaerobic condition, it produces methane [61].
2.5 Multilayer Film Systems
In recent times, an alternative strategy of developing multilayer film systems based
on PLA and PLA has emerged as the latest trend in improving the technological
properties of biopolymers [62].
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B. Srinivasan and G. Kulshreshtha
easily be processed via thermoforming. It has been effectively employed in food
packaging sector under the name Natureworks-PLA manufactured by NatureworksLLC (Blair, NB). Currently this has been in use for packaging of short shelf life
products [52].
The water vapor and oxygen barrier properties of PLA were enhanced by coating
PLA with PEO-Si/SiOx (polyethylene oxide), PCL-Si/SiOx (polycaprolactone), and
MAP; these PLA films can potentially be employed for packaging medium shelf life
products (vegetables, cheeses, fresh meat, processed meat) [53]. Also significant
improvement in oxygen barrier and water vapor properties were achieved for
number of polymers (nano-fibrillated cellulose film, PLA film, PHB, PLA-coated
board) quoted with thin layer of AlOx (25 nm) Hirvikorpi et al. [54].
2.4 Genetically Modified or Naturally Occurring
Organism-Based Bioplastics
Bacteria synthesize polymers like PHB and PHA via fermentation of starch or
glucose, and further they are extracted by using solvents like methylene chloride
and chloroform [55]. The properties of PHA like tensile strength, chain length, and
brittleness depends upon the type of microorganism, carbon source used, and the
monomer unit composition [56].
The melting point of PHAs ranges from 40 to 180
C based upon monomers
involved in synthesis. PHAs when combined with starch or other bioplastics can
effectively be used for packaging applications [57]. Poly(D-3-hydroxybutyrate)
(PHB) is one of the monomers of PHA; apart from its brittleness, it has almost
similar mechanical properties of PP [58, 59]. The huge crystalline domain is
responsible for the brittle nature of PHB, as it has high Tg and crystallinity [60].
As the melting temperature (175–180
C) of PHB is similar to isotactic polypropylene (iPP), it can be used for intermediate bulk containers and shrink packaging
[55]. Though the cost is high, it degrades in microbial environment in the shorter
period (5–6 weeks) of time giving out CO 2 and water as by-products under aerobic
condition and, under anaerobic condition, it produces methane [61].
2.5 Multilayer Film Systems
In recent times, an alternative strategy of developing multilayer film systems based
on PLA and PLA has emerged as the latest trend in improving the technological
properties of biopolymers [62].
116
B. Srinivasan and G. Kulshreshtha