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Bioplastics 2016
November 10-11, 2016
Volume 7 Issue 6(Suppl) J Bioremediat Biodegrad
ISSN: 2155-6199 JBRBD, an open access journal
conferenceseries .com
November 10-11, 2016 Alicante, Spain
International Conference onSustainable Bioplastics
J Bioremediat Biodegrad 2016, 7:6(Suppl)
Degradation of PLA during long-term storage
Nikola Kocić
German Plastics Center SKZ, Germany
The degradation of PLA proceeds through hydrolysis of the ester linkages in the polymer backbone. This leads to a significant
reduction of molecular weight and thus to a deterioration of mechanical properties. However, up to now there are no
studies of PLA-hydrolysis performed under practical conditions and long-term storage. In this work, the influence of molecular
weight, granule size, crystallinity, air humidity and temperature on the hydrolytic degradation of PLA was investigated. Two
commercially available PLA types with different molecular weights were used in this study. Three different granule sizes were
prepared through compounding with a co-rotating twin-screw extruder. The granules were annealed at defined temperatures
so that crystallinity degrees in three different magnitudes were generated. Finally, all granules were stored at five different
temperatures in the range from 10 to 50º C and a relative humidity of 33 and 75 % for six months. During this time, the viscosity
of the samples was monitored with a rotational rheometer. A simple linear function was used to define the relationship between
the weight average molecular weight and the zero viscosity in logarithmic form. By fitting the zero viscosity in the simplified
kinetic equation, the degradation rate constants for each sample at each temperature were determined and used afterward in
the Arrhenius equation to calculate the activation energy of the hydrolytic degradation for each sample. As most significant
influences on the hydrolytic degradation of PLA, temperature and air humidity were identified. The degradation rate constants
and therefore the rate of the hydrolytic degradation, increase significantly with increasing temperature and air humidity.
Furthermore, small granules, high crystallinity and high molecular weight increase the activation energy and thus reduce the
rate of PLA degradation during the long-term storage.
Starch-Yerba mate films - Biodegradability, antioxidant and plasticizing effect of yerba mate extract on
cassava starch edible films
Lucía Famá
University of Buenos Aires, Argentina
Packaging has a key role in containing and protecting food since it is highly manipulated by producers and consumers.
However, packaging materials are one of the main solid wastes in major cities of the world. Cassava starch constitutes a
useful alternative to develop eco-friendlymaterials to replace that frompetroleumdue to its advantages such as biodegradability,
low cost and availability. The incorporation of additives from natural sources into starch films is a new strategy to improve the
shelf-life of food products and the functionality of a packaging. In this sense, antioxidants (yerba mate extract), proteins (from
lentil) and micro/nano fillers (from lentil and starch) were investigated because the important properties that they can transmit
to a food product such as antioxidant, anti-inflammatory and anti-mutagen, or protean effects, and as reinforcement of food
packaging. Starch-glycerol films with antioxidants and protein presented improvements in the strain at break, showingmaterials
with more flexibility, as a typical behavior of a plasticized film. The plasticizing effect of these additives was also confirmed
from water vapour permeability, thermogravimetric and mechanic dynamic properties. The use of lentil microparticles and
starch nanoparticles showed significant reinforcing effect. The effects observed on cassava starch based films, derived from
the incorporation of antioxidants, protein and particles, makes us to think about the different potential uses of these films
as coating and/or packaging of food products in order to retard their oxidation, avoid chipping or cracking during handling,
increase their shelf life, and/or as reinforcement of their cover.