Characterization of coated biodegradable trays by spectroscopic techniques

Biodegradable trays of thermoplastic starch (TPS)/poly (lactic acid) (PLA) blends were produced by flat extrusion followed by thermopressing. The trays were coated by immersion in beeswax (BW) emulsion (1, 2, and 3 g BW/100 g ethyl alcohol + Tween 80 solution). The structural properties of the coated trays were characterized by Confocal Raman and Infrared spectroscopies to verify the coating-tray and TPS-PLA interactions. The characterization of the TPS/PLA biodegradable trays revealed that despite the low compatibility between starch (hydrophilic) and PLA (hydrophobic) there was interaction by hydrogen bonding between the starch and PLA carbonyl group, characterizing them as an immiscible blend. The BW showed weak interaction with PLA, but this interaction was sufficient to provide a good adhesion of the BW on the surface of the trays, reducing their hygroscopicity and enabling a commercial scale production of this biodegradable trays type.