Biodegradable trays of thermoplastic starch/poly (lactic acid) coated with beeswax

Biodegradable trays of thermoplastic starch (TPS)/poly (lactic acid) (PLA) blends were produced by flat extrusion, calendering, and thermopressing. The trays were coated by immersion in beeswax (BW) emulsion (1, 2, and 3 g BW/100 g ethyl alcohol + Tween 80 solution) to improve their barrier properties. The trays coated with 1% BW had the higher tensile strength (11.5 +/- 1.0 MPa), and the lower solubilization capacity in water (22.8 +/- 0.8%) and trays coated with higher BW content emulsion decreased their tensile strength, stiffness, and water vapor permeability (from 7.9 to 0.2 x 10(-11) g/m.s.Pa). It was possible to produce TPS/PLA biodegradable trays by flat extrusion, calendering and thermopressing, with adequate mechanical properties and processability to be produced in large scale. The coating with beeswax is an interesting technique for reducing the water vapor permeability of hygroscopic biodegradable materials.