2.2. Preparation of sheets
Initially, pellets of thermoplastic starch were
produced by extrusion in concentrations of 0.25 g and
0.30 g of glycerol per 1 g of starch (TPS25 and TPS30,
respectively). The pellets of TPS and PLAwere then mixed
at a ratio of 70/30 (wt/wt) and extruded to obtain blends
of TPS25/PLA and TPS30/PLA. Both the TPS and the blends
were processed in a single-screw extruder (BGM, model
EL-25,Brazil) with 25 mm screw diameterand L/D ratio of
30.Thescrewspeedwas35rpmandthetemperaturesin
the four heating zones were 120C and150 C for
theTPSand blend processing, respectively.
For the sheet production, blend pellets were thermo-
pressed in a hydraulic press (Schulz, model PHS, Brazil) at
150C and 2.6 MPa and then cooled to room temperature.