2.2.1. Preparation of Composites

Before processing, TPS and ASP were dried separately for 4 h at 60 ◦C and 24 h at 105 ◦C, respectively, in a SLW 115STD INOX air-circulating oven from POL-EKO (Wodzisław Sl ˛aski, Poland) to minimize its moisture and to avoid hydrolytic reactions [ ´ 11].

A composite of starch-based polymer with ASP was developed using a BERSTORFF ZE26 × 44D-BASIC co-rotating twin-screw extruder (26:44 L/D). Before feeding the material into the extruder, a manual pre-mixing of the different components, Mater-Bi® EI51N0/ASP/ELO, was carried out and fed into the extruder through the main hopper. The ratio of TPS/ASP was set at 20 wt% since this content has shown balanced mechanical properties and appealing aesthetics in a previous study dealing with TPS biocomposites [12]. ELO was added at 10 parts per hundred resin (phr) of biocomposite. The temperature profile was set as follows: 130-185-185-185-185 ◦C (from feeding zone to die). The rotating speed was 80 rpm. The extruded material was finally pelletized using an air knife.
