*2.2. Blends Preparation*

Blends containing PLA, PBAT, and GR were prepared with different compositions, which are summarized in Table 1. The percentage of PBAT in the PLA matrix was fixed at 20 wt.% based on results reported in the literature [22]. At this percentage, PLA-20%PBAT blends have given interesting results in terms of toughness. To study the effect of the resin in the PLA/PBAT blends, the content of gum rosin added was set from 0 to 20 phr (parts of GR per hundred parts of PLA/PBAT blend). Neat PLA, neat PBAT, and PBAT with 10 phr of GR were also prepared to compare their properties with the previous blends.


**Table 1.** Composition and coding of PLA/PBAT/GR studied blends.

All materials were dried at 50 ◦C for 48 h in an air circulation oven before processing. After, the formulations were premixed in a zipper bag. To obtain the final materials, the procedure was followed as described: (1) extrusion of the material formulations in a twin-screw extruder (Dupra S.L, Castalla, Spain), L/D ratio of 25, with a temperature profile from 185 to 140 ◦C (from die to hopper) at 50 rpm; (2) milling into pellets; and (3) injection molding in an injection molding machine (Sprinter-11, Erinca S,L., Barcelona, Spain), with a temperature profile from 185 to 175 ◦C, to obtain test specimens. The test specimens were standard rectangular specimens (80 × 10 × 4 mm) and standard tensile specimens "1BA" (length ≥ 75 mm, width 10 mm, and thickness ≥ 2 mm) according to ISO 527 [41]. The films of each formulation were further obtained by the solvent casting method, using chloroform as solvent. In particular, 20 g of each formulation was dissolved in 100 mL of chloroform and heated at 30 ◦C under vigorous stirring for 1 h. The obtained solutions were cast onto a 20-cm diameter mold and the films were obtained after complete solvent evaporation at room temperature after 24 h.
