*2.1. Materials*

The poly(lactic acid) (PLA) used was IngeoTM Biopolymer, commercial-grade 6201D, supplied by NatureWorks LLC (Minnetonka, MN, USA). The pellet's density was 1.24 g/cm<sup>3</sup> , the melt flow index was 15–30 g/10 min measured at 210 ◦C, and it contained 2% of D-lactic acid. The poly(butylene adipate-co-terephthalate) (PBAT) was a commercial-grade BiocosafeTM 2003 F, supplied by Xinfu Pharmaceutical Co. Ltd. (Zhejiang, China) and it was characterized by a density of 1.25 g/cm<sup>3</sup> and a melt flow index < 6 g/10 min at 190 ◦C. As the additive, gum rosin (GR), supplied by Sigma-Aldrich (Mostoles, Spain), was used.
