**4. Conclusions**

In this work, PLA-PBAT blends were melt-blended and compatibilized through the incorporation of gum rosin. An improvement in both tensile and impact toughness was observed when adding gum rosin (GR) to the formulation composed of a PLA matrix with 20 wt.% of PBAT as a 'soft' component. Such increment is due to the coalescent effect of the PBAT domains into the PLA matrix due to the plasticizing effect of GR. The flexural modulus was also improved and the tensile strength increased by 80% compared to the PLA/PBAT formulation. Morphologically, it was observed that the size of the PBAT domains of 2–3 µm was optimal to reduce stress concentrations in impact conditions. Concerning neat PLA, a significant reduction of up to 8 ◦C of the melting temperature and up to 5.3 ◦C of the glass transition temperature was observed, which denotes an improvement of the processability of PLA in the blends containing PBAT and GR. Regarding the application of the obtained blends as films for packaging, PLA-PBAT-GR films were transparent with luminescence (L\*) values very close to neat PLA; therefore, all the films obtained presented a very good visual appearance for the intended use. Moreover, improved barrier properties were observed as a reduction in OTR\*e of up to 35% compared to the PLA/PBAT blend film and additionally showing an increase in hydrophobicity, as an increase in the water contact angle value from 67.2◦ for PLA to 74.5◦ for the PLA/PBAT\_10GR film formulation was observed. Finally, the obtained results show that GR can be used as a dispersed phase size control agent to improve the toughness of PLA/PBAT formulations. The results obtained demonstrate the potential of the PLA/PBAT/GR films to be produced at an industrial level and further used in the food packaging field to replace traditional non-biodegradable plastics.

**Author Contributions:** Conceptualization, M.A., J.M.F., M.P.A., and J.L.-M.; data curation, M.A., J.M.F., D.L.M., L.P., M.P.A., and J.L.-M.; formal analysis, M.A., J.M.F., M.P.A., and J.L.-M.; funding acquisition, J.L.-M.; investigation, M.A., J.M.F., and M.P.A.; methodology, M.A. and J.M.F.; project administration, M.P.A. and J.L.-M.; resources, J.L.-M.; supervision, D.L.M., L.P., M.P.A., and J.L.-M.; validation, M.A., J.M.F., D.L.M., L.P., M.P.A., and J.L.-M.; visualization, M.A., J.M.F., D.L.M., L.P., M.P.A., and J.L.-M.; writing—original draft, M.A., J.M.F., and M.P.A.; writing—review and editing, M.A., J.M.F., D.L.M., L.P., and M.P.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Spanish Ministry of Economy and Competitiveness (MINECO), project: PROMADEPCOL (MAT2017-84909-C2-2-R).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Acknowledgments:** M.A. thanks Secretaría de Educación Superior, Ciencia, Tecnología e Innovación (SENESCYT) and Escuela Politécnica Nacional (EPN). J.M.F. thanks the postdoc contract (APOSTD/2019/122) Generalitat Valenciana (2019-2021).

**Conflicts of Interest:** The authors declare no conflict of interest.
