**4. Conclusions**

PLA/lignin biocomposites with di fferent lignin loading were prepared and characterized in detail. Thermogravimetric analysis indicated that the thermal decomposition of lignin occurred over a wide temperature range. PLA/lignin biocomposites showed the highest antioxidant activity, due to the antioxidant activity of lignin. Biocomposites exhibited good extrudability and flowability with no observable agglomeration of the lignin. This suggests that lignin-containing biocomposites are plausible alternatives for 3D printing applications.

**Author Contributions:** Idea and supervision: G.C.-C.; Investigation: M.T.-O., E.E., G.C.-C., Draft preparation, reviewing and editing: M.T.-O., E.E., A.R., G.C.-C.

**Funding:** Part of this work was funded by the Research Council of Norway through the ALLOC project (grant 282310). The authors thank the COST Action LignoCOST (CA17128) for funding the short-term scientific mission of E.E. at RISE PFI and Spain's DGICyT, MICINN for supporting this research within the framework of the Projects CTQ2016-78729-R and the Spanish Ministry of Science and Education through the National Program FPU (Grant Number FPU14/02278).

**Acknowledgments:** Johnny Kvakland Melbø, Kenneth Aasarød, Ingebjørg Leirset and Cornelis van der Wijst at RISE PFI are acknowledged for valuable assistance in the laboratory work.

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