**4. Conclusions**

In this research, ChNF was isolated by using the ACC method and increasing the number of ACC passes reduced the size and increased the yield of ChNF. Isolating CNF by using the combination of TEMPO oxidation and the ACC method resulted in smaller size than that of ChNF. By blending two heterogeneous polysaccharide nanofibers, we were able to prepare ChNF–CNF composites. ChNF was well blended with CNF so as to maintain the layer-by-layer structure of the composites. The composites were so flexible that they could be bent in any direction without cracking. From the FT-IR analysis, the structure of CNF and ChNFs were confirmed in the composites. The composites showed remarkable improvement of the mechanical properties, which might be due to the reinforcement of ChNF to CNF in the composites. The composites showed almost the same thermal degradation range of the CNF. Better UV-light protection was shown at higher content of ChNF in the composites. The WVTR was slightly increased at first by the addition of ChNF up to 10% and then saturated thereafter. The WCA of the composites was rather slightly decreased by adding ChNF, and enhancing this behavior is future work. The high ChNF content showed the highest antioxidant activity in the composites. Although the CNF and ChNF had low antioxidant activities, their blended composites had increased the antioxidant activity. It is the first time a simple combination of ChNF–CNF composites fabrication showed good mechanical properties and antioxidant activities. Reinforcement of ChNF into CNF was a good selection in terms of antioxidant activity, UV protection and mechanical properties. The ChNF–CNF composite could be useful for active food packaging application.

**Author Contributions:** Conceptualization, J.K. and L.V.H.; methodology, H.C.K.; validation, L.Z. and L.V.H.; investigation, P.S.P.; resources, L.V.H.; data curation, D.H.P.; writing—original draft preparation, L.V.H.; writing—review and editing, J.K.; visualization, D.H.P.; supervision, J.K.; and funding acquisition, J.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by National Research Foundation of Korea (NRF-2015R1A3A2066301). **Conflicts of Interest:** The authors declare no conflict of interest.
