**4. Conclusions**

EVOH fibers containing GNPs were successfully prepared by electrospinning. To this end, the GNPs were firstly synthetized from graphite powder by oxidation to GO according to the Hummer's method and, then, by reduction using NH4OH. The resultant flat-like graphene nanoparticles, the so-called GNPs, were solution electrospun with EVOH to obtain nanocomposite fibers with sizes in the submicron range. The embedded GNPs were rolled up in the form of continuous layers along the EVOH fiber axis. Both morphological and Raman analyses revealed that the best GNPs dispersion was obtained for the electrospun EVOH fiber mats containing 0.5 wt.-% GNPs, while graphene is likely to increasingly agglomerate as its concentration was increased. Thermal characterization indicated that the incorporated GNPs acted as an anti-nucleant agen<sup>t</sup> for the EVOH molecules, particularly at low contents due to its improved dispersion and high interaction with the polymer matrix. Finally, the dielectric behavior of the nanocomposite fibers was studied in the frequency 10−2–107 Hz range and as a function of the GNPs content. The dielectric constant was reduced with the frequency increase, in the whole range of frequencies, while it increased for GNPs contents up to 0.5 wt.-%, supporting the well dispersion of the nanoparticles at low loadings. In addition, the nanocomposite fibers presented high σ values in the 0.1–1 wt.-% GNPs range. The electrospun mat was, finally, thermally post-treated at 158 ◦C to produce continuous and contact transparent films. Applications of the resultant electrospun nanocomposite fiber mats and possibly also films in the intelligent packaging field as, for instance, smart labels or tags can be anticipated.

**Author Contributions:** Conceptualization was devised by J.M.L.; Methodology, Validation, and Formal Analysis was carried out by S.T.-G., Y.E., R.T.-J., J.D.B., A.R.-G., and J.M.L.; Investigation, Resources, Data Curation, and Writing-Original Draft Preparation was performed by S.T.-G. and J.D.B.; Writing-Review & Editing, S.T.-G.; Supervision, A.R.-G. and J.M.L.; Project Administration, J.M.L.

**Funding:** This research was funded by the European Regional Development Funds (ERDF) and Ministry of Science, Innovation, and Universities (MICIU) project numbers ENE2014-53734-C2-1-R, ENE2017-86711-C3-1-R, UPOV13-3E-1947, and AGL2015-63855-C2-1-R.

**Acknowledgments:** S.T.-G. acknowledges the MICIU for his Juan de la Cierva contract (IJCI-2016-29675). J.D.B. and R.T.-J. also thank Generalitat Valenciana (GV) for their projects APOSTD14/041 and GRISOLIA/2012/003, respectively.

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