Effect of graphene nanoplatelets on the dielectric permittivity and segmental motions of electrospun poly(ethylene-co-vinyl alcohol) nanofibers

The influence of the addition of graphene nanoplatelets (GNPs) on the intra/inter – molecular segmental motions of poly(ethylene-co-vinyl alcohol) (EVOH) was assessed by means of dielectric thermal analysis (DETA). The relaxation spectra were studied in terms of the dielectric permittivity (ε′) and the dielectric loss tangent (tan δ) at wide ranges of frequency (from 10−2 to 107 Hz) and temperature (from -150 to 140 °C). Two relaxation zones were disthinguished. Below the glass transition temperature (Tg), two β-relaxations were observed, which are characteristic local modes of mobility of the EVOH side groups, and related to the influence of the different surroundings of ethylene or vinyl alcohol units. At higher temperatures, the dielectric α-relaxation in the vicinities of the glass transition of EVOH was determined. The thermal activation of the β-relaxations was explained by an Arrhenius model, and showed activation energies (Ea) around 55 and 80 kJ·mol−1. The α-relaxation was explained by the Vogel-Fulcher-Tammann-Hesse (VFTH) model. The study of the segmental dynamics showed an increase in the dynamic fragility parameters with the addition of GNPs. The permittivity was increased at preferential concentrations of GNPs. In particular, the addition of GNPs up to 0.5 wt% increased the dielectric permittivity of the electrospun EVOH/GNPs nanocomposite fibers, specially at low frequencies.The authors would like to thank the European Regional Development Funds (ERDF) and the Spanish Ministry of Science, Innovation, and Universities (MICIU) for the concession of the Research Projects ENE2017-86711-C3-1-R and RTI2018-097249-B-C21. The UPV authors would also like to thank the Chilean Economic Development Agency (CORFO) the economic support in the frame of the project 13CEI2-21839. This research was also funded by the EU H2020 YPACK (773872) and USABLE (BBI-JTI-2018-836884) projects. Torres-Giner is a recipient of a Juan de la Cierva—Incorporación contract (IJCI-2016-29675) from MICIU. Universitat Politècnica de València is acknowledged for the post-doctoral aid for R. Teruel-Juanes, under the PAID-10-19 SUB.1 SP20190049 scholarship.Peer reviewe

Effect of graphene nanoplatelets on the dielectric permittivity and segmental motions of electrospun poly(ethylene-co-vinyl alcohol) nanofibers

[EN] The influence of the addition of graphene nanoplatelets (GNPs) on the intra/inter ¿ molecular segmental motions of poly(ethylene-co-vinyl alcohol) (EVOH) was assessed by means of dielectric thermal analysis (DETA). The relaxation spectra were studied in terms of the dielectric permittivity (¿¿) and the dielectric loss tangent (tan ¿) at wide ranges of frequency (from 10¿2 to 107 Hz) and temperature (from -150 to 140 °C). Two relaxation zones were disthinguished. Below the glass transition temperature (Tg), two ß-relaxations were observed, which are characteristic local modes of mobility of the EVOH side groups, and related to the influence of the different surroundings of ethylene or vinyl alcohol units. At higher temperatures, the dielectric ¿-relaxation in the vicinities of the glass transition of EVOH was determined. The thermal activation of the ß-relaxations was explained by an Arrhenius model, and showed activation energies (Ea) around 55 and 80 kJ·mol¿1. The ¿-relaxation was explained by the Vogel-Fulcher-Tammann-Hesse (VFTH) model. The study of the segmental dynamics showed an increase in the dynamic fragility parameters with the addition of GNPs. The permittivity was increased at preferential concentrations of GNPs. In particular, the addition of GNPs up to 0.5 wt% increased the dielectric permittivity of the electrospun EVOH/GNPs nanocomposite fibers, specially at low frequencies.The authors would like to thank the European Regional Development Funds (ERDF) and the Spanish Ministry of Science, Innovation, and Universities (MICIU) for the concession of the Research Projects ENE2017-86711-C3-1-R and RTI2018-097249-B-C21. The UPV authors would also like to thank the Chilean Economic Development Agency (CORFO) the economic support in the frame of the project 13CEI2-21839. This research was also funded by the EU H2020 YPACK (773872) and USABLE (BBI-JTI-2018-836884) projects. Torres-Giner is a recipient of a Juan de la Cierva-Incorporación contract (IJCI-2016-29675) from MICIU. Universitat Politècnica de València is acknowledged for the post-doctoral aid for R. Teruel-Juanes, under the PAID-10-19 SUB.1 SP20190049 scholarship.Badia, JD.; Teruel Juanes, R.; Echegoyen, Y.; Torres-Giner, S.; Lagarón, JM.; Ribes-Greus, A. (2021). Effect of graphene nanoplatelets on the dielectric permittivity and segmental motions of electrospun poly(ethylene-co-vinyl alcohol) nanofibers. Polymer Degradation and Stability. 183:1-9. https://doi.org/10.1016/j.polymdegradstab.2020.109404S1918