The influence of moisture on the dielectric properties of poly(ethylene-co-vinyl alcohol)

Bizet, Angeline; Nakamura, N.; Teramoto, Yoshiko; Hatakeyama, Tatsuko

doi:10.1016/0040-6031(94)87017-9

Cited by 6 publications

(5 citation statements)

References 13 publications

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“…When the conductive effects were minimized, two peaks could be recorded, that is, one prominent peak at low frequencies and a broader one at high frequencies. These peaks have been described by other authors as the α- and β-relaxations, respectively [ 37 ]. On the one hand, the α-relaxation is ascribed to the main chain segmental motion and reflects a transition from the glassy to the rubbery state, related to the so-called T g .…”

Section: Resultsmentioning

confidence: 69%

Electrospun Poly(ethylene-co-vinyl alcohol)/Graphene Nanoplatelets Composites of Interest in Intelligent Food Packaging Applications

et al. 2018

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Graphene nanoplatelets (GNPs) were synthetized from graphite powder and, thereafter, embedded in poly(ethylene-co-vinyl alcohol) (EVOH) fibers by electrospinning in the 0.1–2 wt.-% range. The morphological, chemical, and thermal characterization performed on the electrospun nanocomposite fibers mats revealed that the GNPs were efficiently dispersed and rolled along the EVOH fibrilar matrix up to contents of 0.5 wt.-%. Additionally, the dielectric behavior of the nanocomposite fibers was evaluated as a function of the frequency range and GNPs content. The obtained results indicated that their dielectric constant rapidly decreased with the frequency increase and only increased at low GNPs loadings while the nanocomposite fiber mats became electrically conductive, with the maximum at 0.5 wt.-% GNPs content. Finally, the electrospun mats were subjected to a thermal post-treatment and dark films with a high contact transparency were obtained, suggesting that the nanocomposites can be used either in a nonwoven fibers form or in a continuous film form. This study demonstrates the potential of electrospinning as a promising technology to produce GNPs-containing materials with high electrical conductivity that can be of potential interest in intelligent packaging applications as “smart” labels or tags.

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Section: Resultsmentioning

confidence: 69%

Electrospun Poly(ethylene-co-vinyl alcohol)/Graphene Nanoplatelets Composites of Interest in Intelligent Food Packaging Applications

et al. 2018

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“…Isto é consequência da natureza estrutural deste segmento constituído por um copolímero aleatório, com duas unidades diferentes em polaridade, poli(etileno) (apolar) e poli(acetato de vinila) (polar). Neste caso, a fração de poli(acetato de vinila) é a responsável pelo sinal dielétrico da fração EVA [17]. Na Figura 2 pode ser observado também que, para as misturas com 60 % e 90 % (em massa) de copolímero, o valor da T g (relaxação ) da fração de EVA não muda quando comparada à do copolímero puro.…”

Section: Espectroscopia De Relaxação Dielétrica (Drs)unclassified

Estudo da mistura do éter diglicidílico do bisfenol-A com poli(etileno-co-acetato de vinila)-g-poli(metacrilato de metila) por espectroscopia dielétrica e calorimetria exploratória diferencial

2012

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RESUMOAs curvas calorimétricas e os espectros de relaxação dielétrica correspondentes às misturas do éter diglicidílico do bisfenol-A com diferentes concentrações do copolímero poli(etileno-co-acetato de vinila)-gpoli(metacrilato de metila) (EVA-g-PMMA) foram obtidos utilizando a calorimetria exploratória diferencial (DSC), e a espectroscopia de relaxação dielétrica (DSR), respectivamente. A temperatura de transição vítrea (T g ) do segmento de PMMA aumenta com o conteúdo de copolímero na mistura. O comportamento da T g foi descrito pela equação de Gordon-Taylor, utilizando a fração mássica de PMMA. Nos espectros dielétricos, aparecem as relaxações do tipo  características dos dois segmentos moleculares. Neste caso, o aumento da concentração de copolímero provocou o aumento da temperatura de relaxação  correspondente ao segmento de PMMA, e não foi observada mudança na relaxação  para a fração de EVA. Estes comportamentos revelam que os segmentos estruturais do copolímero apresentam interações bem diferenciadas com o monômetro epoxídico. O segmento de PMMA é miscível, portanto, provocou fortes interações com a resina quando comparado à fração de EVA, que não manifestou interação aparente e originou a heterogeneidade do sistema.Palavras-chave: Miscibilidade, éter diglicidílico do bisfenol-A, copolímero graftizado, calorimetria exploratória diferencial, espectroscopia dielétrica. ABSTRACTThe calorimetric curves and the dielectric relaxation spectra corresponding to blends of diglycidyl ether of bisfenol-A with different concentration of poly(ethylene-co-vinyl acetate)-g-poly(methyl methacrylate) (EVA-g-PMMA) were obtained using differential scanning calorimetry (DSC) and dielectric relaxation espectroscopy (DSR), respectively. The glass transition temperature (T g ) of the PMMA segment of increases with the copolymer content in the blends. The T g behavior was described by the Gordon-Taylor equation, using the weight fraction of PMMA. In the dielectric relaxation spectrum,  relaxations of the two molecular segments are deserved. In this case, the increase in copolymer concentration led to the increase of -relaxation corresponding to the PMMA segment, and there was not change in -relaxation for the EVA fraction. These behaviors show that the structural segments have very different interactions with the epoxy monomer. The PMMA segment of is miscible in the epoxy resin, therefore, provoked strong interactions with the resin when compared to EVA fraction, which presented no apparent interaction and gave origin to the system heterogenity.

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“…EVOH has two characteristic relaxations which occur within the frequency range being examined here, a MWS relaxation and a β-relaxation. The cause of the MWS relaxation is addressed in the previous chapters but the β-relaxation has been suggested to likely be caused by the local relaxation of crystalline regions or the movement of hydroxyl groups which may interact with each other from one vinyl alcohol groups to another, inhibiting chain motion [6]. Despite having heavy oxidation and the samples being physically destroyed (shown in Figure 17) as a result of the accelerated weathering, no significant changes in the β-relaxation were observed; however, the thermally aged samples showed a decrease in this relaxation frequency.…”

Section: Thermal Degradation Experimentsmentioning

confidence: 99%

“…From a dielectric standpoint, information is scarce on how its permittivity changes with respect to frequency. Most of the literature is centered on the oxidation behaviors [5,6]. It has been suggested though that the β-relaxation is likely due to either the local relaxation of crystalline regions or the movement of hydroxyl groups which may interact with each other from one vinyl alcohol groups to another, inhibiting chain motion [6].…”

Section: Ethylene Vinyl Alcoholmentioning

confidence: 99%

Dielectric characterization of high-performance spaceflight materials

Kleppe¹,

Nurge²,

Bowler³

2015

AIP Conference Proceedings

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The influence of moisture on the dielectric properties of poly(ethylene-co-vinyl alcohol)

Cited by 6 publications

References 13 publications

Electrospun Poly(ethylene-co-vinyl alcohol)/Graphene Nanoplatelets Composites of Interest in Intelligent Food Packaging Applications

Electrospun Poly(ethylene-co-vinyl alcohol)/Graphene Nanoplatelets Composites of Interest in Intelligent Food Packaging Applications

Estudo da mistura do éter diglicidílico do bisfenol-A com poli(etileno-co-acetato de vinila)-g-poli(metacrilato de metila) por espectroscopia dielétrica e calorimetria exploratória diferencial

Dielectric characterization of high-performance spaceflight materials

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