Crystallinity and dielectric relaxations in semi-crystalline poly(ether ether ketone)

Arous, M.; Amor, Ikram Ben; Kallel, A.; Fakhfakh, Z.; Perrier, Gérard

doi:10.1016/j.jpcs.2007.02.046

Cited by 74 publications

(43 citation statements)

References 49 publications

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“…The log (ε″) vs. log (f) plot at different temperatures is shown in the inset of Fig.3. The slope of the straight line lying between -0.8 and -0.98 which is nearly equal to -1 indicates that the contribution from dc conduction is predominant in the system from 423 K to 563K [14][15]. The deviation of the slope from unity could be due to space charge effects at low frequencies.…”

Section: Dielectric Studymentioning

confidence: 91%

Dielectric Relaxation, Ionic Conduction and Complex Impedance Studies on NaNo3 Fast Ion Conductor

Kumar¹

2013

IJMSA

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AC conductivity, dielectric constant, loss and electric modulus of Sodium nitrate system have been studied in the frequency range from 1Hz to 10MHz and in the temperature range from 303 K to 563 K by employing impedance spectroscopy. The frequency dependent ac conductivity follows Jonscher's universal power law. Dimensionless frequency exponent (n), dispersion parameter (A) are determined. The change over frequency independent conductivity to frequency dependent conductivity at all temperatures shows the relaxation mechanism. The variation of real part of dielectric constant with frequency shows strong dispersion at low frequencies and saturation at high frequencies. The presence of peaks in the frequency plots of dielectric loss, imaginary parts of impedance and modulus are attributed to the relaxation processes. It is also confirmed by the temperature dependence study of real part of dielectric constant. The activation energy from relaxation processes and conductivity has been evaluated.

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Section: Dielectric Studymentioning

confidence: 91%

Dielectric Relaxation, Ionic Conduction and Complex Impedance Studies on NaNo3 Fast Ion Conductor

Kumar¹

2013

IJMSA

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“…At temperature about 70°C the MWS relaxation peak starts appearing in PVDF whereas in PVDF/BaTiO 3 nanocomposites the MWS peak is seen at higher temperature about 90°C. In semicrystalline polymers, the crystalline regions are dispersed in amorphous matrix and MWS relaxation is observed in these materials due to the differences in the conductivity and permittivity values of the crystalline and amorphous phases [28,24]. For heterogeneous composite, an interfacial polarization is almost always present because of filler additives or even impurities that migrate towards the interface [29].…”

Section: Temperature Dependence Of Dielectric Constantmentioning

confidence: 99%

Dielectric relaxations in PVDF/BaTiO3 nanocomposites

Chanmal¹,

Jog²

2008

Express Polym. Lett.

293

164

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Abstract. The present work aims at the study of molecular relaxations in PVDF/BaTiO3 nanocomposites using broadband dielectric spectroscopy. The nanocomposites of PVDF with BaTiO3 (10-30% by wt%) are prepared using simple melt mixing method. In dielectric permittivity study, two relaxation processes are identified corresponding to the crystalline, glass transition in the PVDF/BaTiO3 nanocomposites. The peaks shift to higher frequencies as the temperature is increased. Electric modulus formalism is used to analyze the dielectric relaxations to overcome the conductivity effects at low frequencies. In M″ spectra two peaks are observed only at high temperature and low frequency whereas a single relaxation peak appears at low temperatures. The single relaxation peak appearing at low temperatures is the αc relaxation attributed to crystalline chain relaxation in PVDF and the second relaxation peak which appears only at high temperatures and at a frequency lower than αc relaxation is identified as MWS relaxation. The temperature dependence of αc relaxation and MWS relaxation follows Arrhenius type behavior.

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“…Maxwell-Wagner-Sillars (MWS) effects are observed within this frequency range (γ in Figure 5), which is an interfacial relaxation present in heterogeneous materials when subjected to an electric field [9,10,11,12]. These heterogeneous sites include amorphous/crystalline regions, impurities or chemicals remaining from processing (i.e plasticizers or catalysts) whose permittivity or conductivity values are different from those of the main phase [10].…”

Section: Poly (Ether Ether Ketone)mentioning

confidence: 99%

“…These heterogeneous sites include amorphous/crystalline regions, impurities or chemicals remaining from processing (i.e plasticizers or catalysts) whose permittivity or conductivity values are different from those of the main phase [10].…”

Section: Poly (Ether Ether Ketone)mentioning

confidence: 99%

“…This process is the β-relaxation and is associated with the initial movement of the glass-transition relaxation (α) which occurs above 143 °C [9]. With increasing radiation exposure or thermal aging, the frequencies of the sub-glasstransition relaxations (β and γ) have been observed to decrease [9,10]. These decreases are the result of increased cross-linking (observed by an increase in C-C bonding within the IR spectrum) and oxidation in the presence of oxygen.…”

Section: Poly (Ether Ether Ketone)mentioning

confidence: 99%

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