Using Time–Temperature Superposition for Determining Dielectric Loss in Functionalized Polyethylenes

Misra, Mayank; Kumar, Sanat K.

doi:10.1021/acsmacrolett.6b00978

Cited by 17 publications

(17 citation statements)

References 21 publications

(31 reference statements)

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“…The generalized Kirkwood equation was used to extract the frequency‐dependent dielectric constant, (

italicϵ

(ω) =

italicϵ

1 (ω) + i

italicϵ

2 (ω)), from the total dipole moment M ( t ) . This equation is derived by Neumann and Steinhauser specifically for a polarizable cubic system with the Ewald summation method:

F [- \frac{normald normalϕ false(t false)}{normald t}] = \frac{ϵ false(normalω false) - {italicϵ}_{\infty}}{ϵ false(0 false) - {italicϵ}_{\infty}}

and

ϵ false(0 false) - ϵ false(\infty false) = \frac{⟨ M {(t)}^{2} ⟩}{3 V k_{normalB} T {italicϵ}_{0}}

where

F [f (t)] = \int \int_{0}^{\infty} f (t) e^{- 2 π i ω t} d t

is the Fourier transform,

ϕ false(t false) = false⟨ M (0) \cdot M (t) false⟩ / false⟨ M {false(t false)}^{2} false⟩

is the normalized autocorrelation function of the total dipole moment, and

italicϵ

(0) is the vacuum permittivity.…”

Section: Experimental and Simulation Methodsmentioning

confidence: 99%

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Molecular dynamics study of correlations between IR peak position and bond parameters of silica and silicate glasses: Effects of temperature and stress

et al. 2017

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In the IR spectra of the silica and silicate glasses, the shifts of the maximum intensity position of the m Si-O-Si,as band upon heating or applying mechanical stress could be attributed to changes in the distribution of bond parameters such as bond length and bond angle. Upon heating, isotropic expansion occurs and the density changes; upon applying mechanical stress, anisotropic strain is induced and a significant change in the Si-O-Si bond angle is observed. From molecular dynamics simulations of a silica glass, we show that the peak position shift correlates better with the asymmetric change in the Si-O bond length distribution, rather than the Si-O-Si bridge angle, the O-Si-O tetrahedral angle, or the density change. This new finding provides an insight into how and why the m Si-O-Si,as IR peak of soda lime silica (SLS) glass shifts upon chemical strengthening via ion exchange and thermal tempering.

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“…The generalized Kirkwood equation was used to extract the frequency‐dependent dielectric constant, (

italicϵ

(ω) =

italicϵ

1 (ω) + i

italicϵ

2 (ω)), from the total dipole moment M ( t ) . This equation is derived by Neumann and Steinhauser specifically for a polarizable cubic system with the Ewald summation method:

F [- \frac{normald normalϕ false(t false)}{normald t}] = \frac{ϵ false(normalω false) - {italicϵ}_{\infty}}{ϵ false(0 false) - {italicϵ}_{\infty}}

and

ϵ false(0 false) - ϵ false(\infty false) = \frac{⟨ M {(t)}^{2} ⟩}{3 V k_{normalB} T {italicϵ}_{0}}

where

F [f (t)] = \int \int_{0}^{\infty} f (t) e^{- 2 π i ω t} d t

is the Fourier transform,

ϕ false(t false) = false⟨ M (0) \cdot M (t) false⟩ / false⟨ M {false(t false)}^{2} false⟩

is the normalized autocorrelation function of the total dipole moment, and

italicϵ

(0) is the vacuum permittivity.…”

Section: Experimental and Simulation Methodsmentioning

confidence: 99%

“…The generalized Kirkwood equation was used to extract the frequency-dependent dielectric constant, ((x) = 1 (x) + i 2 (x)), from the total dipole moment M(t). [34][35][36][37] This equation is derived by Neumann and Steinhauser specifically for a polarizable cubic system with the Ewald summation method: 38…”

Section: Methodsmentioning

confidence: 99%

Molecular dynamics study of correlations between IR peak position and bond parameters of silica and silicate glasses: Effects of temperature and stress

et al. 2017

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“…Higher values of dielectric loss have been seen in experiments 1 and 2 to explain the aging of HDPE after the CO 2 exposure and thermal treatment. The hydroxyl group (-OH) in non-polar polymers increases the dielectric loss factor and is associated with the size and dipole orientation for small molecules [ 76 ]. The mobility of segments in the amorphous phase and within the small portions of macromolecules are affected by polymer crystallization.…”

Section: Resultsmentioning

confidence: 99%

Degradation Monitoring of HDPE Material in CO2-Saturated NaCl Environment through Electrochemical Impedance Spectroscopy Technique

2021

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Extensive damage due to saturated seawater and CO2 exposure under high temperature and pressure in high-density polyethylene (HDPE) has been studied by Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Field Emission Scanning Electron Microscope (FESEM), and Electrochemical Impedance Spectroscopy (EIS). The degradation of square-shaped HDPE samples having 1 mm thickness was investigated at 70 bars with 60, 75, and 90 °C separately for three weeks in an autoclave chamber. A clear indication of aging was observed in terms of chain scission by the formation of the methyl group (1262 cm−1), and the appearance of degradation products, including the alcohol and hydroxyl groups. The decline in glass transition temperature (Tg), melting point (Tm), and crystallinity (Xc) result from branching and formation of degradation products in the aged samples. TGA results reveal that the degradation shifts the characteristic temperatures (T5% and T10%) to lower values compared to virgin HDPE. FESEM images show clear surface cracks and rough patches after 3 weeks. The Xc value increased due to chain mobility at higher temperatures (90 °C). The impedance is relatively high 1011 ohms.cm−2 for a virgin sample, but it drops down to 109 and 106 after degradation. Impedance and dielectric loss were correlated, and the significance of dielectric loss was observed at lower frequencies. These characterizations will contribute to more efficient and detailed evaluation criteria for degradation monitoring.

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“…Thus, the MSD parameter can qualitatively predict the dielectric loss of cellulose insulation as well as provide an understanding of the experimental phenomena at a molecular level. Compared with the methods in the previous studies [26,27], the proposed method provided a more convenient and economical approach to guide the experimental modification of cellulose insulation.…”

Section: Dielectric Loss Induced By Orientational Polarizationmentioning

confidence: 99%

Static dielectric constant and dielectric loss of cellulose insulation: Molecular dynamics simulations

Hou

Yang

et al. 2021

High Voltage

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Reducing the dielectric constant and loss of cellulose insulation can make the electric field distribution uniform in oil-paper insulation systems and decrease the heat generation in dielectric materials, thus ensuring a reliable transformer operation. To guide the experimental design from the molecular level, the fluctuation method was introduced into the molecular dynamics simulation to evaluate the static permittivity of cellulose insulation, ε s. The correlation between the dynamics parameter mean square displacement (MSD) and dielectric loss induced by orientational polarization, was investigated. The simulation results and experimental values of five types of cellulose insulation were compared to verify the rationality of the proposed method. The results indicated that the simulation values of ε s for five models were agreed well with the experimental values in terms of both the magnitude and the variation trend. The simulation time and permittivity of the surrounding medium ε RF are two key parameters, which determine the accuracy of the simulation results of ε s. Considering the convergence, 15 ns was chosen as the lower limit of simulation time. The reaction field approximation was adopted to calculate the dipole-dipole interaction instead of true interaction, that is, ε RF →∞. The MSD results reproduced the experimental trend in dielectric loss, indicating that the method can qualitatively predict the dielectric loss of cellulose insulation. Hence, these methods are sufficient to guide design experiments and provide a route to understand the mechanism of the change in dielectric properties at the molecular level. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

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Using Time–Temperature Superposition for Determining Dielectric Loss in Functionalized Polyethylenes

Cited by 17 publications

References 21 publications

Molecular dynamics study of correlations between IR peak position and bond parameters of silica and silicate glasses: Effects of temperature and stress

Molecular dynamics study of correlations between IR peak position and bond parameters of silica and silicate glasses: Effects of temperature and stress

Degradation Monitoring of HDPE Material in CO2-Saturated NaCl Environment through Electrochemical Impedance Spectroscopy Technique

Static dielectric constant and dielectric loss of cellulose insulation: Molecular dynamics simulations

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