Nanostructure analysis and dielectric properties of PVA/sPTA proton exchange membrane for fuel cell applications: Positron lifetime study

Mohammed, Wael M.; Awad, Somia; Abdel-Hady, E.E.; Hamed, Mohamed; Elsharkawy, Yehya S.; El-Sharkawy, Mohamed R.

doi:10.1016/j.radphyschem.2023.110942

Cited by 12 publications

(6 citation statements)

References 64 publications

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“…Furthermore, the total conductivity of the polymer and its free volume content in the polymer matrix are directly correlated linearly. 26 This study found that, as the electric field strength increases, sulfonation causes the free volumes to decrease. There exists an inverse relationship between the free volume content and the binding energy of charge carriers in their localized states (W m ).…”

Section: Impedance Spectroscopymentioning

confidence: 84%

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Effect of the electric field on the free volume investigated from positron annihilation lifetime and dielectric properties of sulfonated PVC/PMMA

Elsharkawy,

Mohammed

2024

Polymers for Advanced Techs

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Polymer electrolyte membranes (PEMs) play a vital role in electrochemical devices, facilitating ion conduction while blocking gases and electrons. Their effectiveness is closely linked to their microstructural properties, especially the free volume, which impacts ionic conductivity, mechanical strength, and overall device performance. This study examines the behavior of PVC/PMMA/SSA blends under electric fields, using Positron Annihilation Lifetime Spectroscopy (PALS) to assess free volume and dielectric properties. The study involved preparing and characterizing membranes through x‐ray diffraction (XRD), thermogravimetric analysis (TGA), and PALS. XRD results indicated semi‐crystalline structures with changes in intensity due to temperature variations, while TGA highlighted changes in thermal stability under different electric fields. PALS measurements showed that free volume varied with temperature and electric field strength, influencing the material's dielectric and mechanical characteristics. The results revealed that higher electric fields reduced free volume while enhancing dielectric properties. The dielectric constant and loss were found to depend on frequency, which was affected by the polar SO3H groups. Impedance spectroscopy provided further insights into the electrical properties, showing increased dc conductivity with stronger electric fields. A correlation between the free volume investigated from PAL and the electrical properties was observed. This study emphasizes the significance of free volume and external electric field in optimizing PEMs for advanced energy applications.

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Section: Impedance Spectroscopymentioning

confidence: 84%

“…Low and high conductivity in lower and higher frequency zones, respectively, are caused by poorly conducting grain borders and highly conducting grains, according to Koop's model. 24 The relation between ac conductivity and frequency obeys Jonsher's power law, 25,26 as follows:…”

Section: Ac Conductivity and Conduction Mechanismmentioning

confidence: 99%

Effect of the electric field on the free volume investigated from positron annihilation lifetime and dielectric properties of sulfonated PVC/PMMA

Elsharkawy,

Mohammed

2024

Polymers for Advanced Techs

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“…It is well known that the activation energy of the electrical conductivity represents the minimum energy required for charged particles to surmount energy barriers and participate in the conduction process. From figure 4, the activation energy E a of electrical conductivity was calculated by using the Arrhenius equation [45,46]; where T is the absolute temperature, K is the Boltzmann constant, and σ o is the preexponential factor. Figure 5 represents the activation energy of the electrical conductivity as a function of the PbO 2 concentration for unheated and heated glasses.…”

Section: Resultsmentioning

confidence: 99%

Annealing effects on the structural, positron annihilation parameters, and electrical properties of Fe₂O₃- PbO₂-TeO₂ glasses

El-Desoky,

Abdel-Hady,

Mohamed

et al. 2024

Phys. Scr.

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This study focuses on the transformation of selected glasses consisting of 20Fe2O3-(5+x) PbO2-(75-x)TeO2 (where x = 0, 5, 10, 15, and 20 mol%) with varying concentrations of PbO2, into nanomaterials through annealing at a temperature close to the crystallization temperature (Tc). The physical and chemical properties of the resulting samples were investigated. The chemical structure was analyzed using Fourier Transform Infrared spectroscopy (FTIR), which revealed no significant chemical changes except for an increase in the concentration of PbO2. X-ray diffraction (XRD) was used to study the crystal structure. Improvements were seen with increasing PbO2 concentrations, and these improvements were further increased after the sample was annealed. Furthermore, positron annihilation lifetime (PAL) spectroscopy was used to study the microstructure, more precisely the size of vacancy-type defects. A correlation was established between the PAL and the properties of the samples. The size of the vacancy-type defects was confirmed by calculating the distribution of the long lifetime deduced from the PAL. In this work, the overall influence of PbO2 concentration and thermal treatment on the chemical and crystalline structures, electrical conductivity, and microstructure of the studied nanomaterials is highlighted. The results provide valuable insights into the relationship between the PAL and the properties of the samples and provide potential opportunities to tailor their properties for different applications.

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“…The oxidation stability of the composite membrane was significantly improved after thermal cross-linking treatment. Mohammed et al 53 prepared a cross-linked PVA-sPTA membrane, incorporated with sPTA to improve the thermal stability of the membrane. Proton conductivity increased with the workload, and improved thermal stability promoted proton conductivity.…”

Section: Common Crosslinking Methods Used In the Preparation Of Npfsa...mentioning

confidence: 99%

Recent advances in non-perfluorinated sulfonic acid proton exchange membranes in the energy field

Lv,

Li,

et al. 2024

J. Mater. Chem. A

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Nanostructure analysis and dielectric properties of PVA/sPTA proton exchange membrane for fuel cell applications: Positron lifetime study

Cited by 12 publications

References 64 publications

Effect of the electric field on the free volume investigated from positron annihilation lifetime and dielectric properties of sulfonated PVC/PMMA

Effect of the electric field on the free volume investigated from positron annihilation lifetime and dielectric properties of sulfonated PVC/PMMA

Annealing effects on the structural, positron annihilation parameters, and electrical properties of Fe₂O₃- PbO₂-TeO₂ glasses

Recent advances in non-perfluorinated sulfonic acid proton exchange membranes in the energy field

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Nanostructure analysis and dielectric properties of PVA/sPTA proton exchange membrane for fuel cell applications: Positron lifetime study

Cited by 12 publications

References 64 publications

Effect of the electric field on the free volume investigated from positron annihilation lifetime and dielectric properties of sulfonated PVC/PMMA

Effect of the electric field on the free volume investigated from positron annihilation lifetime and dielectric properties of sulfonated PVC/PMMA

Annealing effects on the structural, positron annihilation parameters, and electrical properties of Fe2O3- PbO2-TeO2 glasses

Recent advances in non-perfluorinated sulfonic acid proton exchange membranes in the energy field

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Annealing effects on the structural, positron annihilation parameters, and electrical properties of Fe₂O₃- PbO₂-TeO₂ glasses