Study of lamellar structures of graft-type fluorinated proton exchange membranes by small-angle X-ray scattering: preparation procedures and grafting degree dependence for fuel application

Tran, Tap Duy; Pham, Hien Minh; Nguyen, Anh-Tuan; Luong, Anh T. Q.; Luu, Tuyen Anh

doi:10.32508/stdj.v18i3.831

Cited by 2 publications

(4 citation statements)

References 6 publications

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“…Note that in our previous works, the grafting was already confirmed using Fourier transform infrared spectroscopy (FT-IR) 12,29 and X-ray photoelectron spectroscopy (XPS) 30 . Moreover, the presence of polystyrene grafts in the grafted-ETFE films and final membranes (ETFE-PEMs) was also affirmed using ultrasmall and small-angle X-ray scattering (USAXS/SAXS) 14,21,25,27,28 and positron annihilation lifetime spectroscopy (PALS) 24,27 .…”

Section: Etfe-pem Preparationmentioning

confidence: 89%

“…The membrane exhibits good proton conductivity, mechanical integrity, and thermal stability compared to Nafion at a similar water uptake (40%). Moreover, ETFE-PEM shows the unique higher-order structures of lamellar, lamellar grains, and crystallite network structures, which are quite stable under immersed conditions 9,13,[17][18][19][20][21][22] . These hierarchical microstructural features strongly relate to the mechanical integrity of the membranes under severe operation conditions (high temperature and high relative humidity) of fuel cells 14 .…”

Section: Introductionmentioning

confidence: 99%

“…These hierarchical microstructural features strongly relate to the mechanical integrity of the membranes under severe operation conditions (high temperature and high relative humidity) of fuel cells 14 . However, previous reports mainly represented the results of ETFE-PEMs having a grafting degree (GD) higher than 19% [14][15][16][17][18][20][21][22][23][24][25][26][27][28][29][30][31] . The higher the GD is, the higher the conductance, but the lower the mechanical integrity and the higher the swelling [7][8][9]11,17,25,29 .…”

Section: Introductionmentioning

confidence: 99%

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Characterization of graft-type polymer electrolyte membranes at low grafting degrees for fuel cells

2023

Sci. Tech. Dev. J.

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Introduction: Proton exchange membrane (or polymer electrolyte membrane) fuel cells (PEMFCs) are attracting enormous research activities because they are a new power source for applications in different industrial sectors, such as transportation, stationaries, and portable devices. Nafion is the available commercial material for PEMs, but it has a high production cost, leading to a strong demand for alternative membranes. Polystyrene sulfonic acid (PSSA)-grafted poly(ethylene-cotetrafluoroethylene) (ETFE) polymer electrolyte membranes (ETFE-PEMs) have been investigated extensively as alternative membranes for PEM fuel cells, but the results are mainly reported at grafting degrees (GDs) higher than 19%. Therefore, this study reports the results of thermal stability, mechanical strength, and proton conductivity for the ETFE-PEM with a low GD of 10%. Methods: ETFE-PEM was prepared by radiation-induced grafting and subsequent sulfonation. The performance characteristics of ETFE-PEM related to fuel cells are investigated using thermal gravimetric analysis (TGA), mechanical testing, and electrochemical impedance spectroscopy. Result: The ETFE-PEM shows higher or comparable mechanical strength and thermal stability to those of Nafion. In addition, ETFE-PEM can exhibit a conductance of 6.10 −4 -21.10 −4 S/cm with a relative humidity (RH) of 40-60%, even at a very low GD of 10%. Conclusion: ETFE-PEM shows better mechanical and thermal properties than Nafion and exhibits a rapid increase in conductance with RH of 40-60%, providing a potential application in PEM fuel cells for small devices such as motorcycles, mobile phones, or portable electronics.

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Section: Etfe-pem Preparationmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterization of graft-type polymer electrolyte membranes at low grafting degrees for fuel cells

2023

Sci. Tech. Dev. J.

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“…The grafted-ETFE was then sulfonated with chlorosulfonic acid in 1,2-dichloroethane at 50 • C for 6 hours. The membrane was washed again with pure water at 50 • C for 24 h to obtain ETFE-PEM 19,20 . In this study, grafted-ETFEs and ETFE-PEMs with a GD of 106% were utilized for positron annihilation lifetime spectroscopic analysis.…”

Section: Experlmental Materials and Preparationmentioning

confidence: 99%

Effects of source correction on positron annihilation lifetime spectroscopic analysis of graft-type polymer electrolyte membranes

Nguyen,

Tran,

Dinh

et al. 2023

Sci. Tech. Dev. J.

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Introduction: Recently, the free-volume hole features of poly(styrene sulfonic acid) (PSSA)-grafted poly(ethylene-co-tetrafluoroethylene) polymer electrolyte membranes (ETFE-PEMs) have been studied using positron annihilation lifetime spectroscopy (PALS) to determine the relationship between gas crossover through a PEM and a fuel cell. As one such series, this work investigates the source correction in PAL spectroscopic analysis for ETFE-PEM. Method: ETFE-PEM was prepared by radiation-induced graft polymerization and subsequent sulfonation. The free-volume hole characteristics of ETFE-PEM with a grafting degree (GD) of 106% were determined using PALS with and without source correction. Results: After source correction, the original-ETFE and ETFE-PEM strains exhibited increases in r3 (smaller radius of free-volume holes in the lamellar amorphous regions, the PSSA grafts, and the interface zones inside the lamellae) and r4 (larger radius of free-volume holes in the mobile amorphous layers and the PSSA grafts outside of the lamellae). In addition, the full width at half maximum (FWHM) of r3 is much greater than that of r4 due to the rearrangement in the mobile amorphous region and the polystyrene layers outside the lamellar structure. Conclusion: Source correction causes a significant change in the distribution curves of r3 for the original-ETFE and ETFE-PEM. Thus, source correction of positron annihilation lifetime spectroscopic analyses is an important issue for determining the o-Ps lifetime of polymers, which is near the lifetime of positrons in source materials.

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Study of lamellar structures of graft-type fluorinated proton exchange membranes by small-angle X-ray scattering: preparation procedures and grafting degree dependence for fuel application

Cited by 2 publications

References 6 publications

Characterization of graft-type polymer electrolyte membranes at low grafting degrees for fuel cells

Characterization of graft-type polymer electrolyte membranes at low grafting degrees for fuel cells

Effects of source correction on positron annihilation lifetime spectroscopic analysis of graft-type polymer electrolyte membranes

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