Relaxation of Proton Conductivity and Stress in Proton Exchange Membranes Under Strain

2006 ◽  
Vol 128 (4) ◽  
pp. 503-508 ◽  
Author(s):  
Dan Liu ◽  
Michael A. Hickner ◽  
Scott W. Case ◽  
John J. Lesko
Keyword(s):  
Stress Relaxation ◽  
Proton Conductivity ◽  
Proton Exchange Membranes ◽  
Deionized Water ◽  
Proton Exchange ◽  
Polymer Chains ◽  
Water Condition ◽  
Arylene Ether ◽  
Conduction Pathway ◽  
Sulfonated Poly

The stress relaxation and proton conductivity of Nafion 117 membrane (N117-H) and sulfonated poly(arylene ether sulfone) copolymer membrane with 35% sulfonation (BPSH35) in acid forms were investigated under uniaxial loading conditions. The results showed that when the membranes were stretched, their proton conductivities in the direction of the strain initially increased compared to the unstretched films. The absolute increases in proton conductivities were larger at higher temperatures. It was also observed that proton conductivities relaxed exponentially with time at 30°C. In addition, the stress relaxation of N117-H and BPSH35 films under both atmospheric and an immersed (in deionized water) condition was measured. The stresses were found to relax more rapidly than the proton conductivity at the same strains. An explanation for the above phenomena is developed based on speculated changes in the channel connectivity and length of proton conduction pathway in the hydrophilic channels, accompanied by the rotation, reorientation, and disentanglements of the polymer chains in the hydrophobic domains.

Highly selective sulfonated Poly (arylene ether nitrile) composite membranes containing copper phthalocyanine grafted graphene oxide for direct methanol fuel cell

2021 ◽  
pp. 095400832110394
Author(s):  
Yan Ma ◽  
Kaixu Ren ◽  
Ziqiu Zeng ◽  
Mengna Feng ◽  
Yumin Huang
Keyword(s):  
Graphene Oxide ◽  
Proton Conductivity ◽  
Direct Methanol Fuel Cells ◽  
Copper Phthalocyanine ◽  
Composite Membranes ◽  
Proton Exchange ◽  
Methanol Permeability ◽  
Arylene Ether ◽  
Direct Methanol ◽  
Sulfonated Poly

To improve the performances of sulfonated poly (arylene ether nitrile) (SPEN)–based proton exchange membranes (PEMs) in direct methanol fuel cells (DMFCs), the copper phthalocyanine grafted graphene oxide (CP-GO) was successfully prepared via in situ polymerization and subsequently incorporated into SPEN as filler to fabricate a series of SPEN/CP-GO-X (X represents for the mass ratio of CP-GO) composite membranes. The water absorption, swelling ratio, mechanical properties, proton conductivity, and methanol permeability of the membranes were systematically studied. CP-GO possesses good dispersion and compatibility with SPEN matrix, which is propitious to the formation of strong interfacial interactions with the SPEN, so as to provide more efficient transport channels for proton transfer in the composite membranes and significantly improve the proton conductivity of the membranes. Besides, the strong π–π conjugation interactions between CP-GO and SPEN matrix can make the composite membranes more compact, blocking the methanol transfer in the membranes, and significantly reducing the methanol permeability. Consequently, the SPEN/CP-GO-1 composite membrane displayed outstanding tensile strength (58 MPa at 100% RH and 25°C), excellent proton conductivity (0.178 S cm−1 at 60°C), and superior selectivity (5.552 × 105 S·cm−3·s). This study proposed a new method and strategy for the preparation of high performance PEMs.

scholarly journals Recent Progress in the Development of Aromatic Polymer-Based Proton Exchange Membranes for Fuel Cell Applications

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1061 ◽  
Author(s):  
Raja Rafidah R. S. ◽  
Rashmi W. ◽  
Khalid M. ◽  
Wong W. Y. ◽  
Priyanka J.
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Proton Conductivity ◽  
Elevated Temperatures ◽  
Proton Exchange Membranes ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Polymer Chains ◽  
Membrane Electrode ◽  
Aryl Ether

Proton exchange membranes (PEMs) play a pivotal role in fuel cells; conducting protons from the anode to the cathode within the cell’s membrane electrode assembles (MEA) separates the reactant fuels and prevents electrons from passing through. High proton conductivity is the most important characteristic of the PEM, as this contributes to the performance and efficiency of the fuel cell. However, it is also important to take into account the membrane’s durability to ensure that it canmaintain itsperformance under the actual fuel cell’s operating conditions and serve a long lifetime. The current state-of-the-art Nafion membranes are limited due to their high cost, loss of conductivity at elevated temperatures due to dehydration, and fuel crossover. Alternatives to Nafion have become a well-researched topic in recent years. Aromatic-based membranes where the polymer chains are linked together by aromatic rings, alongside varying numbers of ether, ketone, or sulfone functionalities, imide, or benzimidazoles in their structures, are one of the alternatives that show great potential as PEMs due totheir electrochemical, mechanical, and thermal strengths. Membranes based on these polymers, such as poly(aryl ether ketones) (PAEKs) and polyimides (PIs), however, lack a sufficient level of proton conductivity and durability to be practical for use in fuel cells. Therefore, membrane modifications are necessary to overcome their drawbacks. This paper reviews the challenges associated with different types of aromatic-based PEMs, plus the recent approaches that have been adopted to enhance their properties and performance.

Sulfonated poly (arylene ether sulfone)-graft-sulfonated poly (vinyl alcohol) proton exchange membranes: Improved proton selectivity

2020 ◽  
pp. 095400832096816
Author(s):  
Hailin Yu ◽  
Yinghan Wang
Keyword(s):  
Vinyl Alcohol ◽  
Substitution Reaction ◽  
Proton Exchange Membranes ◽  
Proton Exchange ◽  
Methanol Permeability ◽  
Poly Vinyl Alcohol ◽  
H Nmr ◽  
Arylene Ether ◽  
High Proton ◽  
Sulfonated Poly

Aldehyde terminated sulfonated poly (arylene ether sulfone) (SPAES-CHO) is prepared by a series of nucleophilic substitution reaction based on SPAES in this paper. Novel SPAES-graft-SPVA (SPAES-g-SPVA) membranes are fabricated by acetal reaction between SPAES-CHO and different amounts of sulfonated poly (vinyl alcohol) (SPVA). The 1H-NMR and FTIR indicate the successful preparation of SPAES-CHO and SPAES-g-SPVA membranes. With the introduction of SPVA, the SPAES-g-SPVA membranes have much lower methanol permeability than pure SPAES membrane and Nafion117 membrane. The methanol permeability coefficients of the SPAES-g-SPVA membranes decrease from 3.41 × 10−7 cm2 s−1 to 1.67 × 10−7 cm2 s−1 with the increase of SPVA content. And the proton conductivity of all the membranes is higher than 15 mS cm−1 at 25°C. Moreover, SPAES-g-SPVA membranes exhibit high proton selectivity. Especially, SPAES-g-SPVA-30% membrane has the highest proton selectivity, which is nearly five times higher than Nafion117.

scholarly journals Synthesis and characterization of a novel crosslinkable side-chain sulfonated poly(arylene ether sulfone) copolymer proton exchange membranes

RSC Advances ◽  
2020 ◽  
Vol 10 (42) ◽  
pp. 24772-24783 ◽  
Author(s):  
Shouping Wang ◽  
Fugang He ◽  
Qiang Weng ◽  
Diao Yuan ◽  
Pei Chen ◽  
...  
Keyword(s):  
Single Cell ◽  
Proton Exchange Membranes ◽  
Proton Exchange ◽  
Side Chain ◽  
Synthesis And Characterization ◽  
High Proton Conductivity ◽  
Arylene Ether ◽  
High Proton ◽  
Sulfonated Poly

A series of novel crosslinkable and crosslinked side-chain SPAES has been prepared. The S-SPAES(1/2) has high proton conductivity and acceptable single-cell performance.

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