The state-of-the-art of polymer electrolyte membrane fuel cell (PEMFC) technology is based on perfluorosulfonic acid (PFSA) polymer membranes operating at a typical temperature of 80 °C. Some of the key issues and shortcomings of the PFSA-based PEMFC technology are briefly discussed. These include water management, CO poisoning, hydrogen, reformate and methanol as fuels, cooling, and heat recovery. As a means to solve these shortcomings, high-temperature polymer electrolyte membranes for operation above 100 °C are under active development. This treatise is devoted to a review of the area encompassing modified PFSA membranes, alternative sulfonated polymer and their composite membranes, and acid−base complex membranes. PFSA membranes have been modified by swelling with nonvolatile solvents and preparing composites with hydrophilic oxides and solid proton conductors. DMFC and H2/O2(air) cells based on modified PFSA membranes have been successfully operated at temperatures up to 120 °C under ambient pressure...

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Approaches and Recent Development of Polymer Electrolyte Membranes for Fuel Cells Operating above 100 °C

http://www.engr.uconn.edu/~jmfent/membrane%20review%201.pdf

Proton-conducting polymer electrolyte membranes based on hydrocarbon polymers

The field of enthalpy relaxation is reviewed. Current phenomenologies for dealing with the non-linear and non-exponential character of enthalpy relaxation are presented, and their successes and shortcomings are discussed. Qualitative experimental data and quantitative parameterizations are summarized, and some directions for future research are suggested.

Enthalpy relaxation and recovery in amorphous materials

Synthesis and characterization of sulfonated poly(ether ether ketone) for proton exchange membranes

https://faculty.kfupm.edu.sa/che/zaidismj/publications/membranes_heteropolyacids_fuelcells_memb.pdf

Proton conducting composite membranes from polyether ether ketone and heteropolyacids for fuel cell applications

Sulfonation et neutralisation controlees de PEEK, caracterisation de PEEK sulfone et effet de cette modification sur la cristallinite, les transitions thermiques et la stabilite thermique

A sulphonated poly(aryl ether ketone)

Annealing of polymers below the glass transition temperature results in a decrease in enthalpy that is recovered during heating. The enthalpy recovery is visible as an endothermic peak in a differential scanning calorimetry (DSC) scan. The position of this peak depends on the thermal treatment given and on the structure of the material itself. Because different polymers behave differently, the phenomenon can be utilized to investigate polymel-polymer miscibility of polymers with similar Tg values. Therefore, by annealing the blends at the temperature of interest and subsequent sub-T, annealing, one can monitor phase behavior resulting from the initial treatment by inspection of the enthalpy recovery. Two systems were investigated to illustrate this: an immiscible blend of poly(viny1 chloride) and poly(isopropy1 methacrylate) and a miscible blend of poly(viny1 chloride) and poly(methy1 methacrylate).

/pdf/polymer-polymer-miscibility-and-enthalpy-relaxations-15qbz7y8ky.pdf

Polymer-Polymer Miscibility and Enthalpy Relaxations

A classical thermodynamic theory is used to derive expressions for the depression of the glass transition temperature Tg of a polymer network by a diluent. The enhanced sensitivity of Tg in cross-linked systems to small amounts of diluent is explained. Predictions of the theory are in satisfactory agreement with the experimental values of a particular polymer network/diluent system.

/pdf/depression-of-glass-transition-temperatures-of-polymer-2y3cf8gt9v.pdf

Depression of Glass Transition Temperatures of Polymer Networks by Diluents

Nature of the water-epoxy interaction

Comparaison des resultats experimentaux du comportement de phase des melanges avec les predictions d'un modele d'interaction binaire a champ moyen. Presque tous les melanges etudies sont immiscibles confirmant l'axiome que des polymeres de structure analogue sont immiscibles. Interet de la methode de la relaxation d'enthalpie pour l'etude de la miscibilite de polymeres dont les Tg sont quasi identiques

Thomas S. Ellis

Papers

A sulphonated poly(aryl ether ketone)

Polymer-Polymer Miscibility and Enthalpy Relaxations

Depression of Glass Transition Temperatures of Polymer Networks by Diluents

Nature of the water-epoxy interaction

Aromatic polyamide blends: enthalpy relaxation and its correlation with phase phenomena