Characteristics of Fuel Cell Membranes Prepared by EB Radiation Grafting onto FEP with Styrene Derivatives, Styrene and 2-Methylstyrene

Abstract

This study used simultaneous electron beam (EB) irradiation to graft styrene derivatives onto a 125μm thick poly(tetrafluoroethylene-co-hexafluoro propylene) (FEP) film, with various grafting times ranging from 0.5 to 10 h, grafting temperatures ranging from 30 to 60°C , and radiation doses ranging from 10 to 100 kGy. The degree of grafting increased with increasing the dose to a maximum after a grafting time of 5–10 h. The electron spin resonance spectra for the produced radicals showed that the radicals were trapped in the FEP film for a long time even at room temperature, allowing continuous grafting for several hours. The grafting degree in the 2-methylstyrene monomer was lower than in the styrene one, with their grafting degrees differing by a maximum of 30% at a grafting temperature of 45°C and a dose of 50 kGy. However, the sulfonation degree of 2-methylstyrene was higher than that of styrene, in which an average of 1.5 sulfonic acid groups were attached to one 2-methylstyrene, regardless of the grafting degree, whereas for styrene it ranged from 1.3 to 0.9 depending on the grafting degree. The ion conductivity values were 2.4 S/cm for 2-methylstyrene at a grafting degree of 26.7% and 2.5 S/cm for styrene at a grafting degree of 56.2% .

Radiation-grafted materials for energy conversion and energy storage applications

“…Other alternative monomers (shown in Figure 17) such as methyl acrylate [114], 2-methylstyrene [115], 4-methylstyrene [116], 4-tert-butylstyrene [116], 4-vinylbenzyl chloride [117], 2-chloroethylvinyl ether [118], vinyltoluene [119] and 1-(4-styryl)ethyltrimethoxysilane [120] were also used for the preparation of proton-exchange membranes by radiation-induced grafting. In a recent study, radiation-grafted membranes for fuel cells containing antioxidants by using styrene and linker monomers vinylbenzyl chloride or glycidylmethacrylate were also described [121].…”

Hydrogen Economy and Polymer Membranes

“…The condition is that the concentration of the electrochemically active polymer is high enough to form a protonic conduction path, i. e. it must be higher than the percolation threshold. These composite membranes can be prepared: (a) by grafting suitable monomers to a (fluorinated) polymer film with subsequent sulfonation; [16,17] (b) by blending an acid polymer with a basic one (e.g., polybenzimidazole); [18,19] and (c) by dispersing micron-sized or larger protonexchange particles in an inert matrix. These membranes with proton-exchange particles (called heterogeneous membranes) are usually prepared by blending protonexchange particles with a binder polymer and then calendering, extruding or compression molding the membrane [20,21] or by suspending the particles in a solution of an inert polymer, casting the membrane and evaporating the solvent.…”

Mechanisms and Characterization of the Pulsed Electron-Induced Grafting of Styrene onto Poly(tetrafluoroethylene-co-hexafluoropropylene) to Prepare a Polymer Electrolyte Membrane

“…Recently, there has been a great deal of interest in the optimization of radiation grafting of fluoropolymers and styrene derivatives for fuel cell membrane applications (13–15). Published reviews by Gubler, Nasef and Kabanov describe the application of radiation towards the grafting of styrene onto various fluorocarbon polymeric substrates (16–20).…”