Radiation-grafted membranes based on polyethylene for direct methanol fuel cells

Abstract

Styrene was grafted onto ultrahigh molecular weight polyethylene powder (UHMWPE) by gamma irradiation using a 60 Co source. Compression moulded films of selected pre-irradiated styrene-grafted ultrahigh molecular weight polyethylene (UHMWPE-g-PS) were post-sulfonated to the sulfonic acid derivative (UHMWPE-g-PSSA) for use as proton exchange membranes (PEMs). The sulfonation was confirmed by Xray photoelectron spectroscopy (XPS). The melting and flow properties of UHMWPE and UHMWPE-g-PS are conducive to forming homogeneous pore-free membranes. Both the ion conductivity and methanol permeability coefficient increased with degree of grafting, but the grafted membranes showed comparable or higher ion conductivity and lower methanol permeability than Nafion ® 117 membrane. One UHMWPE-g-PS membrane was fabricated into a membrane-electrode assembly (MEA) and tested as a single cell direct methanol fuel cell (DMFC). Low membrane cost and acceptable fuel cell performance indicate that UHMWPE-g-PSSA membranes could offer an alternative approach to perfluorosulfonic acidtype membranes for DMFC.Crown

One Step Polymerization of Sulfonated Polystyrene Films in a Dielectric Barrier Discharge

“…Usually, the sulfonated polystyrene membranes are obtained by a “liquid phase‐based” method (sulfonation of polystyrene by substitution reaction) 5. It can also be prepared by grafting styrene into thin films of fluoropolymers (such as PTFE, FEP, PFA, PVDF, ETFE…) or hydrocarbon polymers (e.g., PE) by pre‐irradiation (UV6, γ‐rays,7, 8 electron beam9), followed by a sulfonation reaction (chlorosulfonation followed by hydrolysis). In some cases divinylbenzene (DVB) is added as a cross‐linking agent.…”

Radiation-grafted materials for energy conversion and energy storage applications

“…The use of polymer powder substrates for preparation of proton exchange membranes has been recently reported [96][97][98][99]. The powder substrates offer a better penetration for monomer to the active sites formed upon irradiation consequently higher and homogenous graft levels can be achieved [72,97].…”

“…The powder substrates offer a better penetration for monomer to the active sites formed upon irradiation consequently higher and homogenous graft levels can be achieved [72,97]. Ultra-high molecular weight polyethylene powders were used as substrates for radiation grafting of styrene [96,98,99]. The graft copolymer powders were converted into films by hot-press prior to the sulfonation to yield a proton-exchange membrane.…”

Properties of Polystyrene/Acrylic Acid Membranes After Sulphonation Reactions

“…They found excellent mechanical properties, high dimensional stability and ionic conductivity for a degree of sulphonation of the unity (DS=1) for a reaction time of 3 hours and evaluated at 80 ºC. On the other hand, Sherazi et al [4] crosslinked UHMWPE with styrene and prepared membranes by press molding to then sulphonate them with chlorosulphonic acid. They obtained membranes with high proton conductivity and lower permeability to methanol than Nafion.…”