Membrane Radiation Grafting

Keywords Polymer electrolyte fuel cell - Proton exchange membrane - Radiation grafting... 

Several authors have discussed the ion exchange potentials and membrane properties of grafted cellulose [135,136]. Radiation grafting of anionic and cationic monomers to impart ion exchange properties to polymer films and other structures is rather promising. Thus, grafting of acrylamide and acrylic acid onto polyethylene, polyethylene/ethylene vinyl acetate copolymer as a blend [98], and waste rubber powder [137,138], allows... 

Gubler, L., S. A. Giirsel, and G. G. Scherer, Radiation-grafted membranes for polymer electrolyte fuel cells. Journal Fuel Cells, August 2005. 

Hietala, S., Skou, E. and Sundhokn, F. 1999. Gas permeation properties of radiation-grafted and sulfonated poly-(vinylidene fluoride) membranes. Polymer 40 5567-5573. 

Scott, K., Taama, W. M. and Argyropoulos, R 2000. Performance of the direct methanol fuel cell with radiation-grafted polymer membranes. Journal of Membrane Science 171 119-130. 

Brack, H.-P, Ruegg, D., Biihrer, H., Slaski, M., Alkan, S. and Scherer, G. G. 2004. Differential scanning calorimetry and thermogravimetric analysis investigation of the thermal properties and degradation of some radiation-grafted films and membranes. Journal of Polymer Science Part B Polymer Physics 42 2612-2624. 

Nezu, S., Seko, H., Gondo, M. and Ito, N. 1996. High performance radiation-grafted membranes and electrodes for polymer electrolyte fuel cells. Department of Energy (DOE). Fuel cell seminar, Orlando. 

Patri, M., Hande, V. R., Phadnis, S. and Deb, P. C. 2004. Radiation-grafted solid polymer electrolyte membrane thermal and mechanical properties of sulfonated fluormated ethylene propylene copolymer (FEP)-graft-acrylic acid membranes. Polymers for Advanced Technologies 15 622-627. 

Biichi, F. N., Gupta, B., Haas, O. and Scherer, G. G. 1995. Study of radiation-grafted FEP-g-polystyrene membranes as polymer electrolytes in fuel cells. Electrochimica Acta 40 345-353. 

Wang, H. and Capuano, G. A. 1998. Behavior of Raipore radiation-grafted polymer membranes in Hj/Oj fuel cells. Journal of the Electrochemical Society 145 780-784. 

Rouilly, M. V., Koetz, E. R., Haas, O., Scherer, G. G. and Chapiro, A. 1993. Proton exchange membranes prepared by simultaneous radiation grafting of styrene onto Teflon-EEP films Synthesis and characterization. Journal of Membrane Science 81 89-95. 

Brack, H.-P, Buchi, E. N., Huslage, J. and Scherer, G. G. 1998. Recent progress in the development of the radiation-grafted PSl membrane. Proceedings of the 194th Electrochemical Society Meeting, Boston, 98-27, 52. 

Horsfall, J. A. and Lovell, K. V. 2001. Euel cell performance of radiation-grafted sulphonic acid membranes. Fuel Cells 1 186-191. 

The most common material used is cellophane, which is a cellulose film, which acts as a membrane and is capable of resisting zinc penetration. The cycle life of cells utilizing this material is severely limited due to the hydrolysis of the cellophane in alkaline solution. Various methods have been tried to stabilize cellulose materials, such as chemical treatment and radiation grafting to other polymers, but none have, as of now proved economically feasible. The most successful zinc migration barrier material yet developed for the nickel—zinc battery is Celgard microporous polypropylene film. It is inherently hydrophobic so it is typically treated with a wetting agent for aqueous applications. 

Although many radiation-grafted materials have been discovered, only a limited number of them have been commercially utilized. One of the first successful applications was the use of grafted films in battery separators. Other possibilities are in ion exchange resins and membranes for separation processes. The textile industry represents opportunities in improving... 

Preparation of Permselective Membranes by Radiation Grafting of Hydrophilic Monomers into Polytetrafluoroethylene Films... 

Gupta B and Anjum N. Preparation of ion-exchange membranes by hydrolysis of radiation-grafted polyethylene-g-polyacrylamide membranes. J. Appl. Polym. Sci. 2003 90 149-154. 

Furthermore, in 2001, Ballard entered an alliance with Victrex to produce two new membrane alternatives. One membrane is based on sulfonated poly(arylether) ketone (a variant of PEEK) supplied by Victrex, which may be better suited to PEMFC fabrication applications. In March 2002, U.S. Patent 6,359,019 was issued to Ballard Power for a graft-polymeric membrane in which one or more trifluorovinylaromatic monomers are radiation graft polymerized to a preformed polymeric base. The strucmres of BAM membranes have been studied by way of small-angle neutron scattering (SANS) [97]. The study of the ionomer peak position suggests the existence of relatively small ionic domains compared to Nalion, despite large water content. Phase separation in the polymer matrix is possibly crucial for the membrane s mechanical and transport properties. 

Decent performance curves in short-term operation have been reported for radiation-grafted membranes in DMFC (Figure 27.57). An advantage versus Nation has been observed by Geiger et al. and Scott et al. (for higher current densities) but so far, all-reported DMFC measurements have been performed for short operating times [115,116]. 

A publication by the Paul Scherrer Institute reports progress in preparing membrane/electrode assemblies for polymer electrolyte fuel cells based on radiation-grafted FEP PSSA membranes [95]. Hot-pressing with Nation was used to improve the interfaces. These improved MEAs showed performance data comparable to those of MEAs based on Nafion 112 (Figure 27.58) and an service-life in H2/O2 fuel cells of more than 200 h at 60°C and 500 mA cm. ... 

FIGURE 27.56 Diagram of the preparation process for radiation-grafted membranes. (Reproduced from Geiger, A.B., Rager, T., Matejek, L., Scherer, G.G., and Wokaun, A., in Proceedings of the 1st European PEFC Forum, Btichi, F.N., Scherer, G.G., and Wokaun A. (Eds.) 2001. With permission.)... 

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