Proton Exchange Membranes Prepared by Radiation Grafting of N-Vinyl Imidazole/4-vinyl Pyridine onto Poly (Ethylene-alt-Tetrafluoroethylene) for High-Temperature PEM Fuel Cells
Material Science and Engineering Department, Master Thesis, 2017
Assoc. Prof. Dr. Selmiye Alkan Gürsel (Thesis Advisor)
Assoc. Prof. Dr. Gözde Ince
Assist. Prof. Enver Güler
Date & Time: 8th January, 2018, 10:00 am
Place: SUNUM G111
Keywords: Proton Exchange Membranes, N-Vinyl Imidazole, 4-Vinyl Pyridine, Radiation Grafting, High-Temperature PEM Fuel Cells
The large contribution of fossil fuels emission in environment pollution as well as limited supplies reveal the significance of an alternative power plant. In this regard fuel cells are considered as one the most favorable options for different applications. However, material properties to meet the requirements of the fuel cell systems with high performance, reliable lifetime and cost-effective is still the challenging issue. Improvement of membrane as the core component of the fuel cell is one of the growing research areas. Radiation-induced grafting method has been attracted extensive attention as a simple method for scaling up. Furthermore the ability of this method in terms of utilizing different combination of base polymers and monomers results in production of membranes with desired properties for numerous applications such as high-temperature PEM fuel cells.
In this study 1-vinylimidazole (1-VIm) and 4-vinylpyridine (4VP) monomers have been utilized as the monomers to graft onto ɣ-irradiated ETFE (ethylene-co-tetrafluoroethylene) films as the base polymer. Grafting reactions were taken place at 60°C for 24 h. The radiation grafted copolymer was subsequently doped with phosphoric acid to prepare new membranes for high temperature operation. The effect of adding ferrous salt as an initiator, utilizing different solvents during grafting and changing monomer ratio were investigated. Properties of the resultant membranes were characterized via ex-situ ionic conductivity measurement at varying temperature and humidity, thermal gravimetric analysis (TGA) and mechanical test using universal test machine. The fuel cell performance tests were carried out for the most promising membranes at various relative humidities and temperatures. Additionally, up to 237 mS.cm-1 ionic conductivity at 110 °C with 60% RH, reveals their potential as a promising membrane for high-temperature PEM fuel cell applications.