| 초록 |
Membrane-electrode-assembly (MEA), which is composed of anode- and cathode-based gas diffusion layer (GDL), and polymer electrolyte membrane, is generally prepared by a hot-pressing method. The decisive factors to prepare MEA effectively by this method are temperature, pressure, and hot pressing time. Thus, it will be meaningful to consider the relationship between these factors and physical properties of the polymer electrolyte membrane, so as to find the appropriate MEA preparation condition, concerning the stress-relaxation of the sulfonated polymers as proton exchange membrane. It was previously reported that the proton and methanol transport properties were significantly affected by annealing treatment of an amorphous glassy polymer. In the present study, sulfonated polyimide (SPI) membranes were prepared via the solution-thermal imidization of naphthalenic dianhydride and diamines such as sulfonated diamine (ODADS) and non-sulfonated diamine (ODA). The SPI membranes showed various ion exchange capacities (0.80 to 2.68 meq/g), depending upon the amount of sulfonated diamine. The change of physical properties for thermal history of the membranes was mainly studied using dynamic mechanical analysis (DMA) in relation to the described factors. The change of physical properties of membrane in fully hydrate state was also observed considering the fuel cell operation at ambient humidified condition. |
