The Effect of Freeze-Thaw Cycles on the Mechancial Properties of Proton Exchange Membranes
| Author(s) | Aten, Alex | |
| Date Accessioned | 2013-02-21T20:13:33Z | |
| Date Available | 2013-02-21T20:13:33Z | |
| Publication Date | 2011-05 | |
| Abstract | Fuel cells could potentially provide a clean source of power for automotive uses. However, their durability needs to be increased in order to become commercially viable. A key component of increasing the durability of Proton Exchange Membrane Fuel Cells (PEMFCs) is characterizing the behavior of the proton exchange membrane at the heart of the fuel cell. This research investigates how the mechanical properties of these membranes are influenced by repeated freezing and thawing in conditions approximating those inside a fuel cell. A stack consisting of Nafion® 211 membrane held between Toray Carbon paper and bipolar plates was alternatingly placed in -20°C and room temperature conditions. After 50, 75, 100 freeze-thaw cycles the membranes were removed from the simulated stack set-up and a tensile test was performed on them. Membranes were tested in conditions of 25°C, 30% relative humidity and 80°C, 90% relative humidity. After testing the membranes the properties such as Young’s modulus, proportional limit stress, break strain, and swelling strain were analyzed and compared with results from previous work on membranes that had not undergone freeze thaw cycles. The results showed little change in the mechanical properties at conditions of 25°C and 30% RH. There appeared to be some effect on break strain, however, coming to any conclusions is difficult due to a large scatter and low sample size. Results for tests at 80°C and 90% RH show a slight decrease in stiffness, but the low magnitude of the change and no discernible trend with the number of freeze thaw cycles suggest this is more likely due to experimental scatter than the freezing treatment. Swelling results similarly show little impact of freeze thaw cycling. A small decrease in swelling due to changes in temperatures is noted, but swelling with changes in humidity seemed unaffected. | en_US |
| Advisor | Michael H. Santare | |
| Program | Mechanical Engineering | |
| URL | http://udspace.udel.edu/handle/19716/12408 | |
| Language | en_US | en_US |
| Publisher | University of Delaware | |
| Title | The Effect of Freeze-Thaw Cycles on the Mechancial Properties of Proton Exchange Membranes | en_US |
| Type | Thesis | en_US |