PTFE-Nafion複合膜的製作及性能研究

Manufacture and Performance of Nafion-PTFE Composite Membranes

沈坤昇(Kun-Sheng Shen)

指導教授 ： 林秀麗

元智大學/工程學院/化學工程與材料科學學系/碩士(2003年)

摘要

本研究主要是研發PTFE-Nafion複合膜應用於氫氧燃料電池上，並希望能取代價格昂貴的商業膜材。本研究利用SEM、EDX、TGA、氣體滲透儀、交流阻抗儀等，來研究PTFE膜浸漬於不同Trtion濃度的Nafion溶液所製作成PTFE-Nafion複合膜的表面結構、膜材成分、耐溫性及導電度。並利用動態光散射儀來觀察不同Triton濃度對Nafion在甲醇/水(4/1 wt ratio)溶液中粒徑的分布的影響。各項實驗數據顯示當Nafion溶液中
[Trtion]≧1wt%，Nafion分子可進入PTFE膜孔洞內部，複合膜導電度
σ=1.1~1.7×10-3(S/cm)，而[Trtion]<1wt%時，其σ=6.6~9.7×10-4(S/cm) 。另外動態光散射實驗數據顯示出在溶液中加入Triton會降低Nafion分子聚集，使Nafion分子在溶液中有較好的分散性，能讓Nafion分子解離成較小的粒子，容易進入PTFE孔洞膜內。在單電池效能的測試數據顯示出，複合膜的單電池功率最大的功率密度約0.6(W/cm2)與Nafion膜製成的單電池功率密度不相上下，但成本為Nafion膜1/3價錢。

關鍵字

聚四氟乙烯 ； 全氟磺酸樹脂 ； 燃料電池 ； 質子交換膜

並列摘要

The manufacture process and performance of Nafion-PTFE composite membrane for H2/O2 fuel cell applications were studied in this thesis. Porous PTFE membrane was impregnated in Nafion solutions containing various concentration of Triton to fabricate composite membrane. SEM was used to observe the morphology of composite membranes; EDX to study the penetration of Nafion molecules in PTFE membranes; TGA to study the thermal stability; AC impedance to study the conductivity; and a home made equipment to study the gas permeability of the composite membrane. All the experimental results revealed that while the Triton concentration in Nafion solutions is lower than 1wt%, the Nafion molecules were not able to penetrate inside the pores of PTFE membranes and the conductivity of composite membranes is low. While the Triton content in the Nafion solution is higher than 1wt%, the Nafion molecules can easily penetrate into the pores of PTFE membranes, the conductivity of composite membranes is high. Dynamic laser light scattering (DLS) was used to study the particles size distribution of Nafion molecules in solution. It was found that the present of Triton in Nafion solutions results in a better dispersion of Nafion molecules in solutions, and avoid aggregation of Nafion molecules. Thus Nafion molecules were able to penetrate inside the pores of PTFE membranes lead to a better performance of composite membranes.

並列關鍵字

PTFE ； Nafion ； proton exchange membranes ； fuel cell

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