Investigation on the Microscopic/Macroscopic Mechanical Properties of a Thermally Annealed Nafion® Membrane

Abstract

The Nafion® electrolyte membrane, which provides a proton pathway, is an essential element in fuel cell systems. Thermal treatment without additional additives is widely used to modify the mechanical properties of the membrane, to construct reliable and durable electrolyte membranes in the fuel cell. We measured the microscopic mechanical properties of thermally annealed membranes using atomic force microscopy with the two-point method. Furthermore, the macroscopic property was investigated through tensile tests. The microscopic modulus exceeded the macroscopic modulus over all annealing temperature ranges. Additionally, the measured microscopic modulus increased rapidly near 150 °C and was saturated over that temperature, whereas the macroscopic modulus continuously increased until 250 °C. This mismatched micro/macroscopic reinforcement trend indicates that the internal reinforcement of the clusters is induced first until 150 °C. In contrast, the reinforcement among the clusters, which requires more thermal energy, probably progresses even at a temperature of 250 °C. The results showed that the annealing process is effective for the surface smoothing and leveling of the Nafion® membrane until 200 °C.

Antimicrobial coatings based on amine-terminated graphene oxide and Nafion with remarkable thermal resistance

“…This surface smoothing points to a major surface reorganization of the polymer chains that experience temperatures far above their glass transition T g . 50 These pronounced surface rearrangements induced during thermal annealing are also reected in the signicant changes in water contact angles (q) shown in Fig. 8.…”

“…This surface smoothing points to a major surface reorganization of the polymer chains that experience temperatures far above their glass transition T g . 50 …”

Structure–Performance Correlation Inspired Platinum-Assisted Anode with a Homogeneous Ionomer Layer for Proton Exchange Membrane Water Electrolysis

“…The cell voltage of the IrO x · n H 2 O catalyst at 1000, 1500, and 2000 mA/cm 2 changed from 1.841, 1.964, and 2.117 V to 1.685, 1.785, and 1.917 V, demonstrating a voltage reduction of 8.5%, 9.1%, and 9.4%, respectively. In addition, the ohmic resistance of the five catalyst layers was also recorded with the high-frequency resistance (HFR) technique [ 59 , 60 ]. The R ohm value of Pt, IrO 2 , and IrO x · n H 2 O were 80, 132, and 180 mΩ cm 2 .…”

Annealing and TMOS coating on PSF/ZTC mixed matrix membrane for enhanced CO 2 /CH 4 and H 2 /CH 4 separation

“…On the other hand, annealing improved the mechanical characteristics of polymeric membranes by encouraging stronger connections between polymer chains and a greater degree of crystallinity in the polymer matrix. Annealing the membrane at 100, 150, or 200°C enhanced its mechanical strength from 372 to 586, 734, or 743 MPa, respectively [54]. Atomic force microscopy (AFM) observations examined the external surface topographies of MMM PSF/ZTC with various treatments.…”