The electric field effect on the nanostructure, transport, mechanical, and thermal properties of polymer electrolyte membrane

In the present study, the effect of electric field on thermally treated Nafion 112 was investigated successfully. The electrically modified Nafion membranes were examined using various techniques such as Fourier transform infrared (FTIR), water uptake, wide-angle x-ray diffraction (WAXD), proton conductivity, thermogravimetric analysis (TGA), tensile test, and positron annihilation lifetime (PAL) spectroscopy. The FTIR patterns show that the chemical structure of the Nafion 112 is unchanged with the electric field. The electric field decreases the degree of crystallinity as deduced from WAXD. Furthermore, the hole volume size deduced from PAL measurement increases with increasing the electric field strengths. As a result of the electric field effect on the thermally treated Nafion 112 membrane, the electrochemical properties were enhanced. The proton conductivity increases from 1.0 × 10–3 to 2.1 × 10–3 S/m. The water uptake increases from 7.4 to 15.5% with increasing the electric field strength up to 80 MV/m and then it reaches a plateau. It was also found that the mechanical and thermal properties of thermally treated Nafion 112 were enhanced because of the electric field effect. The hole volume size was increased from 0.136 to 0.160 nm3 as a function of the electric field. The results from different techniques were correlated successfully. The results were presented and discussed accordingly on a theoretical basis and compared to literature review data.