Non‐fluorinated PVA/SSA proton exchange membrane studied by positron annihilation technique for fuel cell application

Abstract

Poly(vinyl alcohol) (PVA) with sulfosuccinic acid (SSA) membrane was prepared with different concentrations of SSA (wt.%) and thermally crosslinked successfully at 100 °C. Ion exchange capacity and proton conductivity were found to increase with increasing the SSA content in the meantime the water uptake and hydration number were declined with the rise in the degree of sulfonation. This anomalous behavior was discussed based on Nerst equation parameters which confirm the results discussion with enhancement with data of contact angle. Tensile strength results suggest the deterioration of the PVA/SSA membranes with increasing SSA content because of the chemical reaction of SSA and PVA chains. Positron annihilation results were found to enhance the electrochemical‐mechanical results of the membranes. The o‐Ps lifetime was found to increase with increasing degree of sulfonation while SO3 was working as an inhibitor agent of PS formation as o‐Ps Intensity was declined with an elevated percentage of SSA content. The o‐Ps lifetime as a function of temperature for different PVA/SSA membranes having different SSA content increased with increasing SSA content. Furthermore, the glass transition temperature of PVA/SSA membranes was found to decrease with increasing the SSA content. The results were discussed based on the free volume theory.

Probing the Free Volume in Polymers by Means of Positron Annihilation Lifetime Spectroscopy

“…Indeed, with respect to pure PVA, an improvement in thermal stability, mechanical properties, water uptake, and ion exchange capacity is found. Awad et al [ 74 ] investigated PVA/SSA membranes with different concentrations of SSA. From PALS data, they deduced an increased thermal expansion coefficient of the free volume at increasing content of SSA, both below and above the glass transition.…”

Characterization and Modeling of Free Volume and Ionic Conduction in Multiblock Copolymer Proton Exchange Membranes

“…The analysis of the size and structure of ionic channels is crucial to determining optimal preparation routes and operating conditions for maximum performance. The best technique for this task is positron annihilation lifetime spectroscopy (PALS), which has been successfully used to study the free volume of many materials with high accuracy [20][21][22][23][24][25][26].…”

Positron annihilation lifetime spectroscopic analysis of Nafion and graft‐type polymer electrolyte membranes for fuel cell application

“…[25,28] Some works have proposed only one o-Ps component existing in the Nafion membranes [17,18,29,30] and other PEMs. [15,[31][32][33] In this case, only an average value of o-Ps lifetime for different amorphous arrangements is assumed. In contrast, other works have argued that there are two o-Ps components, which are present in at least two different amorphous arrangements in PEMs.…”