Methanol permeability and proton conductivity of direct methanol fuel cell membranes based on sulfonated poly(vinyl alcohol)–layered silicate nanocomposites

Abstract

Layered silicate nanocomposite membranes to be used as electrolyte polymeric membranes in a direct methanol fuel cell were prepared through the mixing of poly(vinyl alcohol) (PVA) with various amounts (2, 4, and 5% w/w) of sodium montmorillonite layered silicate nanoclay. The proton conductivity of the polymer was induced by the reaction of the polymer with sulfosuccinic acid. After that, a solution of the sulfonated PVA-layered silicate nanocomposite was cast into membranes. The proton conductivity and methanol permeability of the membranes were determined with a four-point probe technique and a gas chromatography technique, respectively. In addition, structures of the nanocomposite membranes were characterized with X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared techniques. The mechanical properties of the nanocomposite membranes were also determined with a universal testing machine. From the results, it was found that the water uptake, proton conductivity, and methanol permeability of the membranes initially decreased after a 2% (w/w) concentration of the layered silicate was added. Above this nanoclay loading, the water uptake of the membranes increased again. The results were examined in the light of the interaction between the clay and sulfonated polymer, and the steric effect provided the exfoliation of the nanoclay.

Where do poly(vinyl alcohol) based membranes stand in relation to Nafion® for direct methanol fuel cell applications?

“…These results might be related to the interaction between sodium montmorillonite and PVA, exfoliation of the nanoclay in the polymer composite, and changes in the degree of crystallinity of the polymer with the nanoclay content. The optimum level of layered silicate sodium montmorillonite is achieved at which the maximum C/P ratio of the nanocomposite membrane was 2% (w/w) [109].…”

Polymer-Layered Silicate Nanocomposite Membranes for Fuel Cell Application

“…22.15). This behavior is possibly due to the low affinity of unmodified MMT towards water compared to the sulfonated PVOH along with reduced number of hydrophilic groups (due to the H-bonding between the surface -OH groups of MMT and -SO 3 H groups of sulfonated PVOH) [118]. On the contrary, lower water affinity of MMT compared to PWA reduced the water uptake of the PVA-PWA-MMT composite compared to that of the PVA-PWA composite membranes [110].…”

Zirconium phosphate based proton conducting membrane for DMFC application

“…The concentration of methanol in compartment B was determined at different times using a gas chromatograph (Make: Nucon Gas Chromatograph India, Model: 5765) equipped with flame ion detector (FID). Methanol permeability (P) at 30 C and 60% RH was calculated by the below given formula reported in literature [13],…”