Proton conductivity and methanol permeability study of polymer electrolyte membranes with range of functionalized clay content for fuel cell application

Novel phosphorylated polyvinyl alcohol (PVA) and modified kaolinite (MK) composite membranes (P-PMK) were prepared using a solution casting method. Kaolinite was modified with a silane coupling agent, aminopropyl triethaoxy silane (APTES), in order to improve the organic/inorganic interfacial morphology. First, PVA/MK composite membranes were fabricated using various wt% of MK (0–20 wt%). The prepared composite membranes were then treated with phosphoric acid (H₃PO₄). The properties of P-PMK composite membranes were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), and AC impedance. It was found that proton conductivity was increased by increasing temperature as well as filler content yielding a maximum value of 0.0611 S cm⁻¹ at 10 wt% filler content and 70 °C. The methanol permeability and water uptake were also changed by increasing filler percentage. The lowest methanol permeability, 2.87 × 10⁻⁶ cm⁻² s⁻¹, was obtained at 20 wt% filler content, which is lower than that of recast Nafion® 117. The results indicate that the PEM comprised of the phosphorylated PVA/MK composite has a good performance and can be a potential candidate for future PEMFC applications.