Effects of filler material on the characteristics of electrospun polyvinyl alcohol/Nafion nanofibrous membranes

Abstract

In this study, polyvinyl alcohol/Nafion nanofibrous composite membranes were produced to investigate their possible application as a polymer electrolyte membrane (PEM) in direct methanol fuel cells. Electrospinning method was used for nanofibrous membrane production, in which the mixture of polyvinyl alcohol (PVA) and Nafion solutions was directly electrospun. Produced nanofibers were subjected to physical stabilization, filler application, and sulfonating to produce composite nanofibrous membranes. PVA and Nafion polymers were used also as filler materials. The properties of resultant composite membranes were compared in terms of water swelling, weight loss in water and methanol solution, thermal stability, morphology, proton conductivity, and methanol permeability. Proton conductivity of the membranes depending on the humidity was also investigated. TGA analysis showed that the membranes had adequate thermal properties regardless of the filler material. The nanofibrous structure was shown to be preserved by scanning electron microscopy (SEM) after treatment with water and methanol solution. It was shown that PVA/Nafion nanofibers displayed proton conductivity after filling process. The use of PVA as a filler material led to higher proton conductivity at 100 RH%. It was reported that proton conductivity could only be obtained at higher relative humidity values (>80% RH). A lower methanol permeability of PVA-filled membranes was reported.