Ion Conducting Nanocomposite Membranes Based on PVA-HA-HAP for Fuel Cell Application: II. Effect of Modifier Agent of PVA on Membrane Properties

This work explores the synthesis and properties alteration of new nanocomposite membrane system based on polyvinyl alcohol (PVA) blended with hyaluronic acid (HA) and hydroxyapatite (HAP) as nanofiller. The membranes were synthesized by solution-casting method, where PVA was initially modified with orthophosphoric acid (OPA) or sulphuric acid and then epichlorohydrin (EPI) was employed as chemical crosslinker. Physicochemical properties of composite membranes e.g. gel fraction (%), swelling degree and mechanical stability were estimated, depending on PVA modifier agent alteration. Results revealed that the PVA-modifier agent type influenced sharply on most membrane properties. For example, the swelling ability of PVA-HA-HAP composite membranes was reduced apparently with increasing H2SO4 amount as used for PVA modification, unlike it was increased with the used amount of OPA for the same purpose. The mechanical properties were improved with increasing the amount of EPI until certain extent, whereas they have deteriorated controversially with addition of high incorporated amounts of HAP or using high amounts of OPA or H2SO4 for PVA modification. Meanwhile, electrochemical properties of PVA-HA-HAP composite membranes showed a big improvement in ionic conductivity with PVA modification and HAP incorporation as well. An one-dimensional matlab model is devoloped to study the performance of DMFC for different new composite membranes. Both experimatl and modeled performance of differnet membranes in DMFC were compared and discussed in details.