Synthesis and characterization of heteropolyacid (H3PW12O40) embedded poly (vinyl alcohol)-g-acrylamide copolymeric membranes and their evaluation for proton exchange membrane fuel cells

Abstract

The present study reports the synthesis of poly(vinyl alcohol)-g-acrylamide (PVA-g-AAm) copolymer by grafting in presence of benzoyl peroxide initiator via free radical polymerization. The crosslinking was donein-situ bythe addition of glutaraldehyde. The membranes were prepared by solution casting and solvent evaporation technique. The different amounts of heteropolyacid i.e Phosphotungstic acid hydrate (H3PW12O40) (HPA) was incorporated into the PVA-g-AAm membranes. The membranes were sulfonated by soaking in the solvent bath. The prepared membranes were characterized by FTIR to confirm the formation of the copolymer. The surface morphology is studied using SEM. The water uptake test, contact angle measurement, and ion exchange capacity were conducted to measure the physical properties of the prepared hybrid membranes. The modified membranes showed good proton conductivity at 50 °C around 10−2 Scm−1 and lower H2 permeability as compared to standard Nafion 115 membrane. The membrane containing 10 wt. % HPA PVA-g-AAm sulfonated membranes performed better with 0.578 Scm−1 as compared to plain PVA-g-AAm sulfonated membrane which shows the conductivity 0.248 Scm−1 under fuel cell atmosphere. The obtained results suggested that the incorporation of HPA into the proton-conducting copolymers is a good candidate for elevated temperature operation of proton exchange membrane fuel cells. Application to operate fuel cells at elevated temperatures is now being investigated.