Synthesis of Low Methanol Permeation Polymer Electrolyte Membrane from Polystyrene-Butadiene Rubber

In order to find a low cost polymer electrolyte membrane with low methanol cross-over, the development of novel polymer electrolytes have been actively carried out in recent time as alternatives to Nafion (R), which is the state-of-the art membrane. The problems associated with these alternative membranes are higher permeability to the fuel, lower proton attraction and thermal stability. This work therefore was focused on synthesizing low methanol permeable membrane with good proton conductvity and thermal stability from locally available polymer (Polystyrene-butadiene rubber). Results obtained revealed that the synthesized membrane exhibited methanol permeation in the ranges of 2.13x10-7 to 7.58x10-7mol/cm2s which was lower than that of Nafion (R) (3.15x10-6cm2/s). The proton conductivity of the synthesized membrane is in the order of 10-2S/cm. The results also show that water and solvent uptake of the synthesized membrane are moderate as compared to that of Nafion (R). These results are influenced by the degree of sulphonation and membrane thickness ranging from 0.112mm-0.420mm.