Preparation Of EVOH Proton Exchange Membrane

The traditional energy is difficult to adapt to the survival and development of human needs, because the coal, oil and natural gas was reserved and severe polluted Environment. At present all countries in the world in efforts to find new sources of energy to deal with a serious energy crisis. These new energy include solar, wind, nuclear energy, hydrogen. Hydrogen fuel cell was a device of hydrogen and oxygen as fuel through electrode reaction directly convert chemical energy into electrical energy. Its advantages include energy conversion of high efficiency, low pollution to the environment, working voltage of stable and reliable, and so on. Proton exchange membrane is an important part of hydrogen fuel cells, and played a cut off hydrogen, oxygen, conduction protons, as electric insulation effect. At present the Nafion membrane is more commonly used in proton membranes, the film has good corrosive, mechanical properties and proton conduction ability. But there are difficulties preparation, the high cost, work temperature narrow range (70-90℃), easy to cause Pt electrode poisoning, methanol permeability higher shortcomings and limited its wide application. Hydrogen fuel cells used for the hydrogen fuel and oxygen gas, gas permeability can cause membrane performance is reduced, electrode corrosion, fuel waste. So the proton film must have high block performance. Because of the existence of hydroxyl on the molecular chain of Polythene-polythene alcohol copolymer (EVOH), make its crystalline enhancement, and had very good barrier to gas. EVOH to oxygen permeability coefficient was4and hydrogen permeability coefficient was450. The best conditions of preparation EVOH proton exchange membrane and modified research of S-EVOH through a solution blend were studied in this dissertation.Its chemical structure, mechanical properties, thermal properties, protons conduction ability were characterized.In the S-EVOH proton exchange membrane preparation, the sulfonated time, temperature and catalyst type products to the influence of the proton transmission rate were discussed. The reaction temperature on the influence of the conductivity of proton exchange membrane was studied, when the temperature is80℃, its conductivity was0.003S/cm. Along with the increase of reaction time, protons film of electrical conductivity also increased, and the reaction time for16h, conductivity reached maximum0.003S/cm. In the same reaction conditions, the two different kinds of catalyst to the influence of the proton conductivity were compared, the conductivity with potassium tert-butoxide as catalyst was slightly higher than potash as catalyst. In the modification study of S-EVOH, the different quality ratio of S-EVOH/EVOH to the influence of proton conductivity was discussed. As the increase of quality ratio the conductivity increased. When quality ratio was7:3and the conductivity reached maximum0.012S/cm. S-EVOH/EVOH quality ratio continued increase, its low conductivity will next will, finally tend to the proton conductivity of S-EVOH. The thermal and mechanical properties modified films were characterized.The tensile strength, heat resistance had improved to pure EVOH film...