Polytetrafluoroethylene membrane reinforcement

Recently, they fabricated the polytetrafluoroethylene (PTFE)-reinforced SPEEK composite membranes to improve their chemical stability and ion selectivity in VRB applications. Compared to pristine SPEEK membranes, the composite membranes exhibited the lower swelling ratio and higher mechanical stability due to the PTFE reinforcement. As expected, the SPEEK/PTFE membranes showed much higher coulombic efficiency and energy efficiency than those of SPEEK membrane. In addition, the composite membranes exhibited much better stability than pristine SPEEK under VRB operating conditions. 

The membranous copolymer as mentioned before reinforced by a plain woven cloth of polytetrafluoroethylene was reacted with vapour of phosphorous pentachloride to form a membrane having sulfonyl chloride groups on its only one side. The membrane having sulfonyl chloride groups on its only one surface was treated by 29 % aqueous ammonia solution for 30 min. at 25 C. After the ammonia treatment, the absorption bands ascribable to... 

Figure 10.3.18 illustrates the structure of the electrode/membrane system where the membrane (e.g., Nafion 900 Series) is reinforced by a nonconductive polytetrafluoroethylene (PTFE) fabric. Note that the current flux deforms around the PTFE reinforcement, leading to an increase in the voltage drop through the membrane. Therefore, the arrangement of the PTFE reinforcement must be optimized for mechanical strength and voltage drop. 

The biggest application for fiuorinated ionomers currently is as unreinforced membranes for fuel cells, or polytetrafluoroethylene (PTFE) fiber-reinforced composite membranes for electrolytic baths. The membranes can be fabricated by the extrusion method or the solution-cast method. 

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