10 - Heat Sealing and Repair

Abstract

Commercial heat-sealing equipment is available from Vertrod and Quiver in Milan, Italy. Quivers offers a complete system for membrane repair, including equipment to check large sheets of membranes for leaks, automated patching equipment, and patches made of Nafion® attached to a Kapton® release sheet. While melt fabrication of fluorinated ionomers is typically done in the precursor form, the finished product in the hydrogen ion form has enough melt flow to permit heat sealing and repair. Impulse heating is used for heat sealing, because at the required temperatures the ionomers undergo slow thermal degradation. Ionomers in the tetra alkyl ammonium form have a much lower melting point than ionomers containing inorganic cations. The tetra butyl ammonium form is particularly easy to heat seal. For the repair of membranes with a cathode side barrier layer, it is important that the anode side of the patch is sealed against the anode side of the membrane to be repaired.