Diaphragm for electrolytic cell for chlorine production

In an electrolytic cell for the production of halogen and caustic from an aqueous alkali metal halide solution containing anode and cathode compartments separated by a diaphragm, the improvement comprising:

• a diaphragm of porous tetrafluoroethylene polymer sheet material which has an amorphous content not exceeding about 5 percent and a micro-structure characterized by nodes interconnected by fibrils, said fibrils having a diameter of about 5 to about 1,000 angstroms, said nodes having lengths of about 0.5 to about 400 microns, said sheet having a porosity of about 50 to about 90 percent, a bulk density of less than about 1.0 and a bulk tensile strength of greater than about 3,000 pounds per square inch.