Burns, Doane, Swecker & Mathis
Process for the production of semipermeable polybenzimidazole membranes with low temperature annealing
 A membrane cast in the form of either a hollow filament or a flat film formed of a polybenzimidazole polymer is subjected to an annealing process by contacting the membrane with an annealing medium comprised of a solvent for the polymer and water. Such an annealing step can advantageously occur at an annealing temperature below the boiling point of water, thus avoiding the necessity for removing water present in the membrane in a conventional pre-annealing treatment step. These polybenzimidazole membranes find particular utility in reverse osmosis desalination processes. The annealing step of the present invention improves the mechanical and separative properties of the membrane and is simple in comparison to conventional annealing procedures. 
Celanese Corporation
B
B01D
inventional
Donald G. J.
Wang