Polybenzimidazole nanofiber produced by electrospinning

Nanofibers of aromatic heterocyclic PBI (poly(2,2'(m-phenylene)-5,5' bibenzimidazole)) polymer were made by an electrospinning process. The diameter of the fibers was around 300 nanometers. A liquid jet of a polymer solution, formed when electrical force overcame surface tension, stretched and dried as the solvent evaporated. The resulting electrically charged nanofibers were attracted to and collected on a rotating cylinder covered with aluminum foil that was electrically grounded. The fibers were collected in non-woven sheets about 20 centimeters wide and 100 centimeters long, with a compressed thickness of a few tens of microns. The mass per unit area of the nonwoven sheets was 15 to 50 g/m(2). The nonwoven fabric of PBI nanofibers was treated with sulfuric acid, and then washed, dried and heated to improve its strength. Optical microscopy showed that the electrospun PBI nanofibers fibers were birefringent. Other morphological features of these fibers were observed with scanning electron microscopy, transmission electron microscopy and atomic force microscopy.