Abstract: A method for producing polymeric, e.g., polybenzimidazole (PBI) films, is provided by forming a porous membrane by coagulating a polymeric dope solution in a liquid coagulation bath containing a non-solvent alone or a mixture of a non-solvent and solvent; submerging the resulting membrane into a non-solvent bath to remove any residual solvent; placing the membrane into an acid solution, whereby the pores become filled with the acid solution; and drying the membrane to remove residual non-solvent which collapses the porous structure entrapping the acid and forming a dense film. An alternative method involves coagulating said polymer solution directly into an acid/solvent/non-solvent mixture to produce a porous membrane which imbibes the acid solution, followed by drying.

Abstract: A method for producing polybenzimidazole (PBI) fabrics for use as fuel cell or battery electrolytes by soaking a sulfonated or non-sulfonated PBI fabric in an acid solution, whereby the fibers of the fabric become swollen with the acid solution; and drying the fabric to remove residual water or methanol and concentrating the acid.

Abstract: A method for producing polybenzimidazole (PBI) paste or gel useful in a fuel cell, mixing PBI polymer with a suitable amount of an acid, which permits the polymer to dissolve and form a matrix having a gel-like or paste-like consistency at room temperature.

Abstract: An electrically conductive shaped article such as a film or fibrous material and a process for preparing the same from a polybenzimidazole shaped article is provided. The polybenzimidazole article is first contacted with cuprous ions to produce a cuprous ion-impregnated material, and subsequently is subjected to a sulfiding agent capable of sulfiding cuprous ions, and preferably washed, to produce a polybenzimidazole shaped article having covellite copper sulfide in association therewith. Also provided are electrically conductive composites and a process for preparing the same by incorporating fibrous material prepared in accordance with the process within a substantially continuous polymeric matrix.

Abstract: The present invention relates to fiber structures and methods for obtaining tuned response to high frequency electromagnetic radiation, particularly at microwave frequencies. In one embodiment, a woven fabric is prepared with ferrite filled fibers oriented perpendicular to dielectric filled fibers. The fill of the fibers is selected to reflect radiation having a known frequency and polarization. In other embodiments, tuned structures are provided by disposing sheets containing oriented ferrite and dielectric fibers parallel to one another and moving the layers relative to one another to achieve the desired impedance for incident radiation.

Abstract: The invention concerns a high temperature lithium-sulfur secondary battery, characterized in that the cathode pellet is made from titanium disulphide. An electrolyte pellet is preferably prepared from a mixture of alkali metal halides.