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.