Activated carbon fibers from poly(p-phenylene benzobisoxazole)

Abstract

Poly(p-phenylene benzobisoxazole) (henceforth abbreviated as PBO) is a rigid-rod polymer that exhibits the highest tensile modulus, tensile strength, and thermal stability among commercial polymeric fibers. Detailed information on the structure and properties of this material is available in the literature. Thermal degradation of PBO has also been investigated in some detail, mainly in connection with fire performance. Moreover, the thermal decomposition mechanism of PBO has been studied by characterizing solids resulting from partial decomposition at several intermediate temperatures. However, very little knowledge is available on carbonaceous materials derived from this polymer, which are limited to date to carbon fibers. Thus, Edie and co-workers used PBO as a source for carbon fibers, emphasizing the fact that an oxidative stabilization step was not needed; the main limitation of the resulting carbon fibers was a low tensile strength. More recently, Yokoi et al. have shown that PBO-derived carbons heat-treated at temperatures above 2000°C are transformed into graphitized carbon fibers with a high degree of axial orientation. These materials have been modified by exfoliation and then tested as components for capacitors.