Orthogonal structure in mesophase pitch-based carbon fibres

Abstract

Some carbon fibres showed the presence of an orthogonal structure when cross-sections were viewed with light or transmission electron microscopy. This structure was formed from a re-ordering of layer planes as a result of the interaction of mesophase with a stainless steel, square-mesh filter above the spinnerette, using laboratory-scale equipment. Where the mesophase was comparatively viscous the structure persisted and was present in the undrawn and drawn fibre; with mesophase of higher fluidity the orthogonal structure was preserved only in fragmentary or distorted form, or not at all. The structure inferred from these microscopical studies differs from that of an orthogonal pattern previously reported. Fibres spun with a filter appear to have improved mechanical properties, compared to those where no filter Was used.