Preparation of graphite fibers from polymeric fibers

The preparation of high tensile strength, high modulus of elasticity graphite fibers from polymeric fibers was investigated. Several polymeric yarns were subjected to TGA to 1000°C., the carbon yields of which indicated that polyacrylonitrile, an aromatic polyamide, and an aromatic polyimide were promising graphite precursors. Commercially available rayon‐derived carbon yarns from three sources were graphitized by a continuous process. Application of stress to the carbon yarns during graphitization was found to stretch the fibers and to induce high tensile strength and high moduli in the products. The increase in tensile strength and modulus were shown to be related to the degree of orientation along the fiber axis by x‐ray diffraction.