Fluorination of carbon fibers by halogen fluorides

Carbon fibers possess high tensile strengths and are of technological importance as reinforcing agents in composite materials. Considerable effort is being expended to modify the properties of these fibers. Treatment with the halogen fluorides, C1F₃ or BrF₅, at room temperatures results in fibers having stoichiometries C_1.69-2.3FX_0.05-0.26 where X = Cl or Br. The electrical conductivities of such fibers vary considerably during such treatment and eventually are reduced by about 3-4 orders of magnitude. However, the tensile strength of the fibers decreases by only about 50%. Other properties of the fibers such as radius, contact angle, tensile strengths, and X-ray diffraction patterns as a function of fluorination are investigated. Various applications are suggested for such fibers.