Patent ID: 8901228

Claim:
A method of producing a carbon fiber composite material comprising: a step (a) of heating first carbon nanofibers produced by a vapor growth method at a temperature that is within the range of 1100 to 1600° C. and is higher than a reaction temperature employed in the vapor growth method to obtain second carbon nanofibers; a step (b) of subjecting the second carbon nanofibers to a mechanical process to reduce the number of branch points of the second carbon nanofibers to obtain third carbon nanofibers; a step (c) of heating the third carbon nanofibers at 600 to 800° C. in an oxygen-containing atmosphere to obtain oxidized fourth carbon nanofibers; and a step (d) of mixing the fourth carbon nanofibers into an elastomer, and uniformly dispersing the fourth carbon nanofibers in the elastomer by applying a shear force to obtain a carbon fiber composite material; wherein: the step (a) and the step (c) omit (i) a heating treatment ranging from 2000° C. to 3200° C. and (ii) a graphitization step.