Method for modifying surface of carbon fiber

The invention provides a method for modifying the surface of a carbon fiber and relates to a surface modification method. The method mainly solves the problem that the technical problem that the properties of composite material are reduced as the surface energy of the carbon fiber is improved while the body strength of the carbon fiber is lost in the existing method for modifying the surface of the carbon fiber. The method provided by the invention comprises the steps of: firstly, carrying out surface pre-treatment on the carbon fiber; secondly, immersing the carbon fiber subjected to the surface pre-treatment into a subcritical water-potassium hypermanganate system to be subjected to surface oxidation treatment; and thirdly, cleaning and drying the oxidized carbon fiber. According to the method provided by the invention, the highest oxygen content of the surface of the carbon fiber can reach up to 22.70%, and the loss of the body strength of the carbon fiber is controlled to be within 6%, so that the method provided by the invention is applicable to the fields of space flight, automobile, traffic, building, chemical industry and the like.