Anodic oxidation of the carbon fiber surface is a well-established process in industrial carbon fiber production to increase the surface reactivity of the carbon fibers. It creates oxygen containing functional groups, which in turn improve the wetting properties and the bonding to a polymeric sizing and/or matrix.
In industrial carbon fiber production a dynamic oxidation process is used. The carbon fiber tow runs through a bath of electrolyte, where by application of a potential between fiber anode and cathode the electrolytic oxidation process takes place. An optimization of this dynamic anodic oxidation process is an important aspect of carbon fiber production, to improve the interaction between carbon fiber surface and polymeric sizing and/or matrix. However, on industrial scale a variation of the process parameters is difficult. Often the parameter range is limited or a parameter change, e.g. the use of a different type of electrolyte, is cumbersome.
To allow a flexible variation of all oxidation parameters, anodic oxidation on laboratory scale is performed. Here both, static and dynamic oxidation processes can be realized. Static anodic oxidation, where a spatially fixed fiber bundle is oxidized, represents the simplest oxidation setup with the lowest demand of carbon fiber material. However, the applicability of such results to a dynamic process has to be investigated.
The presented work investigates the correlation between static and dynamic anodic oxidation of carbon fibers. A comprehensive parameter variation on both laboratory setups, a static and a dynamic one, is performed. Surface chemical composition and functionality of the resulting carbon fibers is analyzed by photoelectron spectroscopy and allows for direct comparison of fiber surface properties from static and dynamic anodic oxidation.