Surface Treatment and Sizing of Carbon Fibers

Treatments can be applied by a batch or continuous process and obviously, fiber production will favour the latter. Many methods of oxidative surface treatment have been used including gaseous, solution, electrochemical, plasma and catalytic. 

Various forms of non-oxidative surface treatments can be used, including the deposition of an active form of carbon, the deposition of pyrolytic carbon and by grafting a polymer onto the fiber surface. 

Factors which must be taken into consideration when choosing a system include the length of time that the surface treatment will take, how practical it is to operate, the cost of the treatment, whether the weight loss is significant and, if the process involves a wet system, then the incorporation of a drying stage. 

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Fitzer, E. and Weiss, R. (1987) "Effect of surface treatment and sizing of C-fibers on the mechanical properties of CFR thermosetting and thermoplastic polymers", Carbon 21, 455-467. 

More than 95% of current carbon fiber production for advanced composite appHcations is based on the thermal conversion of polyacrylonitrile (PAN) or pitch precursors to carbon or graphite fibers. Generally, the conversion of PAN or pitch precursor to carbon fiber involves similar process steps fiber formation, ie, spinning, stabilization to thermoset the fiber, carbonization—graphitization, surface treatment, and sizing. Schematic process flow diagrams are shown in Eigure 4. However, specific process details differ. 

Effect of size and surface treatment of carbon fibers on mechanical properties of magnesium matrix composites ... 

Applications. The following uses of contact angle were reported in the literature surface energy of different sizes for fibers, correlation between contact angle of fiber and interlaminar shear strength of composite, effect of surface treatment of fillers for paints, the matrix-filler adhesion parameter for PS filled with CaCO, dispersion stability of PEO-modified kaolin particles, determination of contact angle of carbon fibers and its dependence on treatment, wettability of fiber sur-... 

Lukjanova and Lovzova [1] have described how carbon fibers occur in nature. Certainly, more research on surface treatment should help to apportion a specific treatment for a given matrix. The introduction of better sizes would be expected, probably applied by electrodeposition, or electropolymerization, to provide better control during apphcation. The surface treatment of carbon fiber may be tailored for a given resin matrix and similarly, the size can be chosen to perform with a given resin matrix or production process. Hydrosize Technologies Inc. has developed a special size for vinyl esters [2]. 

The carbon fiber production process involves a series of steps including spinning of the precursor fiber, stabilization, carbonization, and post-carbonization treatments that include sizing and surface treatments. The specifics of these steps vary greatly, depending on the precursor material and the desired properties of the carbon fiber. Figure 4 shows a schematic of the carbon fiber production process. 

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