A heat-resistant emulsifying sizing agent for carbon fibers

The performance of a heat-resistant sizing agent, composed of thermoplastic polyimide GCPI TM and thermosetting epoxy 618, for carbon fibers was investigated by thermal analysis, granularity analysis, acid-alkali-titration, contact angle, and interfacial shear strength tests. It was shown that the composite emulsion has an excellent stability, is acid and alkali resistant and has a small particle size with a narrow distribution. The wettability of the emulsion to the surface of the carbon fibers can be improved by using a poly(ethylene oxide) alkyl ether surfactant. The sized carbon fibers have an improved wear resistance. The interfacial shear strength of sized carbon fibers with bismaleimide resin QY8911 shows an increase of 97% compared with that of unsized fibers. In addition, the interfacial shear strength of sized carbon fibers at 350℃ is 75.62% of the value at room temperature.