Enhanced Interfacial Adhesion and Properties of Polypropylene/Carbon Fiber Composites by Fiber Surface Oxidation in Presence of a Compatibilizer

With the aim of improving the mechanical strength of polypropylene (PP) materials, carbon fibers (CFs) were incorporated into it to prepare composites with PP-graft-maleic anhydride (PP-g-MAH) as the compatibilizer. In order to improve the interfacial bonding between filler and matrix, the CFs were oxidized with concentrated nitric acid for different times. The results showed that with the increase of oxidation time, the surface roughness and specific areas of CF increased. Nitric acid oxidation can effectively introduce polar groups on the surface of CFs, leading to the increased wetting ability. The tensile and impact strength of PP/CF composites were highly improved with the increase of oxidation time. Both the increased surface areas and roughness were beneficial for mechanical interlocking. In addition, the chemical bonding between activated CF and PP-g-MAH contributed to the enhanced mechanical properties of the resulting composites. The -OH groups on CF produced by surface oxidation could react with anhydride groups, while the PP chains of PP-g-MAH diffused into the PP matrix, resulting in good adhesion or entanglement. These PP/CF composites with high performance can find wide applications as light weight structural materials. POLYM. COMPOS., 40:E654-E662, 2019. (c) 2018 Society of Plastics Engineers