Interface enhancement of carbon fiber reinforced methylphenylsilicone resin composites modified with silanized carbon nanotubes

Highlights: • Carbon nanotubes were chemically modified by a silane coupling agent. • Dispersion of carbon nanotubes in sizing agent was greatly improved. • The interlaminar shear strength of composites increased by 46.52%. • The impact strength of composites increased by 31.12%. • The tensile strength of carbon fiber was maintained after the sizing process. We proposed an easy and effective method to prepare multiwall carbon nanotubes (CNTs) modified sizing agent suited for carbon fibers (CFs) reinforced methylphenylsilicone resin (MPSR) composites. In order to improve the dispersion of CNTs in sizing agent and interfacial adhesion between CNTs and MPSR, CNTs were covalently functionalized with 3-aminopropyltriethoxysilane (APS) and the silanized carbon nanotube (CNT-APS) was introduced into the interface by sizing process as well. The CFs with and without sizing treatment reinforced MPSR composites were prepared by a compression molding method. Scanning electron microscopy (SEM) showed a uniform distribution of CNTs on the fiber surface and the enhancement of the surface roughness. Compared with untreated CFs composites, the interlaminar shear strength (ILSS) and impact toughness of CFs after sizing treatment containing 0.1 wt.% CNTs composites increased slightly owing to the serious agglomeration of excessive CNTs. However, the sized fibers modified with 0.5 wt.% CNT-APS composites revealed a significant increase 46.52% in ILSS and 31.12% in impact properties. Moreover, the reinforcing and toughening mechanisms were also discussed. In addition, the tensile strength (TS) of sized CFs showed a slightly increase in comparison with that of untreated CFs.