Multiscale reinforcement and interfacial strengthening on epoxy-based composites by silica nanoparticle-multiwalled carbon nanotube complex

The multiscale reinforcement and interfacial strengthening on epoxy-based composites by nanoscale complex composed of zero-dimensional silica nanoparticles (SiO2) and one-dimensional multiwalled carbon nanotubes (MWCNTs) was examined. The SiO2-MWCNT complex was successfully prepared by multi-step functionalization, which was characterized with FTIR, XPS and TEM. Mechanical properties of epoxy (EP) composites were significantly enhanced by SiO2-MWCNTs rather than other functionalized MWCNTs, due to synergy reinforcing effect of MWCNTs and SiO2 as well as enlarged interfacial areas by SiO2. The chemically bonded nanoscale interfacial area between glass fiber and matrix was generated and bridged by SiO2-MWCNTs, making glass fiber like a branched reinforcement, resulting in strong interfacial adhesion and effective stress transfer. Mechanical properties of SiO2-MWCNT/EP composites and GF/SiO2-MWCNT/EP composites were even higher than those predicted by Halpin-Tsai model and rule of mixtures, resulting from strengthened interfacial adhesion in the composites, high chemical reactivity of SiO2-MWCNTs and additional reinforcing effect of SiO2.