Synergistic effect of multi-wall carbon nanotube and organophilic montmorillonite on toughening epoxy resin

Epoxy resin matrix composites with various contents of multi-wall carbon nanotubes(MWCNTs) and organophilic montmorillonite(oMMT) were prepared by  means of shearing mixing and speed mixture. X-ray diffraction analysis shows that the exfoliated microstructure is formed when the mass fraction of oMMT was 2%. The fracture tests indicate that MWCNTs and oMMT exhibit synergistic effect on improving the critical stress intensity factor of the pure epoxy. When incorporating 2 wt% oMMT and 0.1 wt% MWCNTs into the epoxy resin at the same time，the fracture toughness of the composite is 1.77，1.45 and 1.39 times  that of pure epoxy，2 wt% oMMT/epoxy and 0.1 wt% MWCNTs/epoxy composite，  respectively. The scanning electronic microscope observations show that MWCNTs are dispersed well in the matrix and a certain degree of platelet interlocks structure is achieved. The fracture surface micrographs prove that micro-cracks，cavities and fiber pull-out are responsible for improving the toughness of MWCNTs-oMMT/epoxy resin composites.