Epoxy/clay nanocomposites: Further exfoliation of newly modified clay induced by shearing force of ball milling

To induce montmorillonite (MMT) to be further exfoliated and homogeneously dispersed in epoxy matrix (diglycidyl ether of bisphenol A) curing in the presence of diaminodiphenyl sulfone and obtain improved mechanical properties, a promising new method has been developed to prepare highly reinforced epoxy/MMT nanocomposites through exerting shearing force on epoxy/MMT solution by ball milling. Modifying agents, being combined with dodecylbenzyldimethylammonium chloride and meta-xylylenediamine, were used to organically modify the clay (MMTII). Different resultant products were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, etc, and the fracture surface of the mechanically tested specimens was also observed by scanning electronic microscopy. Results show that the novel MMTII possess a reactive interaction surface with the epoxy matrix. Exfoliation of the retained sandwich structure (being intercalated) or large agglomerates (undispersed MMTII) can be promoted by external shearing force of ball milling, and homogeneously dispersed MMTII nano-sheets in epoxy matrix nanocomposites are typically observed. Mechanical properties, especially impact toughness, can be increasingly enhanced by the newly structured MMTII and ball milling. Impact strength is increased up to 48.1 kJ m^-2 from 32.1 kJ m^-2 at 3 wt% MMTII content, which is about 50 % higher than that of pristine matrix, and the flexural strength can also be enhanced by about 8 % higher.